# Kelly Controller (KDH12600) Post-Mortem



## Tesseract (Sep 27, 2008)

...continued.

The capacitor bank is composed of (10) 330uF/200V capacitors, series KXG by United-Chemicon. This a relatively good choice of capacitor, but there could probably stand to be a few more of them, though. This is because they can each sustain 1.43A of ripple at 10kHz and 105C so a bank of 10 is good for 14.3A of ripple. There is no precise value of capacitance necessary because it depends on the motor current AND the motor inductance. Generally, though, higher current motors have lower inductance and both these things demand a higher ripple current rating of the capacitor bank. To figure out how much inductance is needed to prevent exceeding the ripple current rating of the capacitor bank you rearrange the inductance equation, V=L*(dI/dt) to L=(V*dt)/dI. Worst case ripple occurs at 50% duty cycle so if the controller regulates average motor current the ripple at 50% duty cycle will be 50% of the maximum allowed motor current (e.g. - 300A,perhaps, for this controller, though that setting can be changed in software). Thus, plugging in the numbers we get L=(108V*32uS)/300A = 11.52uH. That seems to be a reasonable minimum inductance requirement to me.

Continued... (gotta go take care of a few things - will post more later).


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## Shanex-2 (Jun 7, 2008)

Great thread keep it up. What was the rated output for that controller volts, amp, ect, ect?


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## Tesseract (Sep 27, 2008)

...continued.

The label on the KDH12600 indicates it can be used on 24-120V and deliver up to 600A. The 600A rating can be met for the semi-customary 1 minute given the specs of the MOSFETs and the heat sink but I am highly skeptical this controller would survive for long at 108V, much less at 120V. It basically comes down to stray inductance (10-30nH/inch) and the switching speed of the MOSFETs. Even at a rather leisurely transition time of 500nS (0.5uS), 600A will induce somewhere between 12 and 36V per inch of wire in voltage spike. At a minimum, one should employ an RC or RCD snubber on each leg of the half bridge AND use switches rated for 2x the maximum supply voltage. 

Also note that the est. worst case dissipation from conduction losses, only, at maximum current and duty cycle will be 480W: (600A^2) * (0.016ohms/12). 

I'm pretty sure that the microcontroller used in the KDH12600 is a Freescale *MC9S08AW16MFUE* (see Kelly-5.jpg). I'm not 100% sure because an attempt was made to obscure the part number by taking a Dremel to it - especially hilarious given the pedigree of the controller. Someone more skilled at hacking/programming but who was stumped by the conformal coating might be able to use this to their advantage....

As seen in Kelly-4.jpg, the wires from the two circular connectors are not shielded in any way from the intense magnetic ("H") field produced by the controller when switching even modest amounts of current (say, 50+ amps). Such EMI *could* easily cause the microcontroller to hang, but there are ways to prevent that in-circuit.

Finally, Kelly-3.jpg shows the underside of the controller. The most interesting thing to note here is that while all of the drains are bolted to a copper buss bar, all of the sources are merely soldered to the PCB. If this PCB were clad with 2oz copper (and this one definitely uses 1oz), the trace for the sources would need to be 13.6cm wide (~5.4") to carry 600A even allowing for a 30C temp rise!?! 

Finally, there does not appear to be any isolation between the microcontroller and the MOSFETs, hence why a separate, _isolated_ power supply is needed. So, when one of the MOSFETs failed (see the first post), likely from just the sort of voltage spike described above, the full force of the battery pack took out the microcontroller. The sheer breadth of destruction something like this inevitably causes, along with the board being coated with black polyurethane means the Kelly KDH12600 is, sadly, not practically serviceable.

Finally, my rough estimate of the parts costs, not including the enclosure (as I am not as familiar with the costs of such) is $200US. This is about right given the rule of thumb for manufacturing that says you should aim for a retail price of between 3x and 5x the parts costs (to account for labor costs, administrative, profit, etc...) *Added: the price of electronic components when purchased in large enough quantities is highly negotiable - my off-the-cuff estimate is just that, off-the-cuff.)


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## EVMAN (Jul 26, 2007)

WOW!! excellent narrative! I think U have now revealed to all the quality of Kelly controllers. There have been several threads indicating interest in purchasing this brand of controller because it was "more reasonably priced". Unfortunately, or fortunately, the old saying holds true: U get what U pay for.
I might add: ALA U know what U are paying for. U just can't beat a good track record and good customer service


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## CPLTECH (Sep 14, 2007)

I read with interest your comments (& others, too) about controllers that “die the death”. Yes, my Curtis 1231 / ADC 9” combo also had a sudden demise.

If I may add some observations from myself & others, I sense that a major part of the problem arises from the motor impedance (which you noted) & length of motor cable. Thus motor & controller need to be physically close together to keep cable as short as possible. Also, different brands & sizes of motors must be specked for COMPATIBILITY & this is not to be overlooked whatsoever (IMHO). An appropriate diode must be placed across the MOSFET/IGBT to safely stop any voltage that develops from arcing or motor impedance. Hence the need to oversize the volt & amp ratings of the various components to accommodate a multitude of possible real-world scenarios. Hence the big OEMs learned(?) early on from their warranty returns & made numerous revisions while the new guys on the block have yet to graduate from the “School of Hard Knocks”.

To illustrate the damage arcing does upstream of the actual short, here is an experience of mine:
Our company had just purchased 10 vacuum coating machines with state-of-the-art 0-10KV power supplies. We ran them at 6-7KV, yet one by one they were failing. The OEM repaired them at no charge for the first year, after that I replaced a failed $10, 15KV “door knob” capacitor. The OEM determined that the chemical we were vaporizing was causing abnormal arcing within the chamber, so reduce the voltage AND shorten the 17’ length of the Hi Voltage wire. The wire was shortened but voltage was not altered as it would affect cycle times. That mod helped but did not eliminate repeat failures.
Also we had at least 10 electric forklifts in use at the plant, but not once in 11 yrs did I hear of controller failure. Is it due to use of 48V or less? As for EV’s with 120+ volts, I believe it’s a different story & I am led to believe it is due to this induced voltage spike that prematurely kills IGBTs/MOSFETs if not sufficiently quenched. Even when relay coils are turned on & off, engineers know to add a clamping device to limit the resultant inductive spike (coils release voltage when de-energized. Ex: automotive spark-plug coil). 

May we continue to learn from each other…

94 S10 120V


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## david85 (Nov 12, 2007)

subscribing.....

And welcome to the forum, Tesseract


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## Guest (Oct 20, 2008)

Have you relayed any information to Kelly Controller of what you have found and what can be done to make a better product? If you have not then I suggest you do so they can make the changes. It is in their best interest to have a viable product and a wide open market. If you don't then I guess you will help kelly die an early death. It could be a great controller if helped. Not all of us can help and my controller is still alive. Mine is not a high power controller but it is 72 volts and 600 amps. It is also a SepEx controller. So far so good. It got a tad hot but still works. I need a good heat sink. 

Pete : )


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## Tesseract (Sep 27, 2008)

*First off, thanks for the comments. Secondly, my intent here was not so much to bash Kelly (I tried to point out the good and the bad) but rather to use their controller to illustrate the sorts of things one needs to pay attention to if you want to "roll your own".*

gottdi: I suppose it bears repeating that I am being paid to design a competing product to Kelly's, so I have no economic interest in helping Kelly out here...  That said my opinion on this in general is that, Kelly, like any other company trying to make a name for itself, ought to be pro-actively solving problems with their products, not relying on paying customers to do their beta-testing. Just my $0.02.

david85: thanks for the welcome. While I also have an economic interest in _not_ sharing too much of what I'm working on, I will share some of it.


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## Tesseract (Sep 27, 2008)

CPLTECH said:


> ...
> If I may add some observations from myself & others, I sense that a major part of the problem arises from the motor impedance (which you noted) & length of motor cable. Thus motor & controller need to be physically close together to keep cable as short as possible. Also, different brands & sizes of motors must be specked for COMPATIBILITY & this is not to be overlooked whatsoever (IMHO)....


There are a lot of trade-offs involved here but while it is overall best to keep the motor and controller as close to each other as possible, the two can be safely separated _as long as there is tight magnetic coupling between the current-carrying wires!_ That is to say, keeping the wires parallel (and preferably twisted together) from controller to motor will allow you to safely extend the distance between the two devices.

Furthermore, a higher inductance motor/wiring system will result in higher voltage spikes during switch (ie- MOSFET or IGBT) turn-off but it also will slow the rate of rise of current if, for example, the motor was locked-up or otherwise severely overloaded. This gives the controller more time to shut down drive to the switches before the current flowing through them results in failure. BTW - you typically have 10uS to turn off an IGBT in the event of a short-circuit before it is destroyed. Most of the microcontrollers used in motor controllers take 20uS or more just to execute the instructions pursuant to a fault interrupt which is why protecting against short-circuits needs to be done "in hardware" right at the switches (e.g. - desat detection). Let the microcontroller monitor and control the *average" current flowing through the switches (i.e. - throttle response).

At any rate, all of this actually reinforces your argument that motor and controller need to be matched. Unfortunately, few motor manufacturers bother to specify the inductance of their motors while few (any?) controller manufacturers specify what range of inductance their controllers can accommodate. An analagous situation would be if a gasoline engine didn't tell you what octane gasoline it needed _and gas stations didn't tell you what octane ratings they sold!_ Crazy, isn't it?

There are many other considerations but they probably belong in a separate thread.


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## Qer (May 7, 2008)

Tesseract said:


> First off, thanks for the comments. Secondly, my intent here was not so much to bash Kelly (I tried to point out the good and the bad) but rather to use their controller to illustrate the sorts of things one needs to pay attention to if you want to "roll your own".


Indeed you have pointed out several important things to consider and since I've at least been toying with the idea (Kelly seems too cheap, Zilla is out of business so it's either trying to make one myself or get a squealing Curtis), at least for EV number 2 (if number 1 ever rolls out), it's good to not run into the obvious pit falls. That Kelly doesn't even have a snubber diode in their controllers is just bizarre, I thought that was common knowledge that anything silicon based driving anything with an inductance MUST handle the kick back one way or another.



Tesseract said:


> There are a lot of trade-offs involved here but while it is overall best to keep the motor and controller as close to each other as possible, the two can be safely separated _as long as there is tight magnetic coupling between the current-carrying wires!_ That is to say, keeping the wires parallel (and preferably twisted together) from controller to motor will allow you to safely extend the distance between the two devices.


You're full of wisdom! That's a great advice, it sounds so simple when you point it out, yet I haven't even reflected over it. I've planned to run the wires in parallel from the pack to the controller (to try to avoid the car stereo picking up the noise), yet I've not even considered the motor wiring. But then, I haven't even started building... 



Tesseract said:


> Most of the microcontrollers used in motor controllers take 20uS or more just to execute the instructions pursuant to a fault interrupt which is why protecting against short-circuits needs to be done "in hardware" right at the switches (e.g. - desat detection). Let the microcontroller monitor and control the *average" current flowing through the switches (i.e. - throttle response).


Using a comparator triggering an interrupt in an AVR micro controller running at maximum speed (16 or 20 MHz depending on version) should be able to react within 1 us. Add to that slew rate etc, but it should be possible to handle it in software well within the 10 us-limit as long as you don't try to use the AD for measurement. Not in any way saying that you're wrong that the controllers usually don't do it fast enough, just pondering the fact and considering the options. It SHOULD be doable! I'll let you know as soon as the smoke clears again... 

Great postings! It sure points out several pit falls no matter if you try to build your own controller or are in the process to mate controller or motor.


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## mattW (Sep 14, 2007)

Do you think the same inductance issue is a problem at lower voltages (i.e. will this issue scale down or is it a purely post 96V phenomenon). I have a 72V 400A controller which I am aiming to use at 76.8V and ~300 amps. Other than keeping the cables short what can I do to minimise the risk of such failures?


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## Qer (May 7, 2008)

mattW said:


> Do you think the same inductance issue is a problem at lower voltages (i.e. will this issue scale down or is it a purely post 96V phenomenon). I have a 72V 400A controller which I am aiming to use at 76.8V and ~300 amps. Other than keeping the cables short what can I do to minimise the risk of such failures?


I bet Tesseract can give loads of good recommendations on this, but one thing I definitely would do is to check if the controller does snub the kick back or not. If it lacks the diode, add one externally! It will definitely make the system more robust and decrease the risk that your controller burns up.

Before this thread I'd expect all controllers to do that (as I've said before I thought that was common sense), but apparently that's not always the case. If the kick back isn't loaded down, theoretically it will reach infinite voltage. In reality there will of course be a limit, something's gonna ground the spike sooner or later, the question is only what, at what voltage and if it'll damage something in the process...


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## ngrimm (Oct 19, 2007)

Thank you for such good info. What specs would you look for in a good snubber diode on a 120v 400a controller. I will soon be testing my homemade 400a mosfet controller on my motorcycle at 72v and had completely forgotten a snubber. Thanks again for your recommendations.


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## Qer (May 7, 2008)

ngrimm said:


> Thank you for such good info. What specs would you look for in a good snubber diode on a 120v 400a controller. I will soon be testing my homemade 400a mosfet controller on my motorcycle at 72v and had completely forgotten a snubber. Thanks again for your recommendations.


Oups! That could've gone sour. 

Well, reverse voltage obviously will have to be more than the intended drive voltage, but on the other hand diodes that can handle 200-300 Volt isn't really expensive so I'd go for overkill. a quick search on Farnell gave me for example a Fairchild FFH30US30DN, a dual diode that can handle 2*30 (70 repetetive peak) Ampere and a maximum of 300 Volt reverse voltage.

I'd say that 5-10 of those (they only cost a few bucks each so why not go for overkill?) would probably handle it without problems, but I'm in no way an expert at switching electronics so please verify this before going all kamikaze on my words only...


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## Tesseract (Sep 27, 2008)

Qer said:


> ... That Kelly doesn't even have a snubber diode in their controllers is just bizarre, I thought that was common knowledge that anything silicon based driving anything with an inductance MUST handle the kick back one way or another.


I'm not sure 100% what you are referring to, but I suspect you are actually referring to the freewheeling diode that goes across the motor in 1-quadrant (no regen) controllers... No such controller would survive one switching cycle if this diode wasn't present - it conducts the motor current during the switch off time, allowing it to decay smoothly. A "snubbing" diode is used, along with a resistor and a capacitor, across the switch to form what is called an RCD snubber (also referred to as a dV/dt snubber because it slows the rate of voltage rise). This is the sort of snubber I was referring to. A mismatch in transition times between the switch and the diode, along with the stray inductance of the wiring in between them, is what leads to voltage spikes that kill one or both. For example: a rule of thumb is to assign 20nH per inch of wire (this can vary quite a bit, obviously). There's about 7" of total distance between one end of a MOSFET bank inside the KDH12600 and the other, so approximately 140nH (0.14uH) which seems neglible, really, but if you switch 600A across that 140nH in 200nS you'll produce a voltage spike of 420V. The spike has to go somewhere, usually by avalanching the opposing bank MOSFETs (after all, they will be forced into conduction if more than 150V is applied to them.) A lot of MOSFETs are designed to handle this - the FDP2532 is avalanche rated, in fact - but it is still harmful to the device and considered really sloppy by most engineers.

In switching power supplies the snubber design is arguably the single most critical aspect; throwing around even more current, as in a motor controller, only makes it more so.




Qer said:


> Using a comparator triggering an interrupt in an AVR micro controller running at maximum speed (16 or 20 MHz depending on version) should be able to react within 1 us. Add to that slew rate etc, but it should be possible to handle it in software well within the 10 us-limit as long as you don't try to use the AD for measurement. Not in any way saying that you're wrong that the controllers usually don't do it fast enough, just pondering the fact and considering the options. It SHOULD be doable! I'll let you know as soon as the smoke clears again...


Yeah, I imagine there are a bunch of ways to optimize the code which may make this do-able. Programming those little buggers is definitely not my strong suit - I have a stack of books on them but haven't managed to get through a single one... FWIW, I am looking at the ATTiny461 for my controller design as it has the fast hardware PWM built in. Not sure if I will be able to cram all of the code needed for a 2-quadrant motor controller (forward motoring and regeneration) into the 4k of memory... maybe if I leave out all of the comments...


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## ngrimm (Oct 19, 2007)

Forgive my ignorance of terms but is a snubber the same as the freewheel diode? I have twelve MBRF40250TG Schottky freewheel diodes that are rated at 40a 250v that are wired in parallel with the motor. They are mounted to the heat sink.


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## Tesseract (Sep 27, 2008)

ngrimm said:


> Forgive my ignorance of terms but is a snubber the same as the freewheel diode? I have twelve MBRF40250TG Schottky freewheel diodes that are rated at 40a 250v that are wired in parallel with the motor. They are mounted to the heat sink.



No. See above post and refer to the attached image. Components R, C and D comprise the _snubber_. If the _freewheel diode_ is replaced with a switch then you have a 2 quadrant drive (i.e. - motoring and regeneration in one direction only).


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## TheSGC (Nov 15, 2007)

Out of curiosity, would a Kelly REGEN controller be more robust since it deals with the back emf and reverse motor input?

I have a Kelly KDH09401 with regen on my series wound motor. The REGEN is disabled since I am not using a PM motor, but so far I have not have a problem. I have only run it on 60 volts tho because I don't have the front rack built for the rest of my 96 volt system.

Maybe it helps that my motor is an egg-beater (6.7 inch ADC K99-4007) and probably has a small amount of inductance compared to a 9 inch motor. Man do I need and oscilloscope......


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## Tesseract (Sep 27, 2008)

TheSGC - no, the amount of motor inductance is only relevant to how much reservoir capacitance you need (lower inductance = more capacitance) and how fast your current-limiting circuit needs to respond (lower inductance = faster response needed).

It is the inductance _in series with the collector-emitter or drain-source connections that is the problem. _Literally, the stray inductance of the circuit board or interconnect wires/buss bars inside the controller. The reservoir capacitance serves to buffer the controller from the stray inductance of the Battery (+) and (-) cables; an RC or RCD snubber is needed across the switches collector-emitter (drain-source) terminals to deal with the strays _after_ the reservoir capacitors.

Once again, the length of the cables from controller to motor is not terribly critical as the inductance of the motor will undoubtedly greatly exceed the inductance of the cables (especially if the cables are in parallel and twisted together - understandably a tough task for double-ought (00) cables). The main reason you want to keep them as short as possible is because they can be incredible H-field (magnetic) antennas spewing EMC all over the place causing other devices - like the microprocessor inside the controller itself - to go haywire.

Oh, and yeah, unless you are extremely lucky in life, you'll definitely need an oscilloscope to build a controller with half a chance of working reliably. I'm collecting my thoughts on such right now for posting in a separate thread that I'll title, "So you want to build a motor controller, huh?" In it I'll address some of the things to consider before blowing up thousands of dollars worth of parts, getting one or both eyes poked out, etc...


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## Qer (May 7, 2008)

Tesseract said:


> I'm not sure 100% what you are referring to, but I suspect you are actually referring to the freewheeling diode that goes across the motor in 1-quadrant (no regen) controllers... No such controller would survive one switching cycle if this diode wasn't present - it conducts the motor current during the switch off time, allowing it to decay smoothly. A "snubbing" diode is used, along with a resistor and a capacitor, across the switch to form what is called an RCD snubber (also referred to as a dV/dt snubber because it slows the rate of voltage rise). This is the sort of snubber I was referring to. A mismatch in transition times between the switch and the diode, along with the stray inductance of the wiring in between them, is what leads to voltage spikes that kill one or both. For example: a rule of thumb is to assign 20nH per inch of wire (this can vary quite a bit, obviously). There's about 7" of total distance between one end of a MOSFET bank inside the KDH12600 and the other, so approximately 140nH (0.14uH) which seems neglible, really, but if you switch 600A across that 140nH in 200nS you'll produce a voltage spike of 420V. The spike has to go somewhere, usually by avalanching the opposing bank MOSFETs (after all, they will be forced into conduction if more than 150V is applied to them.) A lot of MOSFETs are designed to handle this - the FDP2532 is avalanche rated, in fact - but it is still harmful to the device and considered really sloppy by most engineers.
> 
> In switching power supplies the snubber design is arguably the single most critical aspect; throwing around even more current, as in a motor controller, only makes it more so.


Oh. Ok, I blame ignorance combined with the fact that English isn't my first language. I understood totally wrong when you reported that the Kelly lacked snubber. I thought you meant that the freewheeling diode were missing and wondered how any Kelly could even survive! Carry on, nothing to see, nothing to see... 



Tesseract said:


> Yeah, I imagine there are a bunch of ways to optimize the code which may make this do-able. Programming those little buggers is definitely not my strong suit - I have a stack of books on them but haven't managed to get through a single one... FWIW, I am looking at the ATTiny461 for my controller design as it has the fast hardware PWM built in. Not sure if I will be able to cram all of the code needed for a 2-quadrant motor controller (forward motoring and regeneration) into the 4k of memory... maybe if I leave out all of the comments...


No problem, really. If you're careful and write your code efficient you can cram A LOT into 4k flash even if you use C or C++ rather than assembler. One project here at work measures decay times on an AVR that runs at 8 MHz and by hand optimizing the while-statement I managed to reach a sample frequency of 2 MHz without using assembler. I did, however, disassemble the code to verify that it was optimized and, frankly, I can't figure out a way to do it faster than the compiler did so I'm satisfied. 

An AVR takes at least 4 clock cycles to react on an interrupt and if you're careful so nothing turns off the interrupts more than absolutely necessary I believe it should be possible to keep it at least under 10 worst case. That would mean that from the CPU detecting the pin change it should be able to pull the plug on the PWM in maybe as little as 0.5 us. Add to that the response time for the electronics and it should be possible to keep it to just a few us.

Tell you what, if you design the hardware I'll gladly write the software. Wanna get rich?


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## Tesseract (Sep 27, 2008)

Qer said:


> ...
> An AVR takes at least 4 clock cycles to react on an interrupt and if you're careful so nothing turns off the interrupts more than absolutely necessary I believe it should be possible to keep it at least under 10 worst case. That would mean that from the CPU detecting the pin change it should be able to pull the plug on the PWM in maybe as little as 0.5 us. Add to that the response time for the electronics and it should be possible to keep it to just a few us....


Huh... you just about have me convinced you *can* do it in software, and not even with a 20MHz clock for the AVR... I still think I'd sleep better at night knowing there was local desaturation detection in the event of an extreme overload (think, wrench dropped across the motor terminals). It's not as daunting a task as it sounds as that function is built in to IGBT gate driver optocouplers like Avago's ACPL-332J.


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## Qer (May 7, 2008)

Tesseract said:


> Huh... you just about have me convinced you *can* do it in software, and not even with a 20MHz clock for the AVR... I still think I'd sleep better at night knowing there was local desaturation detection in the event of an extreme overload (think, wrench dropped across the motor terminals). It's not as daunting a task as it sounds as that function is built in to IGBT gate driver optocouplers like Avago's ACPL-332J.


Frankly, I think the same. 

I'd like to have an over current circuit that first pulls the interrupt on the controller to give it a chance for a graceful back off (for example if you floor it from a stand still in 5:th gear at an uphill sloap with a 2 ton trailer behind you), but if the current continues to raise even higher it pulls reset on the whole circuit, trips the contactor and thus cuts off the whole circuit from the battery pack. That would both give a physical protection of the transistors in case the software goes bonkers (or the driver is a journalist...) and protect the passengers from a dangerous situation in case the controller breaks down fatally and it all turns into a runaway situation.

But yes, if there's no software errors and the current doesn't spike away like a crazy antilope I think the software can be written in a way that the situation can be handled gracefully.


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## Tesseract (Sep 27, 2008)

QER - The overcurrent condition you mentioned - flooring it when the vehicle is grossly overloaded, on an incline, etc. - is what i would call a "routine emergency", if that makes any sense. In such a case the microcontroller should have plenty of time to respond because the motor inductance will limit how fast the current can rise. For example, if the motor inductance is 100uH and the pack voltage is 150V then the current will increase at the rate of 150V/10uH = 1.5A/uS. It will take a rather leisurely 400uS for the current to reach the 600A "continuous" rating of the controller - plenty of time for even the slowest microcontroller to respond. I bet even a BASIC Stamp would be fast enough to react to an overcurrent condition in this situation 

Drop a wrench across the motor terminals, though, and there is only the wiring inductance to oppose the rise in current. That may amount to only 0.1uH to 1uH. With a rather generous 1uH of inductance (0.02-0.2uH is more likely) the current will rise 100x faster than in the above example, giving you a mere 4uS before hitting the 600A limit. Thus, it is for *that* situation I avoid relying on software...

PM sent, btw.


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## ngrimm (Oct 19, 2007)

So do you think Curtis offers reliability over that Kelly controllers and if so why? For instance unless I am overlooking something Curtis doesn't appear to employ any snubber components either. http://cafeelectric.com/curtis/curtisschematic.pdf


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## Qer (May 7, 2008)

Tesseract said:


> QER - The overcurrent condition you mentioned - flooring it when the vehicle is grossly overloaded, on an incline, etc. - is what i would call a "routine emergency", if that makes any sense. In such a case the microcontroller should have plenty of time to respond because the motor inductance will limit how fast the current can rise. For example, if the motor inductance is 100uH and the pack voltage is 150V then the current will increase at the rate of 150V/10uH = 1.5A/uS. It will take a rather leisurely 400uS for the current to reach the 600A "continuous" rating of the controller - plenty of time for even the slowest microcontroller to respond. I bet even a BASIC Stamp would be fast enough to react to an overcurrent condition in this situation


That's much slower than I anticipated, it's actually so slow that you could even see it in time with the built in ADC if you measure the current over a shunt. Although, that would depend on how much resolution and S/N-ratio you want, but with 8 bit, quick-n-dirty, noise all over the place a conversion can be done in as little as 13 us on an AVR ATmega48.

Which makes me wonder even more how that journalist (another thread) could burn the controller by flooring the poor car in 3:rd gear. Seems like a pretty rotten design to me, or at least not really properly tested.



Tesseract said:


> Drop a wrench across the motor terminals, though, and there is only the wiring inductance to oppose the rise in current. That may amount to only 0.1uH to 1uH. With a rather generous 1uH of inductance (0.2-0.2uH is more likely) the current will rise 100x faster than in the above example, giving you a mere 4uS before hitting the 600A limit. Thus, it is for *that* situation I avoid relying on software...


And with 0.1 uH and 0.4 us the margins are a bit too little for my good nights sleep as well... 



Tesseract said:


> PM sent, btw.


Yup. Got it yesterday but time here was so late I decided to answer it tomorrow (today, that is). However, I need some coffee first. Stay tuned...


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## Tesseract (Sep 27, 2008)

ngrimm said:


> So do you think Curtis offers reliability over that Kelly controllers and if so why? For instance unless I am overlooking something Curtis doesn't appear to employ any snubber components either. http://cafeelectric.com/curtis/curtisschematic.pdf



I have not actually seen the inside of a Curtis controller and since proper layout is at least half of what makes a given high-power circuit reliable it would be unfair of me to comment one way or the other in general. That said, the Curtis does appear to make many of the same mistakes as the Kelly - sensing current via the voltage drop across the FETs; no snubbing whatsoever; relying on the FETs going into avalanche to handle the spikes during switch turn-off; probably a few other things, too.

I had mentioned previously that relying on avalanche to handle spikes is sloppy. There are two main reasons why: it is brutal to the semiconductor undergoing it and it happens so abruptly it often creates ringing and spikes itself. Any semiconductor junction can undergo avalanche, btw - it's what happens whenever you exceed its reverse voltage rating! Usually this results in the magic smoke escaping, but the avalanche mechanism can be fine-tuned by introducing specific types and amounts of impurities into the silicon die. Which is how we get zener diodes, Transorbs and avalanche-rated FETs. 

At any rate, the key thing to remember about avalanche is it causes a tremendous amount of heating in the semiconductor, and heat is the enemy of all semiconductors. This is *probably* why the Curtis controllers switch to a lower frequency at high current levels: to increase the time between avalanching so that the heat produced from it will spread out across the die rather than melt a hole through it.


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## TheSGC (Nov 15, 2007)

I find it interesting that you say not using a RCD snubber is a mistake, when every electrical engineer I have talked to about dc controller design said using a RCD snubber was a mistake because it scewed with the square wave. I originally had a RCD snubber in my controller design, but was told to dump it by my professor (the one who runs the EV department) and just use a massive freewheel diode. 

I am going to finish protoboarding my PIC controller and use an oscillopscope at school and check out the waves and make sure my gate drive resistor is correct. And I might just my Kelly along and see what that one is doing for it's waves...


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## Tesseract (Sep 27, 2008)

TheSGC said:


> I find it interesting that you say not using a RCD snubber is a mistake, when every electrical engineer I have talked to about dc controller design said using a RCD snubber was a mistake because it scewed with the square wave. I originally had a RCD snubber in my controller design, but was told to dump it by my professor (the one who runs the EV department) and just use a massive freewheel diode.


 If the switch turn off time is matched perfectly with the FWD turn-on time (i.e. reverse recovery time) then life is peachy: current smoothly transfers from flowing through the switch to flowing through the FWD. What happens. though, if those times are not perfectly matched? Say the switch turns off in 100nS while the FWD takes 200nS to recover from reverse bias? This is not an implausible example, rather, it is practically guaranteed to happen at some point. How does a massive FWD stop the switch from seeing a huge voltage spike? Conversely, if an avalanche diode is internally fitted across the switch, how do these folks propose dealing with the ringing produced when it turns on - to quench the overvoltage spike - in 3-5nS? What I'm basically getting at is that, practically speaking, it's difficult - not impossible - to avoid the use of a snubber. That plenty of DC motor controllers don't have them is proof they aren't necessary; that said controllers still blow up on occasion suggests they ought to have been considered, eh?

That said, as the duty cycle of the switch approaches 100% the effectiveness of the RCD snubber approaches zero - there simply is no time for the capacitor to discharge. However, as the off time gets shorter the voltage can't build up as much, either.

Finally, most modern industrial VFDs (which use large IGBT modules as a rule, mind you) _do not_ use RCD snubbers for each IGBT, rather, only a 1-3uF polypropylene capacitor is placed directly across each half-bridge module (for the chopper configuration, the cap would go from FWD cathode to switch emitter or source). The waveforms on these machines I've seen are usually textbook perfect, so go figure.

Certainly there's more than one way to skin this particular cat,


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## TheSGC (Nov 15, 2007)

Ok, got it. My design does have a driver and when I get the time, I am going to get the gate resistor right for the proper timing. (I will get some help my uncle and his oscilloscope to get the gate drive squared down)

And a question on the cable lengths from controller to motor- I have three foot lengths at the moment, which doesn't seem to long but I will try to rearrange things to get it down another 1-1.5 feet smaller- Is three feet too long?


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## fugdabug (Jul 14, 2008)

Tesseract said:


> ...continued.
> 
> The label on the KDH12600 indicates it can be used on 24-120V and deliver up to 600A. The 600A rating can be met for the semi-customary 1 minute given the specs of the MOSFETs and heatsink but I am highly skeptical this controller would survive for long at 108V, much less at 120V (indeed, the one I have blew up in a 96V system...). It basically comes down to stray inductance (10-30nH/inch) and the switching speed of the MOSFETs. Even at a rather leisurely transition time of 500nS (0.5uS), 600A will induce somewhere between 12 and 36V per inch of wire in voltage spike. At a minimum, one should employ an RC or RCD snubber on each leg of the half bridge AND use switches rated for 2x the maximum supply voltage.
> 
> ...


Tesseract,
I was going to dissect the Kelly 14500A that went up in a ball of smoke and flame on my 'whitebird'... but the situation demanded a return for warranty reasons... so no ripping into the guts. HOWEVER, you mention the obfuscation of the info on the microchip, which lead me to believe it was either pirated, or a blackmarket supply... "KELLY" is a Chinese firm in mainland China with an office mailing box/supply house in Illinois... and I remember a company (that to this day I will not touch a computer that has such a board in it!) called PCChips that makes motherboards... they also were Chinese, and built boards for GateWay Computers with pirated BIOS chips... the companies in mainland and outlaying Chinese satellites have been doing this for years. I am sure if I had ripped the guts open on the 14500A I would have found similar!.. And now I am going to find out what the 14500B does for me... with a 108VDC system. (It is rated at max. 168VDC according to Kelly) Thank you for the really fine and detailed expose of the 12600, that was the controller Wen (Steven) Li at Kelly was trying to pawn off to me to replace my 14500A!!! But I got my warranty filled with a 14500B instead thanks to the company I bought it from... 'Electric Vehicles USA'. (The problem with that is that they like to hawk the cheap Chinese crap... to newbies like I was. Had to return a charger made by 'Zivan' that was shipped from China, and it was all chipped up and dog-eared on the connection rack ends... and the wrong plug attachment... I chose to go with a Russco instead from EVParts. 
"With time comes experience, with experience comes knowledge, with knowledge comes the desire to learn more and reach farther!... And the ability to say: NO!"


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## Tesseract (Sep 27, 2008)

TheSGC said:


> Ok, got it. My design does have a driver and when I get the time, I am going to get the gate resistor right for the proper timing. (I will get some help my uncle and his oscilloscope to get the gate drive squared down)
> 
> And a question on the cable lengths from controller to motor- I have three foot lengths at the moment, which doesn't seem to long but I will try to rearrange things to get it down another 1-1.5 feet smaller- Is three feet too long?


If the datasheet doesn't specify the recommended gate resistor (most modern IGBT modules do) then keep this equation in mind:

Rg[min] = (L/C)^0.5

Where Rg[min] is the minimum value of the series gate resistor to prevent ringing; L is the stray inductance of the wiring between the driver output and the gate terminal (20nH per inch) and C is the Cies spec, in nF. For example, if the driver is 6" away from the gate and the Cies spec is 10nF then the gate resistor needs to be 3.46ohms or higher in value. Ringing on the gate is a very bad thing, especially when driving it with the recommended 15V, as most IGBTs can only withstand 20V.

3' is a bit long, yes, but not unmanageable IF you join the cables to each other with plastic cable ties.


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## TheSGC (Nov 15, 2007)

I did a decent estimate of about 10 ohms on the gate, but I will make a better calculation when I have time.

Yeah, I thought 3 feet would be too long. I am locating the controller from one side of the compartment to the other (above the motor) so I should be able to loose at least a 1 ft to make 1.5 ft with the new layout. BTW, I am using stranded 4/0 gauge cable on this system and I will use tie wraps to keep them together.


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## Tesseract (Sep 27, 2008)

fugdabug said:


> ... Thank you for the really fine and detailed expose of the 12600, that was the controller Wen (Steven) Li at Kelly was trying to pawn off to me to replace my 14500A!!! But I got my warranty filled with a 14500B instead thanks to the company I bought it from... 'Electric Vehicles USA'....


The company that hired me to design them a controller was motivated to do so because they too have had poor experiences with the infamous Wen/Steven Li.

Also, so far as I know, no one has ever received a refund for a bad controller - only a replacement or an offer to "upgrade for the difference in price". This applies to Li's distributors, too, so they eventually get stuck with the loss. Of course, that will eventually decrease their willingness to carry Kelly products - who wants to sell crap that when it breaks you have to eat the cost yourself?

***

One other thing about the KDH12600 controller that I didn't even notice is that even the bus bars are woefully undersized for the current! For a 600A max rated controller the bus bar needs to be at least 1/4" x 1" (that's technically 400A continuous with a 30C temp rise... from just the bus bar conducting current! At 600A the temp rise will be 50C; acceptable but not ideal). The KDH12600 bus bars are only 0.110" x 0.625" - good for about 150A).

Also, though the circuit used in the KDH12600 is capable of regeneration - a half-bridge - this feature is not implemented. Series dc motors are notoriously difficult to implement regen with because their transfer function has two possible infinities in it (voltage output at zero load; current output at short circuit). No real excuse not to implement it anyway if using a microcontroller (it's much easier to implement the math required to handle the change-over from buck (motoring) to boost (regenerating) modes with an actual program than it is with a bunch of op-amps and RC networks.).


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## fugdabug (Jul 14, 2008)

Tesseract,
I really wish I would have opened up the 14500(A) and photo'd the guts... for display to the world.
I am not an engineer by any stretch of the imagination however I do get a grasp of what you are describing, I am doing everything I can to bring myself up to snuff on the calculations of component values for a given system. Educating oneself in an 'above the basics' level of electronics is a necessity at any level beyond 'put piece (a) to piece (b)...'. I am currently delving into Paynter's, "Introductory Electronic Devices and Circuits". So that will give you an idea of where this ol' mush-mind is... ~8). By the by, do you have a recommendation of controller manufacturers...? 
I am not positive, but I think I am looking at a failure for sure on the controller that was sent as a replacement. 
If it is in the final analysis the controller, I am going to autopsy it and photo completely, because with all the parts in my 'bin' or available to me it just may be able to be repaired should it come down to the 'autopsy' stage. I mean it is worth a try, eh? (I used to build systems for Data Control years ago, and was a lead instructor for them... and I build and destroy computer systems...). Should that not work I am still going to have to get a different (not a Kelly!) controller... so...


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## StevenLi (Oct 30, 2008)

Tesseract said:


> First off, thanks for the comments. Secondly, my intent here was not so much to bash Kelly (I tried to point out the good and the bad) but rather to use their controller to illustrate the sorts of things one needs to pay attention to if you want to "roll your own".
> 
> gottdi: I suppose it bears repeating that I am being paid to design a competing product to Kelly's, so I have no economic interest in helping Kelly out here...  That said my opinion on this in general is that, Kelly, like any other company trying to make a name for itself, ought to be pro-actively solving problems with their products, not relying on paying customers to do their beta-testing. Just my $0.02.
> 
> david85: thanks for the welcome. While I also have an economic interest in _not_ sharing too much of what I'm working on, I will share some of it.


Interesting. Have you paid? Should the controller be returned?
Apparently you have economic reason to piss here.
Good luck to get your controller done. I am looking forward to see it.
Do you want to see how many people used KDH12 successfully?


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## StevenLi (Oct 30, 2008)

Tesseract said:


> The company that hired me to design them a controller was motivated to do so because they too have had poor experiences with the infamous Wen/Steven Li.
> 
> Also, so far as I know, no one has ever received a refund for a bad controller - only a replacement or an offer to "upgrade for the difference in price". This applies to Li's distributors, too, so they eventually get stuck with the loss. Of course, that will eventually decrease their willingness to carry Kelly products - who wants to sell crap that when it breaks you have to eat the cost yourself?


 
Really??? Do you know how many people want to be Kelly distributors? In every single day? Pick a day, and I will send you a list!
What's the loss they stuck with? It seems you know much more than truth. 
What cost you eat????????? Kelly has sent replacement. And you need to return the controller!!!!!
Kelly's goal: Every customer got to get EV running well, no matter how much knowledge the customer has on electronics, no matter how much cost to Kelly. 
(On contrary, some super smart people may not get things done.... They show off and pissing rather than pursue truth....)


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## StevenLi (Oct 30, 2008)

fugdabug said:


> Tesseract,
> I was going to dissect the Kelly 14500A that went up in a ball of smoke and flame on my 'whitebird'... but the situation demanded a return for warranty reasons... so no ripping into the guts. HOWEVER, you mention the obfuscation of the info on the microchip, which lead me to believe it was either pirated, or a blackmarket supply...


Why did you insist that was a KDH14500B??? You knew it wasn't. The distributor bought KDH14500 (not even "A", please note) from Kelly, and Kelly replaced it with KDH14500B for you, for free. What can a manufacturer do more than that? 

Do you know anybody uses the same micro for this kind of controller? Do you know anybody uses the same mechanical structure? Do you know anybody got functions even close to Kelly's? Do you know anybody got layout similar? Have you seen any copycat moving up with such steady pace, and reponse to customer so quickly? 

It seems you regard yourself kind of high.

Why obfuscation? That's not really a smart question with people read this string...


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## StevenLi (Oct 30, 2008)

Tesseract said:


> ...One other thing about the KDH12600 controller that I didn't even notice is that even the bus bars are woefully undersized for the current! For a 600A max rated controller the bus bar needs to be at least 1/4" x 1" (that's technically 400A continuous with a 30C temp rise... from just the bus bar conducting current! At 600A the temp rise will be 50C; acceptable but not ideal). The KDH12600 bus bars are only 0.110" x 0.625" - good for about 150A).


50C at what condition? Bare copper with heat sink?
Looking forward to see your controller with the copper bar you like. I am expecting to see it as a world record. Not bad.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> ...continued.
> 
> As seen in Kelly-4.jpg, the wires from the two circular connectors are not shielded in any way from the intense H field produced by the controller when switching even modest amounts of current (say, 50+ amps). Such could easily cause the microcontroller to hang.


The fact is Kelly controllers always pass EMC test with flashing, with standard test organizations, as well as with customer tests.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> ...continued.
> 
> The label on the KDH12600 indicates it can be used on 24-120V and deliver up to 600A. The 600A rating can be met for the semi-customary 1 minute given the specs of the MOSFETs and heatsink but I am highly skeptical this controller would survive for long at 108V, much less at 120V (indeed, the one I have blew up in a 96V system...). It basically comes down to stray inductance (10-30nH/inch) and the switching speed of the MOSFETs. Even at a rather leisurely transition time of 500nS (0.5uS), 600A will induce somewhere between 12 and 36V per inch of wire in voltage spike. At a minimum, one should employ an RC or RCD snubber on each leg of the half bridge AND use switches rated for 2x the maximum supply voltage.


You just don't know other better ways. As I pointed out before, RCD was implemented in Kelly $99 controller. Buy one and study...Don't argue with refund in the case, ok? 
In fact, battery cable length doesn't matter to Kelly Controller.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> ...continued.
> 
> 
> Finally, Kelly-3.jpg shows the underside of the controller. The most interesting thing to note here is that while all of the drains are bolted to a copper buss bar, all of the sources are merely soldered to the PCB. If this PCB were clad with 2oz copper (and this one definitely uses 1oz), the trace for the sources would need to be 13.6cm wide (~5.4") to carry 600A even allowing for a 30C temp rise!?!


Wow!!! That's great finding! Looking forward to see you bond/solder sources to somewhere else.
Does it need to carry 600A? Really?


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## StevenLi (Oct 30, 2008)

Tesseract said:


> ...continued.
> 
> Finally, there does not appear to be any isolation between the microcontroller and the MOSFETs, hence why a separate, _isolated_ power supply is needed.


Wow! Great engineer! For what? Can isolate throttle pedal from high voltage? communication port? or micro?

By the way, Kelly KDHA and KDHB are completely isolated...Not by your advise though.

It's easy to piss...show what you've done! Please!


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## vgslimo (Oct 21, 2008)

steven, i have been following this thread and others because i was still interested in your controller, but now that your here being so arrogant and noisy it seems like others were stating the truth that you really treat your customers badly. if i were you, from a business stand point i would concentrate on calmy explaining your product and how it is meant to function and refute with intelligence and simple to understand language so that those of us that haven't bought a controller yet, (which is actually probably 90% of people reading this) don't think your just an arogant ass.


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## Guest (Nov 2, 2008)

He's human too. Arrogant people can piss anyone off not matter how professional or not. Steven does a very good job explaining and you only need to ask. His product is like any other in that some can be bad. You must realize that mechanical products do break or consumers hook them up wrong. Burn them up and expect a refund or replacement. If you happen to be confused you need to clarify so you don't MAGIC SMOKE your controller. I agree that some reserve needs to be made here. Kelly is not new but new to us. Making a controller for use in an EV is no easy feat. I see Kelly as actually making controllers for sale and not just bad mouthing others controllers. He actually says good things but you all don't ask and don't listen. I have had nothing but excellent customer service and I do have things explained to me very clearly. As far as Curtis controllers they have had plenty of shares of bad controllers. Same with Zilla, Alltrax and Logosystems, and others. Even Zapi had their share. The H3 was a bad cookie but the H2 is still an excellent SepEx controller from them that will work very well in an on road EV. High power too. Not a Zilla but still very good. The H3 is fine as long as you don't use the regen function or plug brake function. 

Kelly has a good product and they stand behind that. Curtis does, Alltrax does, Logosystems does, you even have folks rebuilding Raptor controllers. No one is out to screw anyone. We all want a good product and I feel Kelly has a decent one at a decent price. But remember to match your controller with our motor. Never use an underpowered controller for your motors needs. If anything use an over powered one and tone down the program if yours happens to be a programmable controller. I am pleased with Kelly products and I am pleased with their customer service and exceptional warranty issues. I would never expect them to refund the money but I would expect a replacement if the product is faulty. If the customer is at fault I would not expect any warranty to be honored but guess what, they honor the warranty even if it really is a customer screw up. Can't beat that period. Give them a chance and back off. 

Pete : )




vgslimo said:


> steven, i have been following this thread and others because i was still interested in your controller, but now that your here being so arrogant and noisy it seems like others were stating the truth that you really treat your customers badly. if i were you, from a business stand point i would concentrate on calmy explaining your product and how it is meant to function and refute with intelligence and simple to understand language so that those of us that haven't bought a controller yet, (which is actually probably 90% of people reading this) don't think your just an arogant ass.


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## vgslimo (Oct 21, 2008)

gottdi, thats the first time i've seen a post like yours with a good review and i actually was only trying to let him know that if all he says as the business owner is rough and arogant it will lend credence to all the nay sayers posts. i agree completely with the tone of your post about customer fault in the bargain and understand pissed customers which is exactly why i informed him i was still interested in his product. but if the owner of a business or head guy whatever is a jerk or arrogant why spend your money with him when you can just buy from someone else? it was meant to be a helpful suggestion. if you are the front man then BE the front man. and there have been several comments about his attitude toward customers and noone has contridicted them so it does add credence to what they say when he display's the same for all the world to see. it's just bad business.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Yeah, I imagine there are a bunch of ways to optimize the code which may make this do-able. Programming those little buggers is definitely not my strong suit - I have a stack of books on them but haven't managed to get through a single one... FWIW, I am looking at the ATTiny461 for my controller design as it has the fast hardware PWM built in. Not sure if I will be able to cram all of the code needed for a 2-quadrant motor controller (forward motoring and regeneration) into the 4k of memory... maybe if I leave out all of the comments...


Wow! ATTiny461 is your creativity? How many people used it? 
It says "dum" & "cheap" to me. 
It's a good for people pissing and copying, I guess.
"Economic reason" does look deal to you, baby!


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## StevenLi (Oct 30, 2008)

vgslimo said:


> steven, i have been following this thread and others because i was still interested in your controller, but now that your here being so arrogant and noisy it seems like others were stating the truth that you really treat your customers badly. if i were you, from a business stand point i would concentrate on calmy explaining your product and how it is meant to function and refute with intelligence and simple to understand language so that those of us that haven't bought a controller yet, (which is actually probably 90% of people reading this) don't think your just an arogant ass.


Unreasonably claim "pirate" isn't something to say with ease....Won't piss you off? I am arrogant enough to believe Kelly is doing own unique design, good or bad.
Have you seen arrogancy with all those claims? Have you seen "economic reason" is the ultimate reason for somebody? If only people say some true!


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## vgslimo (Oct 21, 2008)

it might piss me off, but rather than alienate any future clientelle by displaying to the world he got to you and if they are unhappy with your product you will attack them too, don't you think it better to show sorrow at his loss and then calmly explain for the world to see that your reasoning is sound and this is how my controller works good and so on. since you already have a patened or copywrited product it should be easy for you to rationally and calmy explain why your controller is the best without giving away trade secrets. sound business advice is always try to empathise with your customer, always appologise even when your not wrong,( i'm sorry you feel that way...) and explain calmy what you can and can not do for them.. many customers are irrational it's your job to remain calm since at least you have their money. i'm not trying to be rude but are you using a translate program? because some of your syntax or wording is not making sense to me. could be a slight language barrier as well as culturaly since we americans are used to a different way of business than other parts of the world.


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## StevenLi (Oct 30, 2008)

vgslimo said:


> steven, i have been following this thread and others because i was still interested in your controller, but now that your here being so arrogant and noisy it seems like others were stating the truth that you really treat your customers badly. if i were you, from a business stand point i would concentrate on calmy explaining your product and how it is meant to function and refute with intelligence and simple to understand language so that those of us that haven't bought a controller yet, (which is actually probably 90% of people reading this) don't think your just an arogant ass.


Things are the guy isn't saying the truth.
"No refund made ever....Distributor loss... doom to die..." and some technical claims. Those are not true. Too many assumptions and arrogancy.


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## StevenLi (Oct 30, 2008)

vgslimo said:


> thats the first time i've seen a post like that with a good review and i actually was only trying to let him know that if all he says as the business owner is rough and arogant it will lend credence to all the nay sayers posts. i agree completely with the tone of your post about customer fault in the bargain and understand pissed customers which is exactly why i informed him i was still interested in his product. but if the owner of a business or head guy whatever is a jerk or arrogant why spend your money with him when you can just buy from someone else? it was meant to be a helpful suggestion. if you are the front man then BE the front man. and there have been several comments about his attitude toward customers and noone has contridicted them so it does add credence to what they say when he display's the same for all the world to see. it's just bad business.


The post was there so many days. I didn't see you noticed him things should be noticed.
I will be nice to everybody to certain point. I did so much favor (arrogant to believe that) to a customer, free parts, suggestions removing redundant parts from paying, exchange with more expensive controllers, send replacement before receive return for urgent needs..The exchange is claim of "pirate" and "cheap". Open the controller and never return! Nothing hurts more than that!


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## vgslimo (Oct 21, 2008)

StevenLi said:


> The post was there so many days. I didn't see you let him know things should be noticed.


sorry, i don't understand what you mean. i was responding to the post directly above mine.


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## StevenLi (Oct 30, 2008)

vgslimo said:


> steven, i have been following this thread and others because i was still interested in your controller, but now that your here being so arrogant and noisy it seems like others were stating the truth that you really treat your customers badly. if i were you, from a business stand point i would concentrate on calmy explaining your product and how it is meant to function and refute with intelligence and simple to understand language so that those of us that haven't bought a controller yet, (which is actually probably 90% of people reading this) don't think your just an arogant ass.


Looks to me he's hired, or trying to be hired, to claim things like that.


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## StevenLi (Oct 30, 2008)

vgslimo said:


> sorry, i don't understand what you mean. i was responding to the post directly above mine.


You said you like to remind him certain things...But you didn't in many days.
Instead, you proposed to be his partner, didn't you?


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## vgslimo (Oct 21, 2008)

StevenLi said:


> Looks to me he's hired, or trying to be hired, to claim things like that.


yes but he told us that and most of us are smart enough to know to use caution when listening but he is very easy to understand and cautions us himself that he is competeting with you. so it could come down to politics for some people when they decide your controller or his? tell us how great your product is and maybe answer concerns that people pose and you could win in the marketplace. tell us we are just bad customers and we take our money walking somewhere else.


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## vgslimo (Oct 21, 2008)

StevenLi said:


> You said you like to remind him certain things...But you didn't in many days.
> Instead, you proposed to be his partner, didn't you?


not at all. this for sure is a language gap issue. quote the part you are questioning and i will try to answer.


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## StevenLi (Oct 30, 2008)

vgslimo said:


> it might piss me off, but rather than alienate any future clientelle by displaying to the world he got to you and if they are unhappy with your product you will attack them too, don't you think it better to show sorrow at his loss and then calmly explain for the world to see that your reasoning is sound and this is how my controller works good and so on. since you already have a patened or copywrited product it should be easy for you to rationally and calmy explain why your controller is the best without giving away trade secrets. sound business advice is always try to empathise with your customer, always appologise even when your not wrong,( i'm sorry you feel that way...) and explain calmy what you can and can not do for them.. many customers are irrational it's your job to remain calm since at least you have their money. i'm not trying to be rude but are you using a translate program? because some of your syntax or wording is not making sense to me. could be a slight language barrier as well as culturaly since we americans are used to a different way of business than other parts of the world.


Calm explanation can work for people willing to listen. It won't work for biased or arrogant people. I have to say I saw the most arrogant person in the thread.
I am willing to talk with people appreciate truth...That's it.
Do you mean I read "arrogance" of the poster is because of my way? And you don't read arrogancy with your american way?


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## vgslimo (Oct 21, 2008)

StevenLi said:


> Calm explanation can work for people willing to listen. It won't work for biased or arrogant people. I have to say I saw the most arrogant person in the thread.
> I am willing to talk with people appreciate truth...That's it.


this forum is read, WORLD WIDE, 90% of people reading don't even join the forum, they just read it. your entire future customer base is out here looking at your words. if you don't sound professional, americans at least, probably will choose a competitor to buy from since they won't want to take a chance of having a problem and then have to talk to you. if your goal here was to ruin your business then by all means bash anyone you want. but people bashing you, have nothing to lose. think about just talking about how your mossfet were certified by testing at continous 600 amps for 2 years, or whatever the truth is. tell us that his concerns over the size of your bars is unfounded because you use some special routing of the amperage that he dosen't understand. tell us good things while answering the concerned area and you have a chance at earning our business. let us watch you rant and rave however and you surely will lose business world wide.


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## Tesseract (Sep 27, 2008)

Oh boy... looks like somebody's all riled up here... Yes, I am being paid to develop a new motor controller by someone who currently, albeit very reluctantly, sells Kelly products. And only with the recommendation that they be seriously derated (in other words - this company point blank tells customers to disregard the voltage and current ratings claimed by Kelly). 

Folks, whatever merits there might be in my technical arguments keep in mind that somebody is disgusted enough with the controllers offered for sale right now that they are willing to pay someone to develop a new one from scratch! It's one thing to b!tch and moan about the controller selection and quite another to pony up cold hard cash to do something about it!

StevenLi, I noticed you have made some 15 posts in this thread but have yet to address what I feel are the most serious deficiencies I identified in the KDH12600. I'm interested in hearing your counterarguments to my assertions, even if you can't make them in a civil and professional manner.

1. How do you make sure the paralleled MOSFETs share current equally during the switching transitions? There are ways to do it that would not necessarily be evident just by looking at the PC board but I'm curious to see if you know what they are.

2. What is your reasoning for stating on the label for the KDH12600 that it can be used at up to 120V when the MOSFETs inside are only rated for 150V?

3. How is current in the MOSFETs sensed? Does the microcontroller deal with an overcurrent fault or is there some sort of local (hardware) response?

4. How are spikes from stray inductance addressed? Are you, in fact, relying on the MOSFETs "avalanche rating"?

5. Does the microcontroller share a common ground with the battery pack - i.e., because of the gates being driven directly with, for example, a level shift IC such as the IR2110?


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## 280z1975 (Oct 2, 2008)

StevenLi said:


> Calm explanation can work for people willing to listen. It won't work for biased or arrogant people. I have to say I saw the most arrogant person in the thread.
> I am willing to talk with people appreciate truth...That's it.
> Do you mean I read "arrogance" of the poster is because of my way? And you don't read arrogancy with your american way?


StevenLi ... I am one of many "people wiling to listen" if you could calmly explain things. I am like many here who want to buy the best controller and if you can make the argument that your Kelly Controller is right for me I would buy it.

The contoller is the SINGLE most important part of an EV, it's brain to make a comparison. We only want to give our EV's the best brain. So I agree with vgslimo, please do a post where you calmly explain yourself.

-Gregg-


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## Tesseract (Sep 27, 2008)

gottdi said:


> He's human too. Arrogant people can piss anyone off not matter how professional or not. ... I see Kelly as actually making controllers for sale and not just bad mouthing others controllers.


Valid points, Pete.

That said, don't you think it just a bit odd how rapidly Kelly has come out with "improved" versions of its controllers? Would it be unreasonable to conclude they have used the customers of their earlier models (such as the KDH12600) as guinea pigs/beta testers? I bet if I crack open a 14500B I'll find optoisolators in the gate drive, higher voltage rated MOSFETs and a whole bunch of other "improvements" that should have been done in the first place, or at least not at the expense of paying customers. Even still, people are managing to blow them up (e.g. - fugdabug).

Now, I understand the skepticism that inclines all of us to take a controller manufacturer's specs with a grain of salt but I still think that unless the controller manufacturer especially enjoys lawsuits they really ought to make sure that a 120V/600A controller can survive operating at 120V while delivering up to 600A. Sure, it is reaonable to state a time-limit for the peak current - it requires either an insanely large heat sink or liquid cooling to maintain that current rating continuously - but if it says it can handle 120V, I darn well better be able to connect it up to a pack of (10) 12V batteries without it frying.

Just sayin'.


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## fugdabug (Jul 14, 2008)

StevenLi said:


> Why did you insist that was a KDH14500B??? You knew it wasn't. The distributor bought KDH14500 (not even "A", please note) from Kelly, and Kelly replaced it with KDH14500B for you, for free. What can a manufacturer do more than that?
> 
> Do you know anybody uses the same micro for this kind of controller? Do you know anybody uses the same mechanical structure? Do you know anybody got functions even close to Kelly's? Do you know anybody got layout similar? Have you seen any copycat moving up with such steady pace, and reponse to customer so quickly?
> 
> ...


I will let the degrading tone you use speak for itself, Mr. Li. Excuse me but the inventory number of the item I ordered ORIGINALLY was listed as a 14500B, THAT is why they replaced it with the same. I was ignorant that it was a 14500(a) until I started questioning the model when I saw postings about the 14500 series.
Now as for not being a smart 'word' (not question) to use in this group I will leave that to the group to answer.
Don't get personal Steven. This is a matter of business... involving MY money, and a product I thought I was buying that would work. And I didn't buy it from your firm, I bought it through another dealer... By the way, I checked and rechecked my system, there was a loose wire on the power ground to the 12V on the controller... so now I get a green light... the controller STILL doesn't let the power through to the motor. 
So I am going to do just what I said to you in my letter to your rather terse and demeaning letter: I am going to buy a 'crappy' American (yes, it is made in Livermore California) Made Curtis controller... 
Look if you want to keep customers in this country, or anywhere else for that matter,.. you had better realize it is easier to catch flies with honey and that vinegar is a turn-off.
That is my word on the matter.


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## fugdabug (Jul 14, 2008)

Well gang, ohm tested the pot's microswitch and the pot itself. Found a loose wire at position 3 of the aviation plug. I replaced the pin and re-soldered a new piece of wire with fork connector and replaced the plug. I ran in the house and grabbed the mini-vid camera and was hoping to have a vid for you all to see of a successful run up the driveway. But fate and fortune were not such that it was to be. I even had my neighbor over to look at the wiring situation (although not an engineer he too is a 'wire-junky'). And we were in agreement all things being equal the controller was not allowing juice through, lights on or not... programming ability or not... there is something amiss in that box. So my next choice, next Spring will be to replace it with a Curtis... Unfortunately I have to wait on doing a complete rebuild because Winter is a-moving in again up here. Of course I am planning on buying it this year (as a write-off, Whitebird is going to be used for my business as well! What better way to spread the word about EV?). I will have the time then as well, hopefully, to gut the original wiring harness and do something about the steering hydraulics and I just might even put in a DC/DC converter... I ordered up a reversing contactor a week or so ago as well to avoid the nasty 'knee-jerk' back-up... could use it to scare the Hades out of ol' farts at Wally-world~ I have a couple of other tricks up the sleeve yet and if they don't work I will go ahead with the 'autopsy' (complete with photos and dissection vid... in the labor-a-tory).


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Valid points, Pete.
> 
> That said, don't you think it just a bit odd how rapidly Kelly has come out with "improved" versions of its controllers? Would it be unreasonable to conclude they have used the customers of their earlier models (such as the KDH12600) as guinea pigs/beta testers? I bet if I crack open a 14500B I'll find optoisolators in the gate drive, higher voltage rated MOSFETs and a whole bunch of other "improvements" that should have been done in the first place, or at least not at the expense of paying customers. Even still, people are managing to blow them up (e.g. - fugdabug).
> 
> ...


Well, not blow up yet! 
There are millions reasons for controller not work. As I predicted before, people can't make things work if assume too many things.


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## fugdabug (Jul 14, 2008)

You know folks we have engineers among us here, and we have folks from all over the world. And it is not an "American-only" site... by any means!!! I didn't come to this site to ruin a company (companies ruin themselves!) or to demean a person or what ever... I came seeking to know what I can do to get my machine working the best way possible for the set-up I have and pose questions of ideas... and to learn from folks like Tesseract who started the thread with his wonderful expository dissection. AND he knows of that which he speaks... 
It is one thing to speak to a problem and a whole other thing to speak to ones personal stance. 
So... just a personal note: I think we are trying to figure out WHAT the problem might be with these products and if we can overcome them... (AND yes I included extraneous materials in my posting(s)... because I felt it was showing how one can try to focus on a solution and only get 'OBFUSCATION'... The KDH12600, like my original KDH14500 was rated for service at a voltage 'range'. WHEN a product says it is servicable for a system that is 120VDC or 144VDC it darn well better work at that voltage... or the manufacturer has mis-represented the product. 
I personally think the controllers in question should be taken to the Consumer Reports labs and tested thoroughly! In fact I just may contact them tomorrow (Monday here in the 'States) and see if I can't get them to run some tests on these beasties, in particular a controller rated at 120VDC and a controller rated at 144VDC! At least we would have a varification by a testing facility that is trusted and reliable...


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Valid points, Pete.
> 
> That said, don't you think it just a bit odd how rapidly Kelly has come out with "improved" versions of its controllers? Would it be unreasonable to conclude they have used the customers of their earlier models (such as the KDH12600) as guinea pigs/beta testers? I bet if I crack open a 14500B I'll find optoisolators in the gate drive, higher voltage rated MOSFETs and a whole bunch of other "improvements" that should have been done in the first place, or at least not at the expense of paying customers. Even still, people are managing to blow them up (e.g. - fugdabug).
> 
> Just sayin'.


Sorry we are not smart enough to know everything at the first place. We take customer feedbacks, and meet their needs. By the way, nothing was coming from your analyse though. You analyse came after Kelly got those done.
Hope some super smart people will produce perfect controller on the first place, sincerely.


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## JRP3 (Mar 7, 2008)

Steven is coming off very poorly here. Use logic and facts to counter your critics, not personal attacks. After Steven's replies here I'm even less inclined to purchase a Kelly controller. Probably not what he was trying to achieve.


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## Guest (Nov 2, 2008)

Steven is coming off a bit but you know who is coming off worse. His customers. If its business then all need to act as business men/women and not anal hot heads. Fact is there are many companies with controllers that at one time or another failed and just because this one happens to be from China the hot heads here are blasting extra hard. Well I hate to say it but the Curtis may be assembled here in the good OL USA but the parts come from China or other far away countries and for sure NOT USA. So hot heads please cool the jets here on this one. Where are the parts from your computer made? China. I don't hear you blasting them. Building a controller is not an easy thing and I have heard about plenty of Curtis Controllers making that MAGIC SMOKE. I say user error and not controller error. We are actually using controllers not designed for the application we use them for to begin with. Some have been trying and a few have had success but they had success with our help and yes we are the beta testers. If it happens to be new and we want to try we are doing so with the knowledge that it is a test or prototype. It does not matter if we purchased it or not. I did that with my Kelly and if it ever smokes on me I will figure it a good lesson and move on and not get nasty. I knew it was a test. I was willing to spend the money and so were all who purchased one. No different than with a Curtis. Lots of bad mouthing about them because of the noise they make even though they explained why it was done that way. It was found that some of Kelly controllers were over rated but that they were not bad. It is business. They have fixed it. Did you who purchase one and had it go bad even bother to ask? Or just get hot under the collar. Mine is rated at 600 amps but was down rated to 500. That is fine. 

I'd say ask if yours has been derated and if so maybe if you ask nice they can replace it with a new upgrade that is rated at what you want. Ask. Can't hurt. I do all the time. I get better customer service from these guys than most local or US businesses. At least they are willing to work with you if you just have the decency to ask. Yea it's your money but it is his too that's on the line. Kelly has more on the line than you all or me. I'd say play nice at least they don't ignore you like other companies do. 

JRP3, don't base your decision on purchasing because one person from within Kelly got attitude from being blasted from a bunch of little hotheads. I am sure that is not a very logical choice. : )

I am talking to Steve off line about handling ones self in public. Other here should do the same. 




JRP3 said:


> Steven is coming off very poorly here. Use logic and facts to counter your critics, not personal attacks. After Steven's replies here I'm even less inclined to purchase a Kelly controller. Probably not what he was trying to achieve.


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## JRP3 (Mar 7, 2008)

gottdi said:


> Steven is coming off a bit but you know who is coming off worse. His customers. If its business then all need to act as business men/women and not anal hot heads.


The problem is that it's up to the business to keep customers and gain new ones, and they do that with good products and good service. Customers come in all shapes and sizes, and yes some are a-holes. However, no one in this thread was being out of line until Steven showed up attacking. This thread was a rational discussion of some of the potential weaknesses of kelly controllers. This is also not the first time we have heard of problems with them.


> JRP3, don't base your decision on purchasing because one person from within Kelly got attitude from being blasted from a bunch of little hotheads. I am sure that is not a very logical choice. : )


Of course not, I was skeptical of these controllers because of what I would consider high failure rates. When customers spend their money and don't get what they paid for, I am not going to blame them for being "hotheads". The fact that Kelly is redesigning controllers tells you they weren't made properly in the first place and probably should have had more testing before they went to market. I hope they fix all this but am not willing to be a product tester for them at this time.


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## Guest (Nov 2, 2008)

How quickly, Nope. It was not quick. You know what they found. Kelly rated my controller from 18 to 90 volts. That 90 volts is peak and if you go over that you MAGIC SMOKE the controller hands down. Now you take some smarty pants person who thinks they know it all and decides that since it is rated at 90 it must be able to handle 90 even though it's sold as a 72 volt controller. Wow, to what surprise when that MAGIC SMOKE comes billowing out when they hook up 15 6 volt batteries fully charged to that controller. Well it did say max is 90. But the smarty pants did not do the homework required and he actually has a pack that when fully charged is more than 90 volts. Now he gets real hot and pisses and moans to the company that the controller is bad and needs a replacement. Well Kelly controller requires the old one be sent back then they will send a replacement. Done deal and because the smarty pants still has no clue the controller is hooked up once again and guess what. MAGIC SMOKE AGAIN. Wow it must be the controller. Well Kelly took them apart and found that they were over rated and took care of the matter. No biggie. Others did that to. So this shows that the customer was at fault and not Kelly but Kelly got the brunt and the business was hurt. It was not because of faulty parts but faulty customers. Sure there were under rated controllers but they always honored the warranty and found the problem. Now in my book that is how a business should work. Just think if all products were to work perfectly when first introduced to the public we'd all be happy campers. What about VISTA. What a disaster that was and the expense of the customer. Same with thousands of other products. Products are not perfect at first and problems do arise and if the company is wanting a market share they will take care of the problem. Kelly is doing just that. It is at their expense. Not yours. If Kelly did not honor the warranty and did nothing to fix the problems reported I would say Kelly should just go away but they do honor the warranty and they are fixing the controllers and not because you guys here have taken them apart to dissect them for your own business. Seems like you are all trying to gain a foot hold at someone else's expense. Take what works from others and make one and say it's your own. Now that's business the AMERICAN way. Gates did that.

Sorry to say but Kelly has built a damn good controller. Like it or not. 

Pete : )




Tesseract said:


> Valid points, Pete.
> 
> That said, don't you think it just a bit odd how rapidly Kelly has come out with "improved" versions of its controllers? Would it be unreasonable to conclude they have used the customers of their earlier models (such as the KDH12600) as guinea pigs/beta testers? I bet if I crack open a 14500B I'll find optoisolators in the gate drive, higher voltage rated MOSFETs and a whole bunch of other "improvements" that should have been done in the first place, or at least not at the expense of paying customers. Even still, people are managing to blow them up (e.g. - fugdabug).
> 
> ...


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## JRP3 (Mar 7, 2008)

Frankly your attitude isn't helping Kelly very much either. Comparing Kelly controllers to crap like Vista isn't a great selling point. Millions of people won't touch Vista because it's not ready for use. I'd like you to show me a single thread where someone took a 72 volt Kelly controller and hooked it up to 90 volts as you claim, especially since that's an unusual voltage for ev's.


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## 280z1975 (Oct 2, 2008)

gottdi said:


> Steven is coming off a bit but you know who is coming off worse. His customers. If its business then all need to act as business men/women and not anal hot heads.


I can understand Steven's being mad, but his customers are unhappy because what they bought didn't last or live up to their expectations. I will agree that many of the expectations of customers are higher than they should be, but from what I have read the expectations here are within what I think is quite reasonable for the purchase of a controller



gottdi said:


> Fact is there are many companies with controllers that at one time or another failed and just because this one happens to be from China the hot heads here are blasting extra hard. Well I hate to say it but the Curtis may be assembled here in the good OL USA but the parts come from China or other far away countries and for sure NOT USA. So hot heads please cool the jets here on this one. Where are the parts from your computer made? China. I don't hear you blasting them.


I have no problem with stuff from China as you are correct, almost all the electronics come from there. But when I do have a problem with the quality that can come from there with certain things. Just read the threads on LIFE4PO batteries. Of course if Kelly would like to sell in Europe they must remember that ALL consumer items here carry a minimum 2 year warranty. So it better last (when used right). When I buy something for a car I generally expect it to last at least 5 years or 75,000 miles.



gottdi said:


> ... snip... If it happens to be new and we want to try we are doing so with the knowledge that it is a test or prototype. It does not matter if we purchased it or not. I did that with my Kelly and if it ever smokes on me I will figure it a good lesson and move on and not get nasty. I knew it was a test. I was willing to spend the money and so were all who purchased one.


Were these controllers in question purchased as new or as sellable prototypes? I know from your posts that you have ben working with Kelly on your car and controller, but I thought that was a special sitation. If I were to buy something as a sellable prototype I better get it at a cheap price or the guarantee that if/when it breaks I can have a replacement. 



gottdi said:


> No different than with a Curtis. Lots of bad mouthing about them because of the noise they make even though they explained why it was done that way. It was found that some of Kelly controllers were over rated but that they were not bad. It is business. They have fixed it. Did you who purchase one and had it go bad even bother to ask? Or just get hot under the collar. Mine is rated at 600 amps but was down rated to 500. That is fine.


For you that might be fine, but for others to find out what they bought wasn't represented correctly. If I were in Steven's shoes and found out my controllers were sold overrated I would either offer to upgrade them for free or refund part of the sell price to compensate. How would you feel if you bought 100k tires that only really went 70k, not to happy ... see my point.



gottdi said:


> JRP3, don't base your decision on purchasing because one person from within Kelly got attitude from being blasted from a bunch of little hotheads. I am sure that is not a very logical choice. : )


Like JRP3, I am using what goes on in the forums for my basis in choice. Why? cause first hand experince is quite valuable and is why most of us read these forums. At the moment I am leaning toward a Curtis controler, not because of where it is made, but because of the overall feedback I've read here and other places. That isn't even taking into consideration this thread. 

I take much of what Tesseract with a grain of salt because I know his financial motivation behind what he is doing. But I am also glad he has pointed out the lackings of the Kelly controler (and the Curtis at times) along with the things they have done right. He's opened up the discussion on the inherent faults that lie within todays current controlers and is forcing the development bar and standards to which these are build to be that much better. 

With that said, Tesseract, if you are able could you divulge if your controler is being developed for the general market, or the oem market? and if for the general market, possiable market arrival time?

For Steven, if you can without exposing design secrets, refute or defend the design of your controlers? If you you were to refute what Tesseract has said and demostrate the quality of the controler, I, along with others, would be very tempted to consider your controler.

-Gregg-


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## Guest (Nov 2, 2008)

It is up to the company to keep customers and gain new one. They do have a good product but it must be operated within parameters and many are not. Hence the MAGIC SMOKE syndrome. Not really a fault of Kelly. However they do want a good product and it is required to change the ratings so they will handle the excesses we put upon the controller. Testing is usually done in a controlled setting and usually within normal parameters they will pass the tests with flying colors. Mine is still doing just fine. It was one that was derated but it's still doing fine. I am not bitching because I am going to get a better one. 

Yes it is being out of line to take a product and dissect it to make one for another company. When I mentioned that the things that were found within the controller should be changed I said why not send that info to Kelly so they can fix it if its bad. They said because it would conflict with his building a controller for another business he was hired to build. If he were hired he has no business digging into another product to take what they have and incorporate into their own. That is not building that is stealing. He refused to make those things known but he publicly stated them here. I just nudged Steven over here to see. That practice would make any one REAL PISSED and Steven has that RIGHT TO BE PISSED. As for the fixes of Kelly controllers it was done before this event took place so this event only PISSED him off. I stand behind him on that. We should all be wanting to have a company build a DAMN good controller that is affordable for the masses and yet we if we find something that may make it better we hoard it for our selves and won't let it go.

It's not the first time we have had problems with Curtis or Zilla or any other controller. One of late was a Raptor. Why pick on Kelly? CHINA SYNDROME is my guess. 

It's not rational when you don't and won't share yet publish on a public forum. 

Kelly has had no higher of a failure rate than any other controller I have researched. Actually I think one may have had a higher failure rate and that was Zapi's H3. Not any thing else but the H3 used for Regen. But again those were used with series motors without interpoles. It was not the fault of Zapi but that fact that no one yet knew that you really need interpoles on the motor and that the timing be moved back a bit. Without interpoles and without timing changes it would smoke em. They since pulled that one but still use the Zapi H2 today for the controller that will provide regen but again you need at least interpoles and timing changes to keep it alive. 

I too hope the fixes are spot on and that they will have an excellent future. I will however help because I feel that they are truly trying. I'd more expect Curtis to be perfect. But again Curtis is for forklifts and golf carts and NEV,s. Not hot rod electric cars weighing in at 4500 pounds and expected to move down the track at break neck speed. We as customers ask a bunch and usually will put the product through more than it was ever designed to do. If they get the controller to do what we will put them through then they will be the king of EV controllers. I think that is what they are after. 

By the way, as a computer user you are beta testing every new operating system that comes out. We always want them to test and testing is done but without real world experience nothing will ever get feted out. It requires that a product be put in the hands of the user and the user will find problems that the company will then fix. That is how all products get better. If all products had to be perfect from the start you'd never have anything to buy. That is how business goes. No matter how ready you think something is it is never ready enough. : )




JRP3 said:


> The problem is that it's up to the business to keep customers and gain new ones, and they do that with good products and good service. Customers come in all shapes and sizes, and yes some are a-holes. However, no one in this thread was being out of line until Steven showed up attacking. This thread was a rational discussion of some of the potential weaknesses of kelly controllers. This is also not the first time we have heard of problems with them.
> 
> Of course not, I was skeptical of these controllers because of what I would consider high failure rates. When customers spend their money and don't get what they paid for, I am not going to blame them for being "hotheads". The fact that Kelly is redesigning controllers tells you they weren't made properly in the first place and probably should have had more testing before they went to market. I hope they fix all this but am not willing to be a product tester for them at this time.


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## StevenLi (Oct 30, 2008)

Thanks for sincere oppinion.
First of all, personal attach came from personal attack...

1. How to work at 120V.

We are adjusting new controllers to 135-136V shutdown. Obviously there will be some measurement error. We are fine adjusting each controller to get value as precise as possible. I don't expect new controllers will be off by more than a couple of volts.


The controller does have high side mosfets working similar to freewheeling diodes, but dissipate much less heat.

Anyhow it comes to spikes on battery line. We put dozens 0805 caps that absorbes >10MHz noise, spreaded. We put dozens of 1210 ceramic caps to absorb noise >1MHz. We put many low impedance lytic caps to absorb <1MHz noise. Here just to give a rough idea of frequency range of capacitors. The line isn't that clear at real life though. But anyhow you have to max caps, with calculation or simulation how many you need.

When caps with all frequency ranges were spread, with enough volume and proper positioning, they can absorb spikes.

By the way, multiple smaller cap usually do better on frequency response than few big cap.

You should be ok As far as the spikes on bus line is within 150V. We placed caps with the goal.

Ceramic caps double it's capacitance with same size every two years. So keep an eye on new one come out. You may need less caps. (Kelly won't reduce components, but use it as reliability and performance improvement)

If you read artical written 5 or 10 years ago, you may rethink their suggestions on capacitors, such poly caps. Right now they are not able to compete with ceramic caps on anything for <250V.

The good thing about using caps instead of other approach: >99.9% energy will be recovered.

One big problem with textbook is that they can be outdated. Ceramic caps (X7R for most applications) come up on performance, and come down with price so quick...Consider it on the first place. 

2. Synchronize multiple mosfets
It's difficult to drive more than 8 mosfets with single gate driver. The ringing and noise can be huge.
Personally I don't think the delay is a big concern..electricity travel fast, should be in nano seconds range for 6 inches. The problem is ringing and noise.
Kelly use segments. If you look the picture closely, you may see 3 banks. Each bank has its own gate drive amplifier. Gate drive was placed as close to mosfets as possible. 
RC snubber was placed to eliminate ringing of gate drive.

3. IGBT vs. Mosfets
Good things about IGBT: They are not sensitive to voltage. You can get 600V or even 1200V IGBT with reasonable price. (One bad design habit from this: Designers don't care about high spikes or noise...They just use IGBT with higher voltage.)

Bad things about IGBT:
1). It's less preferred to parallel IGBT. Because IGBT has a diode drop inside. The hot one will take more current, and prone to be damaged.
2) It has high drop, usually > 2V, even to 3V. So 600A controller will have >1200W heat just for conduction. That's huge. That's why watercool etc is needed.
3) IGBT is slow on turn off, because of tail current. So the switching loss will be higher.

About MOSFET
1. Very sensitive to voltage. You have to manage to keep all possible spikes as low as possible. (Once you managed the spikes and noise to be good for mosfets, you could find you get good EMC performance as the side products)

2. You can parallel mosfets on theory and practice. Once a mosfets got hot for whatever reason, it got higher Ron, so the current will be lower. They are self balancing load among them.
Interestingly mosfet can take higher voltage once get hot. That's good for parallel also.

3. You can parallel more low Ron mosfets to get higher efficient. Lower Ron, more mosfets, less heat.
Kelly is putting more and more mosfets into controllers. KDHB has 21 pairs of mosfets! So you may get 0.3mohm (0.6mohm at hot) with 21 of 120V 7.5mohm mosfets! So you get 0.3V drop even at hot with 500A! That's about 1/10 of IGBT. With faster switching, Kelly KDHB 120V controllers are 5 to 10 times more efficient than products with IGBT technology! Or say, it only dissipates 1/5 to 1/10 of heat. 
Since the heat was so low, it can run with the high current very long. KDH12800B (800A) and KDH12100B (1000A) can beat controllers rated as 1400A and 2000A, and running cool.

Kelly is developing a new controller with 45 pairs of mosfets! The housing is not much bigger than KDHB. It should be able to do 120V 2000A and 144V 1500A. There are 3 layers of components inside (no way to service the controller. sorry about that...)

Also we will use the same housing to build 400V 1000A. We have to use IGBT for 400V controller though. Watercool is optional for the controller. obvioulsy it can dissipates a few kW of heat...So watercool is strongly suggested.

The same housing will be used for AC and BLDC controllers also, up to 120V 1000A, 144V 600A, and 400V 400A

Don't get impression it will be huge...It's only letter paper size, with 55mm thick. Tiny for the power.

We have many other products under development. Some will come soon. We just published 72V 600A and 120V 400A BLDC. Good to drive a car.

4. Isolation.

First of all, we have isolated power supply takes 8-30V, to accomodate car 12V or 24V battery. It will be in all high voltage controllers by default.

KDHA and KDHB have opto-isolation for gate drivers. In addition, it measure current and voltage with analog opto amplifier. It's kind of cost though. Those parts especially analog signal opto-isolation can be expensive. Manual adjusting may be needed to get precision. 

Kelly absorbed all those cost. No price increase for opto-isolated controllers.

Isn't it good: Kelly always improve products, and put more fundtions, without raise single penny! I appreciate many customer feedback and suggestions. We will keep improving and get better controllers for them. 

One project going is dual miroprocessors. Instead of isolate drivers and analog signals, we can isolate communication port between two microprocessors. It will reduce hardware cost and labor. The project have been going on for a couple months. Obviously firmware needs to be rewritten. We already had hardware running. That's long term platform of Kelly. 

Products under development:

A. KDC series. Similar to KD, but with higher current and more functions. Series motor regen is available.

B. Small BLDC. tiny housing to save space and cost

C. High voltage BLDC and AC motor controller

D. High power DC motor controller, up to 120V 2500A or 400V 1000A. PM 4Q, Series motor regen, sep-ex motor regen will come out one by one.

I guess now you may understood why Kelly came up with new products rapidly. We have at least 10 new type products under development. Every type covers whole range of current and voltage.

Lots of things to say...Keep an eye on Kelly website. 

To tell the truth, I seriously double the other guy can catch up with us. All Kelly is running efficiently. We can implement whatever we want now.

By the way, I am an engineer. I am happy to talk about technicals with people. 

Thank you,
Steven


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## Guest (Nov 2, 2008)

Actually the controller was not under rated as tested before being sold as a viable controller for the market. They decided to do that so you wont' push them beyond their limits. That decision was because of HOW folks were actually using the controllers. They also decided to do some upgrades and when they say it is rated for that you will know it is rated for that. They do honor the warranties. Yes mine was a special event but it was still a controller for sale. Just a couple minor modifications to the controller. Actually the special thing about the whole set up had more to do with the motor than the controller. The motor is a special motor and were used in the early days with contact switches for speed control and regen. We wanted to have a SepEx controller that would power one of these motors and still provide regen. Put a modern controller in charge of an older generation motor of special design. It works just fine. The controller is just fine and I have no issues with Kelly. None what so ever. The design is good. The design is great. 

Kelly has a design of controller that works but some of them did not perform as stated. That is something they have since fixed. It may not be perfect yet but without real world use no one will ever know. 

I too expect warranties to be honored and if they have a warranty that says 2 years then 2 years it is. I do not expect money back unless you have not used the item. If you have used the item then it's at least a replacement which Kelly has done. 

Actually many of Kelly controllers are doing just fine and only a few have actually died. If they are used as designed and not over taxed then they live. Over tax them in an environment then Poof. 

We are going to actually put one in a Race Buggy EV and push it to the limits. We want to help Kelly prove their product. That is how much I think they have a very good product and customer service. 

What I do not like is when someone takes a problem and bitches and tries to figure out a problem without first contacting the manufacturer of the product. They blast the quality and such and say nasty things because they are incompetent and don't have the decency to call the manufacturer to help. It is their money and if they manufacturer does not know of a problem a customer is having how the hell do you think they can fix the issue. Vicariously! Ha. If I were the manager I would want you to come to me and we can troubleshoot and if we get no where then we would replace it. But the customer needs to be honest with what they did. Many are not and actually ruined it because they did not read the instructions and that they thought they knew it all. As a business owner I have heard so many excuses as to why something broke. If I were at fault I would not expect to have it replaced by warranty. If it was the fault of the product then yes I'd expect a replacement.

As for my controller it was purchased as a working controller and not a prototype but they honored all warranty work. My fault or not. How many companies do that? Not to many.


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## Guest (Nov 2, 2008)

WOO HOO! Kudos to you all at Kelly Controller. 






StevenLi said:


> Thanks for sincere oppinion.
> First of all, personal attach came from personal attack...
> 
> 1. How to work at 120V.
> ...


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## JRP3 (Mar 7, 2008)

Steven, thank you for the informative reply. Much more effective than all your previous ones put together.


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## ZenDaddy (Jul 22, 2008)

Steven,

I am very glad to see you here in this forum. I believe that your presence here could be very valuable to our members and to your company.

There seems to be a great deal of negativity concerning Kelly controllers here and I would love to see that dispelled either by good information or perhaps corrected by the company utilizing constructive feedback from the members.

Members,

I would like to first say candidly that I am a solid fan of Kelly and of Steven. My experience with the company has been very good. It has not however been without pain! That pain was self inflicted. I will explain in a bit.

I am not an electrical engineer or even a qualified tech, my knowledge of circuits is rudimentary and for the most part self taught. I had a simple dc circuit class in high school (25 yrs ago!) that gave me a basic understanding that has been extremely valuable, however, I realize that I have forgotten more than I learned and that what I do remember is woefully insufficient to understand in depth exactly how a controller works and how to properly install and protect it without the assistance of folks who know what they are doing. Basically I know enough to be dangerous and am only protected by a solid knowledge of my weaknesses and a willingness to seek help.

My project _will_ be completely successful but only with a lot of trial and error.
There is NO simple, comprehensive, layman friendly instruction manual to follow. I (and I am sure many other backyard ev enthusiasts) have had to learn each step as I went, asking questions and begging assistance wherever I could find it.

I first decided to buy a Kelly 400 amp controller based on the price. The first issue I ran into was with the pot box. I had a curtis 5k box and the wiring diagram called for a 5v box. I called Kelly and Steven supplied me with a diagram that allowed me to use the 5k box by installing a 1k resistor in series on the 5v power supply to the box. It worked fine.

When I got the system installed and I road tested the truck for the first time I quickly concluded that it was underpowered. I called Steven at Kelly and he quickly gave me the option of an upgrade to a 600 amp with full credit towards the purchase. He sent me the controller before I sent him the exchange and did it quickly and with excellent customer service.

Everything was fine until just a few days ago. After I had announced to the world that the truck was done and I put it in the diyelectric car garage, I put the key in the ignition after taking the car off its charger and was shocked to have the motor instantly spin at max rpm, running away like a freight train off a cliff! Thank god I was in neutral. Thank god I had an emergency cutoff switch within easy reach.

I opened the hood and watched the smoke coming off the controller and the precharge resistor with shaking hands and a sinking feeling in the pit of the old gut.

Of course I instantly went to a mental place of blaming Kelly Controllers! I thought that I had installed it correctly and that I was blameless for the failure.

When I talked to Steven, I was angry and frustrated. He however was calm and concerned. He started asking me questions about how I had the system set up and before long he was able to tell me where _I_ screwed the pooch. When he told me how I had failed I was again (because of my lack of understanding and based on posts in this forum btw) suspicious. But for the purpose of that conversation I accepted his evaluation and moved forward.

He offered to take the controller back and send me a new one if I would share the charge. He basically needed to cover the cost of parts so I agreed to send back the fried controller and a check for $300. I did so and am waiting for the new controller as I write this

My gut needed me to verify that what he told me about my mistake was correct so I called my buddy Wistor at KTA. I explained the situation and we together came to the conclusion that Steven was exactly in line and was treating me _more_ than fairly.

I had wired the controller from the main battery pack in this order: battery pos – shunt – main contactor – main cutoff switch – controller positive. I had a 300 ohm precharge resistor across the contactor as per the Kelly wiring diagram. Unfortunately, I did not at that time completely understand _why_ that resistor needed to be there, so it only covered the contactor, not the _main cutoff switch_ which was between the contactor and controller.

There were many occasions while I was working on the truck where I would have the cutoff switch open while working and then go to test the truck, got in and turned on the key, realized that the switch was still open because nothing would happen, walk to the motor compartment and close the switch. LEAVING THE KEY ON!!!

SLAM!!!!! Voltage to the controller with no precharge……. Eventual catastrophic controller failure……….. My fault completely.

My fault completely, but Steven and Kelly are still backing me up.

Kelly naturally assumes that when you buy its product you know what you are doing. In this community of folks converting cars to ev’s, that is definitely not always the case.

There are only a few components involved in a basic ev and installing them correctly is not rocket science. It would be nice if there was a basic simple wiring diagram that anybody could understand without an electrical degree. A diagram that would have “Caution, don’t forget to-“warnings all over it that would make a layman know that they need more information or understanding. Sadly such a diagram does not exist (as far as I know).

I am _very_ happy with Stevens response to my situation. I do suggest to Kelly that since there is a growing market amongst layman ev’ers that a more comprehensive and simpler wiring diagram would save a lot of customer service hassle.

I hope that this long winded post will help at least one layman ev builder avoid the same mistake.

Thank you forum and Kelly

Michael


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## Guest (Nov 2, 2008)

That was a bold move but it helps explain to everyone. If only they had asked they would have already known. I knew because I asked and he explained the new stuff coming. 


Thanks Steven : )







JRP3 said:


> Steven, thank you for the informative reply. Much more effective than all your previous ones put together.


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## evcars (Mar 15, 2008)

For what its worth I love my Kelly 120 volt 800 amp. It will push my Honda Civic wagon better than the original ICE and I don't have a single complaint about this model's reliability. 

Steven and their customer service dept. have always been there to help me every time I had any questions. 

Before the new 800B, I in fact owned one of the older KDH12600 controllers and it did have problems that would cause it to shut down after long distances driving the Honda. 
They were more than willing to help make things right by getting me the new 120 volt 800B controller when it became available. 

Kelly is constantly improving their products and making controller options better for us EVer's. When I was researching which controller to use in my Honda, I was reluctant to use the Curtis because I had heard just as many horror stories about Curtis controllers failing or having problems.


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## StevenLi (Oct 30, 2008)

StevenLi said:


> Thanks for sincere oppinion.
> First of all, personal attach came from personal attack...
> 
> 1. How to work at 120V.
> ...


Sorry I forgot one thing.

Kelly controller does measure voltage drop (or say Ron) to get current information. It may need calibration of each controller though. By the way, Kelly have factory calibration program for almost every parameter, voltage, current, control parameter, etc.

The good thing about the method: It's lossless. A few mA it takes have been used to drive your motor
It measures motor current (or say mosfet current), so protects motor and mosfets.
Another good thing is the signal is relative high, 300mV instead of <10mV. So it's good for noise immunity.

It needs good sampling and holding circuit though. (Small thing like that can be challenging)

One common misunderstanding: The rating is for battery current. That's not Kelly is doing. Kelly measures motor current and rate controller with motor current. The controller can take much less current from battery, and output much more current to motor. Or say current multiplication. Isn't that good? 

Also Kelly power supply is a relative fancy one. It takes 8-30V, and output 12V for controller circuit usage. If the input voltage is <12V, it boosts voltage. If the input is >12V, it bucks voltage. All automatic. I have to see such small but fancy power supply is rarely seen on market.
We provide both isolated type and non-isolated type.

By the way, can somebody come up with tiny buck-boost power supply, or the sample-hold? I will consider the guy as serious competitor or coorperator...don't study Kelly design for the purpose though.


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## StevenLi (Oct 30, 2008)

gottdi said:


> Actually the controller was not under rated as tested before being sold as a viable controller for the market. They decided to do that so you wont' push them beyond their limits. That decision was because of HOW folks were actually using the controllers. They also decided to do some upgrades and when they say it is rated for that you will know it is rated for that. They do honor the warranties. Yes mine was a special event but it was still a controller for sale. Just a couple minor modifications to the controller. Actually the special thing about the whole set up had more to do with the motor than the controller. The motor is a special motor and were used in the early days with contact switches for speed control and regen. We wanted to have a SepEx controller that would power one of these motors and still provide regen. Put a modern controller in charge of an older generation motor of special design. It works just fine. The controller is just fine and I have no issues with Kelly. None what so ever. The design is good. The design is great.
> 
> Kelly has a design of controller that works but some of them did not perform as stated. That is something they have since fixed. It may not be perfect yet but without real world use no one will ever know.
> 
> ...


Really appreciate your feedback.
One reason Kelly is derating controllers because of new technology. Same as ceramic caps, mosfets doubles performance every two years. We used 15mohm 150V mosfets, which is the best available at the time. Now 150V 7.5mohm mosfets available. So why use the same mosfets for the current rating? Derate it a little bit will improve efficiency, and improve reliability.
Kelly 400A controller used to use 11mohm mosfets. Rigth now it uses 8moh. So you get better performance. Needless to say, we may rate controller with 11 mohm lower. 
Kelly keep coming up with higher and better controller. Keep searching the best components available. Meanwhile, we may derate controllers with existing components.
On the other hand, we claim it's 600A because we tested it with 600A. And it worked. But what if people drive it long time with full throttle? Derate will guarentee it will work well if you try to get max current all the time (It may drop current by itself.). Now all Kelly controllers are able to operate with full throttle all the time without shutdown.


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## Tesseract (Sep 27, 2008)

StevenLi said:


> ...
> Anyhow it comes to spikes on battery line. We put dozens 0805 caps that absorbes >10MHz noise, spreaded. We put dozens of 1210 ceramic caps to absorb noise >1MHz. We put many low impedance lytic caps to absorb <1MHz noise. Here just to give a rough idea of frequency range of capacitors. The line isn't that clear at real life though. But anyhow you have to max caps, with calculation or simulation how many you need.
> ...
> The good thing about using caps instead of other approach: >99.9% energy will be recovered.
> ...


Placing ceramic capacitors across the electrolytic reservoir capacitors is a good idea - for reducing noise and voltage pulsations in the battery cables, that is. This does nothing to protect the MOSFETs from the stray inductances present in the circuit. Furthermore, Coss (the capacitance in parallel with the drain and source) will form a very high-Q resonant network with the stray inductance between the two banks. If "struck" with the right pulse rise time this network will ring with up to several hundred volts of amplitude. Well, actually only somewhat more than 150V because the MOSFET will immediately avalanche. This heats up the MOSFET at the very least, and could result in its destruction if freewheeling current from the motor diverts into it.

Granted, if during prototyping you monitored the drain-source voltage with a 100MHz DSO in one-shot capture mode while applying pulses with different rise times to ensure there was enough "intrinsic damping" to suppress any ringing then all is good. 



> 2. Synchronize multiple mosfets
> It's difficult to drive more than 8 mosfets with single gate driver. The ringing and noise can be huge.
> Personally I don't think the delay is a big concern..electricity travel fast, should be in nano seconds range for 6 inches. The problem is ringing and noise.
> Kelly use segments. If you look the picture closely, you may see 3 banks. Each bank has its own gate drive amplifier. Gate drive was placed as close to mosfets as possible.
> RC snubber was placed to eliminate ringing of gate drive.


The problem with this approach is not so much how fast the pulses travel down the circuit board - that is irrelevant, as you noted - but with the unfortunate reality that different MOSFETs, even from the same batch, will have different transconductance curves, turn-on and turn-off delay times, etc. While it is true that the positive tempco of Rds[on] at significant currents does help to enforce current sharing when they are all on; the other issues, though, serve to prevent sharing during the time they are turning on or turning off. Inevitability, the fastest MOSFET will hog all the current at first; the slowest will be the last to turn off. In general, you either have to drive a parallel bank of MOSFETs more slowly or you have to hand match them for transconductance and speed. The latter is what is done with the IGBTs in the Zilla and that is one reason it is so robust.




> Bad things about IGBT:
> 1). It's less preferred to parallel IGBT. Because IGBT has a diode drop inside. The hot one will take more current, and prone to be damaged.
> 2) It has high drop, usually > 2V, even to 3V. So 600A controller will have >1200W heat just for conduction. That's huge. That's why watercool etc is needed.
> 3) IGBT is slow on turn off, because of tail current. So the switching loss will be higher.


Much as you noted above how ceramic capacitors have come a long way in the last few years, so it is with IGBTs. Let's just say that for a given voltage/current/speed capability they are more than competitive with MOSFETs.




> About MOSFET
> 1. Very sensitive to voltage. You have to manage to keep all possible spikes as low as possible. (Once you managed the spikes and noise to be good for mosfets, you could find you get good EMC performance as the side products)


Exactly why I took issue with using 150V MOSFETs in a controller with a label on it that says "Voltage: 24-120V". You cut it way too close in my opinion.




> 2. You can parallel mosfets on theory and practice. Once a mosfets got hot for whatever reason, it got higher Ron, so the current will be lower. They are self balancing load among them.
> Interestingly mosfet can take higher voltage once get hot. That's good for parallel also.


I agreet - during the on time the MOSFETs will share current very well. It is when turning on or turning off they don't share so well.




> 3. You can parallel more low Ron mosfets to get higher efficient. Lower Ron, more mosfets, less heat.


I have no issue with that - it's the main advantage to MOSFETs. You can achieve an arbitrarily low conduction loss. Of course, you have to balance that against the switching loss that comes from switching more and more MOSFETs on and off at the same time.




> To tell the truth, I seriously double the other guy can catch up with us. All Kelly is running efficiently. We can implement whatever we want now.


Who said anything about "catching up" with Kelly?


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## StevenLi (Oct 30, 2008)

ZenDaddy said:


> Steven,
> 
> I am very glad to see you here in this forum. I believe that your presence here could be very valuable to our members and to your company.
> 
> ...


Mike,
I really appreciate your frank feedback. I have seen many frank customer told me straight "I made mistakes" and willing to pay some. That's why I ship replacement before receive returns...Over 95% of customers returned the controller, in the good condition as possible, as promised. Sadly, a few do not return.

I like to claim something here: KDHA and KDHB have ZERO failure without misusing!

Meanwhile we are improving our products to withstand common errors. Actually every small signal inputs, rated as 5V usually, can survive short to 100V, or short to ground. It survives even you short 5V supply to ground. (Please note don't short high current terminals like PWR to GND. It will blow GND trace. No circuit to protect ground trace because no circuit there).

We are working on the issue the current surge caused by missing precharge resistor. We will get controller surviving the case. (You still need precharge resistor if you aware it. Missing precharge resistor can generate sparks and hurt the main contactor, as well as the controller).

Here is something I want to say to all prospective EV builders: Be patient. The project could be the biggest project many people ever worked on. And many people don't know much about electronics. Error can be made where you have never thought about. Let's work together to resolve issues. We always support every customer to successful application. That's our promising. We make mistakes. You too. Only very a few ways to make your EV work. While there are millions possibilities the EV doesn't work. 

Send your question, with pictures if possible, to [email protected]. We WILL response to your question.

Thanks,
Steven


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## Tesseract (Sep 27, 2008)

StevenLi said:


> By the way, can somebody come up with tiny buck-boost power supply, or the sample-hold? I will consider the guy as serious competitor or coorperator...don't study Kelly design for the purpose though.


The flyback and sepic topologies both handle the situation were the input voltage ranges below and above the desired output voltage just fine - there's nothing special about them.

Sample and hold design is all about a tradeoff between speed, noise immunity, and power consumption; pick any two.


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## 280z1975 (Oct 2, 2008)

Tesseract said:


> ... snip ...
> 
> Sample and hold design is all about a tradeoff between speed, noise immunity, and power consumption; pick any two.


I'm tired of all these three choices, pick two scenarios ... give me all three


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## StevenLi (Oct 30, 2008)

Tesseract said:


> The flyback and sepic topologies both handle the situation were the input voltage ranges below and above the desired output voltage just fine - there's nothing special about them.
> 
> Sample and hold design is all about a tradeoff between speed, noise immunity, and power consumption; pick any two.


That's not what I meant. No transformer here for non-isolated supply. That wastes money and space. You might waste money that can buy a few ATTiny


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## StevenLi (Oct 30, 2008)

280z1975 said:


> I'm tired of all these three choices, pick two scenarios ... give me all three


I have to say Kelly got all three.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Placing ceramic capacitors across the electrolytic reservoir capacitors is a good idea - for reducing noise and voltage pulsations in the battery cables, that is. This does nothing to protect the MOSFETs from the stray inductances present in the circuit. Furthermore, Coss (the capacitance in parallel with the drain and source) will form a very high-Q resonant network with the stray inductance between the two banks. If "struck" with the right pulse rise time this network will ring with up to several hundred volts of amplitude. Well, actually only somewhat more than 150V because the MOSFET will immediately avalanche. This heats up the MOSFET at the very least, and could result in its destruction if freewheeling current from the motor diverts into it.


Well, you talk about ringing here. We have ways to do it, and we did it. The ringing by switching is damping down rapidly.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Much as you noted above how ceramic capacitors have come a long way in the last few years, so it is with IGBTs. Let's just say that for a given voltage/current/speed capability they are more than competitive with MOSFETs.
> 
> Who said anything about "catching up" with Kelly?


Disagree. Can you find an IGBT beating 100V 4mohm mosfet in TO220? Give me data on power consumption and current capability.

The thing is: IGBT got to have >1.5V drop. That's too much for us. We managed drop <0.5V, mostly <0.3V. 

I don't know IGBT can be faster than mosfets. This is the first time I heard that. What's the tail current?

Great! Show us what you can do.


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## mattW (Sep 14, 2007)

I have to say that while this thread took a bit of a negative turn in the middle there it has become a really civil and interesting resource. This kind of discussion can only benefit the EV community as a whole.

My guess is that a lot of the problems with controllers come from a misunderstanding on the consumer's side of the way the controllers are rated and should be installed. It seems Kelly which I don't think originally was making the controllers for road vehicles took a while to adjust to the way consumers were using their products in new ways. I don't think the fact that they are improving their existing controllers should be a negative, even if the original controllers weren't up to scratch (I can't say either way) we should give them credit for improving their product.

There are ways both Kelly and its customers could have acted differently to make the past experiences more positive. The same could be said for this thread. There is no point in both sides just arguing "you haven't been perfect". Lets just focus on what is happening now which is positive and learn from past mistakes.


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## Hondacrzy (Mar 15, 2008)

Thanks to all on this thred for calming down a little. I think everyone can get more out of this now. I can understand everyones frustrations, but good feedback on both sides is what we need. The ultimate goal is to get more long lasting EV's on the road. I have not personaly talked with Steven L., But I tell you it sounds like you can at least get a timley responce back from him. I can't say the same with alot of other vendors here in the states. So please continue.

Ok I am getting off the soap box


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## david85 (Nov 12, 2007)

Yes, please continue.


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## vgslimo (Oct 21, 2008)

just want to say thank you to steven and i am back on my way to purchasing a kelly controller. this is really good info for entire community!


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## JRP3 (Mar 7, 2008)

One thing that can help both consumers and businesses is good documentation included with the controllers, or at least links to such. I don't know what Kelly provides but Alltrax has numerous down loadable wiring diagrams and schematics as well as documentation describing the proper contactors to use and the purpose and wiring of the precharge resistor and contactor diode.


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## Technologic (Jul 20, 2008)

StevenLi said:


> The thing is: IGBT got to have >1.5V drop. That's too much for us. We managed drop <0.5V, mostly <0.3V.
> 
> I don't know IGBT can be faster than mosfets. This is the first time I heard that. What's the tail current?


In audio amplifiers (which switching/noise is directly related to distortion) I've never ever seen IGBT's even thought of being used outside of high power low end applications (PA systems).

Mosfets are and will continue to be the standard for just the reason you are talking about here Steven.

I find his claims about IGBT's dubious at best considering my past experience. Compact low distortion (feedback), high switching capacity has always belonged to mosfets unless I'm tooooootally old school (ie. 2 years ago). I'm not certain about voltage drop, but as far as switching feedback levels mosfets react far better.


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## Technologic (Jul 20, 2008)

> 1). It's less preferred to parallel IGBT. Because IGBT has a diode drop inside. The hot one will take more current, and prone to be damaged.


This is precisely correct Steven.

His contention that IGBTs have advanced vastly over mosfets is totally baseless from where I am sitting. To my knowledge they are not even uping the ceramic tables into AlO, etc for diodes yet on any scale... I'd like to see IGBTs that can switch with lower feedback and higher thermal stability for even 1/10th the price of a 150v rated MOSFET.

And even if they could the rise in resistance you describe with heat in IGBT's is precisely why they don't use them in high power amplification.

It seems this guy's major issue with your controllers is in their rated amperage and voltage which, from my experience... should always be halved from manufacturer's specs anyway. They go by chip data 99% of the time when they rate anything (even the RAM in your computer). Amplifiers are the worse kind of lies in this way. Most amplifier companies quote peak ratings that the chip set could survive. And even the good companies rarely meet their specified ratings continuous.

The reason for this is the chinese manufacturers will often overspec everything... it's impossible to even design a circuit that can survive low ratings unless you bloat the specs completely, ie. buying 250v mosfets for a 120v circuit. Capacitors have the same issue. 

If this guy buys american IGBTs etc... you can guarantee his controller will be 8 times the price your's is offered... though, if it's on 2 ounce boards... maybe 10 times the price. Not bad for 5% added reliability at the top end?

In my opinion I'd rather just buy 2 steps above what I need and be done with it. Kelly will fix their ratings issues anyway I'm sure with their kind of warranty support.

I'd like to see a tenative controller schematic from this guy before I'm willing to hop on the "gravy train" of insulting someone's copper lead size amperage allow... which can be TOTALLY fixed with a fan let alone just a piece of 2 dollar aluminum heatsink (if you're REALLY going to start pumping 600amp in a controller rated for a max 600amp rating).

I seriously don't understand why EVers are pulling that much amperage and hoping it will be "cheap" on the controller, or why not water cooling the chips isn't a must if you're going to start throwing 600amp draws from a dead stop through a controller. That's a lot of damn amperage... You'd be hard pressed to find a single audio amplifier that can safely draw that much (at any price point... even in the $9000 dollar range)


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## Technologic (Jul 20, 2008)

Last post on this matter:

600amp draws through a controller section would effectively be driving a car in 5th gear, from a dead stop, with roughly 2500 lbs of weight. And this can be totally avoided with a simple relay system added pre-controller if someone was this foolish.

However, there is a corvette running on lithium right now with a kelly controller that has no transmission at all. And only pulls 350A from a dead stop (2800 lbs) max. 

the 40C heat build up tass talks about is nothing inside of a high output circuit... anything less than 80C is normal operating temps for most mosfets... aluminum sinks + 1 fan could effectively reduce the temp build up by 60% or more depending on sink size.


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## Tesseract (Sep 27, 2008)

First off, I have remained civil and tried hard to not insult anyone or any product, for that matter. I have even pointed aspects of this controller that were good (e.g. - the electrolytic capacitors chosen are high quality from United-Chemicon). That said, _*this thread is about a KDH12600 that died an early death.*_ Please respect the thread topic and skip the personal attacks (that means you, Technologic, gottdi and, most definitely, StevenLi). I have not personally attacked anyone and I expect the same in return. If you can not write something of substance with a neutral tone then do as your parents ought to have taught you and _don't write anything at all._ 

Secondly, ask yourself what I stand to gain from starting this thread? Have I revealed the name of the company that contracted me? No. Have I made any sort of promotional comments along the lines of "My controller will be better than [x] controller because..."? No. When I do produce a working controller I will let people know in the appropriate vendors forum here and will maintain a presence here for people to comment, gripe, whatever.




Technologic said:


> In audio amplifiers (which switching/noise is directly related to distortion) I've never ever seen IGBT's even thought of being used outside of high power low end applications (PA systems).
> 
> Mosfets are and will continue to be the standard for just the reason you are talking about here Steven.
> 
> I find his claims about IGBT's dubious at best considering my past experience. Compact low distortion (feedback), high switching capacity has always belonged to mosfets unless I'm tooooootally old school (ie. 2 years ago). I'm not certain about voltage drop, but as far as switching feedback levels mosfets react far better.


What works in a linear amplifier is totally irrelevant to hard-switched applications like motor drives, switchmode power supplies, etc. Even so, bipolar transistors (BJTs) still reign supreme over any other semiconductor device when it comes to linear amplification.. (cf.: Douglas Self, Nelson Pass).

At any rate, IGBTs achieve a much higher current density than MOSFETs for a given voltage rating. They are slower than MOSFETs, true, but the 16kHz or so switching frequency most commonly used in VFDs, dc motor controllers, etc., is hardly high-speed for even second generation IGBTs, much less the 4th and 5th gen. products out now. You are approximately 15 years out date, not 2.



Technologic said:


> His contention that IGBTs have advanced vastly over mosfets is totally baseless from where I am sitting. To my knowledge they are not even uping the ceramic tables into AlO, etc for diodes yet on any scale... I'd like to see IGBTs that can switch with lower feedback and higher thermal stability for even 1/10th the price of a 150v rated MOSFET.


It's hard to find an IGBT rated for so low a voltage, but how about this one for an example: Fairchild part number FGH40N60UFD is a "Field Stop" IGBT that costs around $2US in quantities of 100 and has the following specs:

Ic = 40A @ 100C
Vce[sat] = 1.8V @ 40A (equiv. to an Rds[on] of 0.045 ohms)
Qg = 120nC @ 400V
Positive TC of Vce[sat] at all current levels

Note that last comment - the on drop of this type of IGBT rises with temperature much like the beloved MOSFET, making it easier to parallel (still have to address getting them all to switch on and off at the same time, but that's a problem with any semiconductor - diode, bjt, MOSFET, IGBT, SCR, GTO, etc...).

Oddly enough, this part costs much less than _any_ MOSFET rated for a similar current at 150V, much less the 400V the Fairchild part can withstand.




Technologic said:


> It seems this guy's major issue with your controllers is in their rated amperage and voltage which, from my experience... should always be halved from manufacturer's specs anyway. They go by chip data 99% of the time when they rate anything (even the RAM in your computer). Amplifiers are the worse kind of lies in this way. Most amplifier companies quote peak ratings that the chip set could survive. And even the good companies rarely meet their specified ratings continuous.


No, my major problem is that this controller blew up when operated at 96V while programmed to limit the peak current to 150A; in other words, at 80% of its claimed voltage and 25% of its claimed current. 

Once again, we are not discussing an amplifier, though I do agree most manufacturers of such tend to vastly over-state peak power ratings.




Technologic said:


> I'd like to see a tenative controller schematic from this guy before I'm willing to hop on the "gravy train" of insulting someone's copper lead size amperage allow... which can be TOTALLY fixed with a fan let alone just a piece of 2 dollar aluminum heatsink (if you're REALLY going to start pumping 600amp in a controller rated for a max 600amp rating).


Hey, I was born at night, sure, but not _last night_. Why in the world would anyone intending to produce something commercially post the schematic for it??? I didn't ask StevenLi to post the schematic for the KDH12600, I took it upon myself to do some casual reverse-engineering of it. If you want the schematic to any product I design you can buy one and spend the time yourself reverse-engineering it.



Technologic said:


> 600amp draws through a controller section would effectively be driving a car in 5th gear, from a dead stop, with roughly 2500 lbs of weight. And this can be totally avoided with a simple relay system added pre-controller if someone was this foolish.


Not correct: the locked-rotor current of even a 6.7" motor such the ES-31B is around 2000A, so a larger motor such as ADC's 9", Warp's 9, 10, etc., will draw even more if allowed to when starting from a dead stop. The higher the current rating of the controller the faster the EV will be able to *accelerate*, assuming the controller can limit the PWM output to prevent exceeding even the short-term current limit of the circuit.

Frankly, Technologic, you haven't made a single correct statement related to motor controllers or IGBTs in your 3 posts here and then compounded this gaffe by attacking me. Are you a shill for Kelly?


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## Technologic (Jul 20, 2008)

Tesseract said:


> Not correct: the locked-rotor current of even a 6.7" motor such the ES-31B is around 2000A, so a larger motor such as ADC's 9", Warp's 9, 10, etc., will draw even more if allowed to when starting from a dead stop. The higher the current rating of the controller the faster the EV will be able to *accelerate*, assuming the controller can limit the PWM output to prevent exceeding even the short-term current limit of the circuit.
> 
> Frankly, Technologic, you haven't made a single correct statement related to motor controllers or IGBTs in your 3 posts here and then compounded this gaffe by attacking me. Are you a shill for Kelly?


Actually I've never used their controllers... though I still find your claims about IGBT's switching capabilities far from well supported... maybe you can provide links to current motor controllers using them instead of mosfets?

2000A is asinine as I'm sure you realize... if you're drawing that much you'll have far larger long term issues (like destroying entire packs of lithium).

Most commerical lithium systems, and any custom style system like the aptera... makes use of no transmission yet has a max draw (before the batteries fry permanently) of around 300amps-400amps. Batteries don't dump power the way you suppose... maybe you were using this one farrrrrr beyond it's current capacity.


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## fugdabug (Jul 14, 2008)

Technologic said:


> Actually I've never used their controllers... though I still find your claims about IGBT's switching capabilities far from well supported... maybe you can provide links to current motor controllers using them instead of mosfets?
> 
> 2000A is asinine as I'm sure you realize... if you're drawing that much you'll have far larger long term issues (like destroying entire packs of lithium).
> 
> Most commerical lithium systems, and any custom style system like the aptera... makes use of no transmission yet has a max draw (before the batteries fry permanently) of around 300amps-400amps. Batteries don't dump power the way you suppose... maybe you were using this one farrrrrr beyond it's current capacity.


Uh, I may be wrong 'technologic' but I think this may be in relation to lead-acid batteries and not lithium packs...(?)
Also, if you know any specifics of the Aptera could you start a thread (or have you somewhere on the forum?) on that subject? Inquiring minds want to know more...


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## Tesseract (Sep 27, 2008)

Technologic said:


> Actually I've never used their controllers... though I still find your claims about IGBT's switching capabilities far from well supported... maybe you can provide links to current motor controllers using them instead of mosfets?


I'm not making the claims, Fairchild, Infineon/Semikron, APT, and IXYS are. notice how I did not included Powerex, the most well-known power IGBT module manufacturer - their products are woefully behind the times.

As for a current motor controller that uses IGBTs? The Tesla does; AC Propulsion; Metric Mind; and, on the DC side, Zilla (sadly out of production for the time being - a damn fine controller from what I've seen, though).



Technologic said:


> 2000A is asinine as I'm sure you realize... if you're drawing that much you'll have far larger long term issues (like destroying entire packs of lithium).


No argument, with this, but I didn't say you should allow motor to draw that much current, just that a motor *can* draw that much current _if the controller (and battery pack) let's it!_ Thus, a 200A controller OUGHT to allow a motor to draw 200A when starting from a dead stop (giving feeble acceleration) while a 600A controller ought to safely allow the motor to draw 600A (note that because the effective voltage across the motor is so low - i.e., the PWM on-time will be limited to much less than 100% - the actual current drawn from the battery pack will be much less than the motor current. I_batt_ = I_motor_ / D)




Technologic said:


> ... Batteries don't dump power the way you suppose... maybe you were using this one farrrrrr beyond it's current capacity.


I supposed nothing about batteries - only about what a series wound DC motor would do when starting from a dead stop.


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## Guest (Nov 4, 2008)

If any of your products come to market and become a big hit and someone decided to take it upon themselves so casually to reverse engineer it and then decide to take some of that and produce a better product and you became aware of it after I highly doubt you'd be a happy camper with that.



> If you want the schematic to any product I design you can buy one and spend the time yourself reverse-engineering it.


No but you just decided to take it upon your self and reverse engineer it and that is usually done to TAKE the good (steal) and put it into your own product you were hired to build. With that we can say any thing we please. In our eyes or at least mine it's down right THEFT. I am sure the owner of Kelly is none to happy about it either. But then again it is the way of the world. But I still don't accept it. 

Just go build your own and boast about how good it is. If it is good then you can boast. If not you'd fix it to make it better then you can boast again. : ) 

We are not Shills for KELLY. We just happen to like the product and support honest business practices. Like honoring warranties and fixing problems and informing the company that there is a problem that needs fixing. 



> Please respect the thread topic and skip the personal attacks (that means you, Technologic, gottdi and, most definitely, StevenLi).





Tesseract said:


> First off, I have remained civil and tried hard to not insult anyone or any product, for that matter. I have even pointed aspects of this controller that were good (e.g. - the electrolytic capacitors chosen are high quality from United-Chemicon). That said, _*this thread is about a KDH12600 that died an early death.*_ Please respect the thread topic and skip the personal attacks (that means you, Technologic, gottdi and, most definitely, StevenLi). I have not personally attacked anyone and I expect the same in return. If you can not write something of substance with a neutral tone then do as your parents ought to have taught you and _don't write anything at all._
> 
> Secondly, ask yourself what I stand to gain from starting this thread? Have I revealed the name of the company that contracted me? No. Have I made any sort of promotional comments along the lines of "My controller will be better than [x] controller because..."? No. When I do produce a working controller I will let people know in the appropriate vendors forum here and will maintain a presence here for people to comment, gripe, whatever.
> 
> ...


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## JRP3 (Mar 7, 2008)

Taking something apart to see how it works is neither illegal nor morally wrong in any way. If someone takes apart a failed engine made by GM and then points out what is wrong with it and tries to improve upon it is that wrong? Of course not, and thousands of people have made businesses doing just that.
Tesseract has calmly and rationally discussed what he's seen, expressed his opinions, and provided facts to back them up. I don't care if Steven is not happy that his controller was taken apart and analyzed, that's exactly what should happen with a device that fails, that's how we all learn and how things improve. The best end result from this is that Kelly may make improvements to their controllers and produce a better product, (and it sounds as if they are already doing so), and that Tesseract will make a better controller as well. There is plenty of room for quality controllers in the EV world and competition is good for everyone.
If you build something you better expect to have it dissected.


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## Technologic (Jul 20, 2008)

Tesseract said:


> As for a current motor controller that uses IGBTs? The Tesla does; AC Propulsion; Metric Mind; and, on the DC side, Zilla (sadly out of production for the time being - a damn fine controller from what I've seen, though).
> 
> 
> .


Well naming off AC controllers doesn't provide me with much insight WHY they are using IGBTs in DC controllers?

AC propulsion (which is the Tesla btw) is also the most overpriced/expensive car motor made currently, forgive me for not jumping up and down in excitement at finding out a 109,000 dollar car uses IGBTs in its AC controller.



> Thus, a 200A controller OUGHT to allow a motor to draw 200A when starting from a dead stop (giving feeble acceleration) while a 600A controller ought to safely allow the motor to draw 600A (note that because the effective voltage across the motor is so low - i.e., the PWM on-time will be limited to much less than 100% - the actual current drawn from the battery pack will be much less than the motor current. I_batt_ = I_motor_ / D)


I don't disagree and I'm right there with you wanting a snubber diode in motor controllers simply because I see no reason NOT to have one. The problem I stated of knowing the real continuous abilities of any chinese components is indeed accurate. Your desire to overengineer things is virtuous in my opinion, though possibly misguided commerically. I don't know if it truly is commercially viable to have the kind of "over the top" engineering of components in motor controllers.

Granted I, personally, would love to see someone making something at kelly prices that have all of the electronic features and 2oz copper boards (though to be honest the lack of snubbers really does bother me)... but I honestly don't know that any company would WANT to try to make those things for kelly prices.

And if you come along and have this overengineered (though likely better) version of the kelly controller at 2 times the price... it won't sell. Maybe you can cut costs somewhere... but I'm not sure if you can or not. I know populated circuit boards are only getting cheaper though.


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## Qer (May 7, 2008)

JRP3 said:


> Tesseract has calmly and rationally discussed what he's seen, expressed his opinions, and provided facts to back them up. I don't care if Steven is not happy that his controller was taken apart and analyzed, that's exactly what should happen with a device that fails, that's how we all learn and how things improve. The best end result from this is that Kelly may make improvements to their controllers and produce a better product, (and it sounds as if they are already doing so), and that Tesseract will make a better controller as well. There is plenty of room for quality controllers in the EV world and competition is good for everyone.


Indeed. Also, it's not like Tesseract has dissected the controller, stolen the design and is now planning to do a clone out of it to avoid the development cost. On the contrary, the decision to use IGBT's instead of MOSFET's means that almost nothing of the Kelly design can be reused and the parts that CAN be reused is pretty common and well-known facts.

With other words; I agree with that the tone has been pretty pissy against Tesseract. He's done the community a favor by explaining why this controller failed, the weak spots in the design and how it can be improved. This is facts that are good feedback for Kelly, and good to know for the community, and the only reason to bitch back is if you know that you're doing a sub-standard product and don't want anyone to find out. So personally I don't understand the response. If he wanted to just clone the controller and make some easy bucks it'd be pretty stupid of him to let anyone know about it.

Also; the origin of the Zilla controller was that Otmar didn't like the (then) quality of Curtis so he reverse-engineered it, decided he could do something better and thus, eventually, the Zilla was born. You can read about it here: 

http://cafeelectric.com/curtis/

So, gentlemen, mind your manners. We WANT to share information for the common good of EV's, if you agree with that it's a very bad behavior to shoot the messenger.

Just my $0.02.


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## Technologic (Jul 20, 2008)

fugdabug said:


> Uh, I may be wrong 'technologic' but I think this may be in relation to lead-acid batteries and not lithium packs...(?)
> Also, if you know any specifics of the Aptera could you start a thread (or have you somewhere on the forum?) on that subject? Inquiring minds want to know more...


Well I suspected it was lead acid batteries, but it's still a mind boggling amount of amperage.

I don't really know any specifics outside of the motor size, voltage, pack size of the Aptera (10kwh) for a 120 mile range... belt fixed gear transmission. It also has a Cd of 0.11

Sorry I can't be of more assistance mate.


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## Technologic (Jul 20, 2008)

Qer said:


> So, gentlemen, mind your manners. We WANT to share information for the common good of EV's, if you agree with that it's a very bad behavior to shoot the messenger.
> 
> Just my $0.02.


I truly don't see any problems with reverse engineering anything either just so long as it's not to directly steal (which many times is done overseas to avoid infringements).

I don't know enough about electrical engineering to provide any specifics if IGBTs could work for the same price point or not. My experience is totally in class A solid state amplification, and very DIY (teaching myself in my spare time in undergrad).

I hope he's right about IGBTs and it makes me want to engage in some more learning about how you'd go about a controller using these. Might have to get some more design books and see what I can come up with. 

I, truly, understand the guy's frustration with companies using 1oz boards though.... it's a problem in high current amplification as well. Real 2oz boards are freaking impossible to find in China, at least it took me awhile to find manufacturer's of them.


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## Qer (May 7, 2008)

Technologic said:


> I don't know enough about electrical engineering to provide any specifics if IGBTs could work for the same price point or not. My experience is totally in class A solid state amplification, and very DIY (teaching myself in my spare time in undergrad).


Well, from my experience it's a totally different field with very different requirement. Class A amplifiers for example dissipates LOADS of heat since you're trying to track a specific amplitude while in a perfect world PWM'ing doesn't generate any heat at all since the transistor is either on or off. In reality you get losses, of course, but they're not even close to the losses in a class A amplifier.

Also, since a class A amplifier has very moderate slopes you don't have the same problems with overshots etc. In PWM-situations it's common that you get a lot of nasty spikes and stuff that you have to handle one way or another. There's one of the big advantages with IGBT's as far as I've understood it; many IGBT's can handle 300 Volts or more, so an IGBT can usually handle spike that would kill a MOSFET. The advantage for MOSFET's are, as is already pointed out, less losses at saturation. Win some, lose some.

In the end it's an engineering problem, not a customer problem. Frankly I don't care if the controller uses rodents in hamster wheels as long as it's reliable! It should be AT LEAST as reliable as an ICE, preferably better. If that takes a huge heat sink that's fine with me as long as I get to work and back every day.


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## Technologic (Jul 20, 2008)

Qer said:


> In the end it's an engineering problem, not a customer problem. Frankly I don't care if the controller uses rodents in hamster wheels as long as it's reliable! It should be AT LEAST as reliable as an ICE, preferably better. If that takes a huge heat sink that's fine with me as long as I get to work and back every day.


Seemingly so... which is what perplexed me so much about the attacks... heatsinks are FAR cheaper than 2oz boards and total redesigns.

And amplifiers, especially class A, have to dissipate 600w of heat for every 200w or so, making heatsink areas huge.

I'd much rather sink and fan up a kelly controller (or hell liquid cool it) then pay twice as much for a zilla.


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## Qer (May 7, 2008)

Technologic said:


> I'd much rather sink and fan up a kelly controller (or hell liquid cool it) then pay twice as much for a zilla.


The Zilla was extremely expensive since it was a lot of manual labor involved. The construction demanded that the IGBT's were perfectly matched and that work was very time-consuming which of course resulted in a higher price. The IGBT's themselves were probably not the problem so I think it's safe to claim that an IGBT-based controller doesn't necessarily has to cost as a Zilla.


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## JRP3 (Mar 7, 2008)

Technologic said:


> Well naming off AC controllers doesn't provide me with much insight WHY they are using IGBTs in DC controllers?


 He did provide the example of the Zilla for a DC usage.


> AC propulsion (which is the Tesla btw) is also the most overpriced/expensive car motor made currently, forgive me for not jumping up and down in excitement at finding out a 109,000 dollar car uses IGBTs in its AC controller.


The AC motor/controller combo costs around $25k and is probably the best in the business at this time as far as power to weight ratio. That doesn't come cheap.



> And if you come along and have this overengineered (though likely better) version of the kelly controller at 2 times the price... it won't sell. Maybe you can cut costs somewhere... but I'm not sure if you can or not. I know populated circuit boards are only getting cheaper though.


Remember, the Zilla, even the 2kamp version at $4500.00 and a 6 month wait time, sold out. So a well designed high amperage controller will sell.


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## Technologic (Jul 20, 2008)

JRP3 said:


> He did provide the example of the Zilla for a DC usage.
> 
> The AC motor/controller combo costs around $25k and is probably the best in the business at this time as far as power to weight ratio. That doesn't come cheap.
> 
> ...


Selling out is almost meaningless... selling 100,000 pieces in a year... isn't. If he was making them one at a time and giving you a 6 month lead... selling out could easily mean "making 3 controllers a year".

It's all about volume... and I know kelly is doing a lot more market share than Zilla ever did. I'm not suggesting that a high end controller isn't worth it... but I CERTAINLY won't pay over 1 grand for a controller ever.... I'd rather tinker for mths and build my own (to my own specs) for that price.

And based upon components mentioned that Tass found in the kelly... it probably cost closer to 90 dollars FOB... if not less. I remember pricing out 1000 part runs for amp boards (extremely expensive, 100,000F cap class As) that ran less than 75 bucks/each to a boat for 2oz 2 layer boards. That was before copper rose though so it might be different. And large snubber diodes in china are 20 cents... 

You really shouldn't be using www.digikey.com prices for components when thinking about what a board would cost.


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## david85 (Nov 12, 2007)

I'm not completely sure if the tesla is using AC propulsion proprietary technology, but I agree that AC propulsion's system is one of the most overpriced systems ever made.


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## JRP3 (Mar 7, 2008)

There are 92 Zilla controlled EV's in the evalbum, which makes it the third most popular controller after Alltrax and Curtis. 
No it's not 100,000 units a year, but neither is Alltrax or Curtis. Considering the relatively small market for home built DC conversions no one will be selling thousands of dc controllers a year for a while, if ever.


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## JRP3 (Mar 7, 2008)

david85 said:


> I'm not completely sure if the tesla is using AC propulsion proprietary technology, but I agree that AC propulsion's system is one of the most overpriced systems ever made.


Is there another motor available with the same power to weight ratio at any price? Also, the price includes the motor, controller, charger, and DC/DC power supply.
Price out the most powerful motor and controller from metric mind, then add in the high voltage charger and DC/DC inverter. Yes it's expensive but I don't know of anything that is it's equal for less.


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## Technologic (Jul 20, 2008)

JRP3 said:


> There are 92 Zilla controlled EV's in the evalbum, which makes it the third most popular controller after Alltrax and Curtis.
> No it's not 100,000 units a year, but neither is Alltrax or Curtis. Considering the relatively small market for home built DC conversions no one will be selling thousands of dc controllers a year for a while, if ever.


Well Alltrax and Curtis both are used in other industries... ie. forklifts and the like.


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## JRP3 (Mar 7, 2008)

True, and probably why they don't really make high powered units. Alltrax tops out at 72 volts as far as I know, Curtis around 144 or so.


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## frodus (Apr 12, 2008)

JRP3 said:


> True, and probably why they don't really make high powered units. Alltrax tops out at 72 volts as far as I know, Curtis around 144 or so.


A month or so back, I checked on Curtis' website and noticed that the 144V model was not on their products list. They're still being sold, but I'm unsure what to think about that. 120V is still there though.


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## StevenLi (Oct 30, 2008)

Tesseract said:


> The company that hired me to design them a controller was motivated to do so because they too have had poor experiences with the infamous Wen/Steven Li.
> .


About personal attack: How did you read above words?


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## StevenLi (Oct 30, 2008)

JRP3 said:


> Frankly your attitude isn't helping Kelly very much either. Comparing Kelly controllers to crap like Vista isn't a great selling point. Millions of people won't touch Vista because it's not ready for use. I'd like you to show me a single thread where someone took a 72 volt Kelly controller and hooked it up to 90 volts as you claim, especially since that's an unusual voltage for ev's.


On the other hand, I will say billions people used or will use Vista.


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## Technologic (Jul 20, 2008)

StevenLi said:


> About personal attack: How did you read above words?



lol... precisely. *shrugs*


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Also, so far as I know, no one has ever received a refund for a bad controller - only a replacement or an offer to "upgrade for the difference in price". This applies to Li's distributors, too, so they eventually get stuck with the loss. Of course, that will eventually decrease their willingness to carry Kelly products - who wants to sell crap that when it breaks you have to eat the cost yourself?
> 
> .


The tone is calm! But all by assumptions, not facts. Which distributor stuck on loss? Please point it out.

Calm..how can I evaluate above claims? I have to say "straight face lie".


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## Technologic (Jul 20, 2008)

StevenLi said:


> The tone is calm! But all by assumptions, not facts. Which distributor stuck on loss? Please point it out.
> 
> Calm..how can evaluation above claims? I have to say "straight face lie".


lol... I may be the only DIYer that likes your style steven, but I do nonetheless


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## StevenLi (Oct 30, 2008)

Tesseract said:


> One other thing about the KDH12600 controller that I didn't even notice is that even the bus bars are woefully undersized for the current! For a 600A max rated controller the bus bar needs to be at least 1/4" x 1" (that's technically 400A continuous with a 30C temp rise... from just the bus bar conducting current! At 600A the temp rise will be 50C; acceptable but not ideal). The KDH12600 bus bars are only 0.110" x 0.625" - good for about 150A).


I have to point out, almost all mosfets manufacturers rated mosfet pin, less than 1x1mm, to 80A or 100A.
According to this, how much 3x16mm copper bar would be rated?


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## StevenLi (Oct 30, 2008)

Tesseract said:


> Doubly-unfortunately, the 150V Vds rating of the FDP2532's pretty much dooms them to failure if the motor leads are more than a couple feet long and/or the battery pack voltage is more than 96V. And if that wasn't tempting fate enough, there does not appear to be any sort of snubber to suppress spikes from stray inductance.
> 
> Continued...


The only thing I would say is that many people used KDH12600B and KDH12800B with 120V batteries, >130V fully charged, without failure. Same FDP2532 is used.
Double unfortunately, the conclusion isn't true again.


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## Guest (Nov 5, 2008)

My biggest bitch and gripe with the whole idea of taking apart the controller and then proceeding to slam the maker is that he was not willing to discuss with Kelly what could be improved. That indicates that he has intentions to use Kelly engineering and then add some of his own stuff for the person or persons who contracted him to design a controller. It is pretty easy to add two and two and come up with four on this one. I had even asked if he had talked with Kelly about it and if not he should. But he said that would be a conflict of interest. Why? He has his own design, RIGHT! If I were the one who hired I would be wary of this practice. Usually the practice of tearing things apart and reverse engineering them is to use some of the said engineering designs of someone else so you don't have to go through all the bull your self. It is also done outside American boundaries to avoid legal issues and to be able to steal a design with out having to pay the original maker. That is immoral and is actually illegal. Just because he is only talking and says what he says he had no intention to let Kelly know what he found and what may make it actually work. I have no problem with folks who are up front and honest about what they do and to help when help needed. If his intentions were to inform Kelly of the findings and maybe give some friendly advice then I would never have had a problem with this whole affair. But Noooooooooooo. He had to say he would not. But now that Steven is in the picture the tune has changed. That was the intention of getting him involved in the first place. He had that right that you were not willing to give him. Now the cats out of the bag so to speak. I know he will be a bit more careful in what and how he conducts his business and what he actually says here on the forum. It is a tight legal rope he is walking. I also known that Kelly will be careful and they will look at their own products a bit more careful. In the end we all will prosper and we will all learn lessons and we will have a decent product on the market. Maybe even a few good products form a few different companies competing for that market. I am game for that. But if you do have something you can contribute and you want paid then maybe you can either start your own or go to work for someone who needs your expertise. But don't use someone else's stuff as your one or incorporate it into your own products without giving due compensation. Give Kelly that due compensation. If you have your own superior design then helping another is not in conflict. 

Pete : )

This is in response to a few of you on this list. 





JRP3 said:


> Taking something apart to see how it works is neither illegal nor morally wrong in any way. If someone takes apart a failed engine made by GM and then points out what is wrong with it and tries to improve upon it is that wrong? Of course not, and thousands of people have made businesses doing just that.
> Tesseract has calmly and rationally discussed what he's seen, expressed his opinions, and provided facts to back them up. I don't care if Steven is not happy that his controller was taken apart and analyzed, that's exactly what should happen with a device that fails, that's how we all learn and how things improve. The best end result from this is that Kelly may make improvements to their controllers and produce a better product, (and it sounds as if they are already doing so), and that Tesseract will make a better controller as well. There is plenty of room for quality controllers in the EV world and competition is good for everyone.
> If you build something you better expect to have it dissected.


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## Tesseract (Sep 27, 2008)

StevenLi said:


> The only thing I would say is that many people used KDH12600B and KDH12800B with 120V batteries, >130V fully charged, without failure. Same FDP2532 is used.
> Double unfortunately, the conclusion isn't true again.


Ok, so how did just one MOSFET out of 24 blow as shown in the first post in this thread? It certainly wasn't from someone connecting the battery pack backwards or failing to pre-charge the bus...




> I have to point out, almost all mosfets manufacturers rated mosfet pin, less than 1x1mm, to 80A or 100A.
> According to this, how much 3x16mm copper bar would be rated?


The pins on the TO-220 package are limited to 50A peak (ie - for a short duration). Pretty much any datasheet warns you of that.

The current rating for a bus bar is directly proportional to how much of a temperature rise you are willing to tolerate (within reason). The spec I gave you was for the amount of current that would raise the bus bar temperature 30C rise over ambient and it came directly from a bus bar manufacturer. A 3x16mm bus bar at 400A would rise 50-60C over ambient... The temperature rise is due to I^2R losses, and while R is very low, I^2 is very large. At 400A a bus bar with a mere 1 milliohm of resistance will still dissipate 160W of heat. _That's_ how come your 3x16mm bus bars don't meet the current rating. But the bus bars are a mere nuisance compared to the foil on the pc board connecting the MOSFET sources and the input reservoir capacitors.

Look, Steven, companies *pay me* to provide the sort of analysis I've given you for free. Why not use it to make a better product which will lead to better profits, btw, rather than waste time making an a$$ out of yourself on this forum?


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## Guest (Nov 5, 2008)

Actually I have been helping a kid who was going to put in some extra batteries because he said the limits were higher than that 72 volts and being that the limit was 90 then he could add those. I told him that he can't without burning up his controller. Actually my attitude is what got this heated stuff started because your friendly decided to tear apart a dead kelly controller with no intention of doing anything but provoking and bashing Kelly and with the intent to harm Kelly company. Claiming it would be conflict of interest. How absurd. Like I said if he has a superior design then helping his fellow would not be in conflict. Too bad too many folks decide to not help but complain. 

Did I compare Kelly to Vista? 

Just to recap. Yes 90 volts is an odd size but if someone is stupid enough to add enough extra because it is the max then they deserve to smoke the controller. Sadly there are plenty of folks who would do just that.





JRP3 said:


> Frankly your attitude isn't helping Kelly very much either. Comparing Kelly controllers to crap like Vista isn't a great selling point. Millions of people won't touch Vista because it's not ready for use. I'd like you to show me a single thread where someone took a 72 volt Kelly controller and hooked it up to 90 volts as you claim, especially since that's an unusual voltage for ev's.


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## david85 (Nov 12, 2007)

Tesseract has shared a lot of information here. I think if his intention was to reverse engineer the kelly controller, he would have been more discrete about it an not posted anything here.

I had high hopes for kelly because of the more advanced options and far better price compared to the curtis controller, but so far I'm still not ready to trust the product.

I am still hoping that this thread can resolve some of the concerns that I as well as others have. *Now if only we could get the discussion to be a little more mature and stay on topic.....*


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## Technologic (Jul 20, 2008)

Tesseract said:


> Ok, so how did just one MOSFET out of 24 blow as shown in the first post in this thread? It certainly wasn't from someone connecting the battery pack backwards or failing to pre-charge the bus...



lol there's numerous ways... amperage spike, using a higher voltage than is commonly used... a higher amperage etc.


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## JRP3 (Mar 7, 2008)

gottdi said:


> My biggest bitch and gripe with the whole idea of taking apart the controller and then proceeding to slam the maker is that he was not willing to discuss with Kelly what could be improved.


I'm sorry but that is just BS. He's pointed out possible weaknesses and suggested some possible changes, how much more is he supposed to do for Kelly? As he stated, he gets paid by others to figure this stuff out and give them the information they've paid for, and here he's given some to all of us, including Kelly, for free.
He easily could have kept quiet and not posted anything at all, which would have helped no one but himself. I'm quite glad he's sharing his knowledge, and I'm just as glad to hear Steven make his points. The discussion is valuable to all of us.


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## JRP3 (Mar 7, 2008)

> Did I compare Kelly to Vista?





gottdi said:


> What about VISTA. What a disaster that was and the expense of the customer. Same with thousands of other products. Products are not perfect at first and problems do arise and if the company is wanting a market share they will take care of the problem.


Since Microsoft offers free patches to fix it's operating systems I guess it's all good? And no one should try to figure out what is wrong with it and tell other people?


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## StevenLi (Oct 30, 2008)

gottdi said:


> My biggest bitch and gripe with the whole idea of taking apart the controller and then proceeding to slam the maker is that he was not willing to discuss with Kelly what could be improved. That indicates that he has intentions to use Kelly engineering and then add some of his own stuff for the person or persons who contracted him to design a controller. It is pretty easy to add two and two and come up with four on this one. I had even asked if he had talked with Kelly about it and if not he should. But he said that would be a conflict of interest. Why? He has his own design, RIGHT! If I were the one who hired I would be wary of this practice. Usually the practice of tearing things apart and reverse engineering them is to use some of the said engineering designs of someone else so you don't have to go through all the bull your self. It is also done outside American boundaries to avoid legal issues and to be able to steal a design with out having to pay the original maker. That is immoral and is actually illegal. Just because he is only talking and says what he says he had no intention to let Kelly know what he found and what may make it actually work. I have no problem with folks who are up front and honest about what they do and to help when help needed. If his intentions were to inform Kelly of the findings and maybe give some friendly advice then I would never have had a problem with this whole affair. But Noooooooooooo. He had to say he would not. But now that Steven is in the picture the tune has changed. That was the intention of getting him involved in the first place. He had that right that you were not willing to give him. Now the cats out of the bag so to speak. I know he will be a bit more careful in what and how he conducts his business and what he actually says here on the forum. It is a tight legal rope he is walking. I also known that Kelly will be careful and they will look at their own products a bit more careful. In the end we all will prosper and we will all learn lessons and we will have a decent product on the market. Maybe even a few good products form a few different companies competing for that market. I am game for that. But if you do have something you can contribute and you want paid then maybe you can either start your own or go to work for someone who needs your expertise. But don't use someone else's stuff as your one or incorporate it into your own products without giving due compensation. Give Kelly that due compensation. If you have your own superior design then helping another is not in conflict.
> 
> Pete : )
> 
> This is in response to a few of you on this list.


Pete, that's the point. If you open a controller purely from a customer point view, it's one story. If you are hired to build a controller, and open other company's controller, that's another story. (Tell me, what's the reason to do it? To pointout something objectively? How can that be true if you are hired with purpose?) 

I announce here: Kelly has never opened other's controller! That's why Kelly controller has such unique structure, good or bad. 

Steven


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## JRP3 (Mar 7, 2008)

StevenLi said:


> I announce here: Kelly has never opened other's controller! That's why Kelly controller has such unique structure, good or bad.
> 
> Steven


That just seems foolish. Before I build anything I try to see what has been done before so I can copy what is good and improve on what is bad, that is the way products evolve and improve. The phrase "why reinvent the wheel" is appropriate.


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## StevenLi (Oct 30, 2008)

JRP3 said:


> I'm sorry but that is just BS. He's pointed out possible weaknesses and suggested some possible changes, how much more is he supposed to do for Kelly? As he stated, he gets paid by others to figure this stuff out and give them the information they've paid for, and here he's given some to all of us, including Kelly, for free.
> He easily could have kept quiet and not posted anything at all, which would have helped no one but himself. I'm quite glad he's sharing his knowledge, and I'm just as glad to hear Steven make his points. The discussion is valuable to all of us.


If you are hired to build controller, yes, please keep it quiet if you opened other's controller as the minimum. Just give info to his paid for. Kelly don't need it.
By the way, I really didn't see informing Kelly was one of his purposes. Did you see it? And Kelly don't appreciate that info neither. (How much all those false info worth?)
Don't share other people's product if you are a would-be compititor (Certainly I can imagine he is at far-higher level so really no compitition).
You can share your design if you like. I am waiting for that.


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## JRP3 (Mar 7, 2008)

Luckily he is a free individual and is allowed to say whatever he wishes, whether you agree with him or not, just as you are allowed to respond. Once again I'll say it, if you build something you should expect someone else to take it apart, and if you built it well you should not be upset at what is found inside.


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## JRP3 (Mar 7, 2008)

StevenLi said:


> You can share your design if you like. I am waiting for that.


I would suggest you do what he did, buy the product and take it apart yourself. You did not give him a free controller to take apart, why should he do that for you?


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## StevenLi (Oct 30, 2008)

JRP3 said:


> Since Microsoft offers free patches to fix it's operating systems I guess it's all good? And no one should try to figure out what is wrong with it and tell other people?


I was just pointed out a fact. Fact is fact.
Believe in imagination and ignore facts are kind of problems.


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## StevenLi (Oct 30, 2008)

JRP3 said:


> That just seems foolish. Before I build anything I try to see what has been done before so I can copy what is good and improve on what is bad, that is the way products evolve and improve. The phrase "why reinvent the wheel" is appropriate.


You can buy wheel.


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## ngrimm (Oct 19, 2007)

I'm neither pro or con concerning Kelly. All I know is if I choose a less expensive option, (Kelly) I need to accept the risk. But I don't see anything wrong with tearing one apart to figure out why it failed. Heck if Otmar hadn't done the same thing with Curis there wouldn't be a Zilla controller. I don't know of any patents on Kelly's design nor am I aware of any new technology they are using that anyone could or would steal. All that was given was Tesseract's opinions as to why it failed and possible suggestions as to what could be done with the design to possibly prevent future failures. So who is harmed? Just my opinion.


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## JRP3 (Mar 7, 2008)

StevenLi said:


> You can buy wheel.


I think my analogy was lost to the language barrier. My point was by looking at a previous version of what you want to build you can avoid making mistakes that have been made before.


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## StevenLi (Oct 30, 2008)

JRP3 said:


> Luckily he is a free individual and is allowed to say whatever he wishes, whether you agree with him or not, just as you are allowed to respond. Once again I'll say it, if you build something you should expect someone else to take it apart, and if you built it well you should not be upset at what is found inside.


I don't want to repeat, but have to: "It's one story if you are from pure customer pointview".


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## JRP3 (Mar 7, 2008)

ngrimm said:


> I'm neither pro or con concerning Kelly. All I know is if I choose a less expensive option, (Kelly) I need to accept the risk. But I don't see anything wrong with tearing one apart to figure out why it failed. Heck if Otmar hadn't done the same thing with Curis there wouldn't be a Zilla controller. I don't know of any patents on Kelly's design nor am I aware of any new technology they are using that anyone could or would steal. All that was given was Tesseract's opinions as to why it failed and possible suggestions as to what could be done with the design to possibly prevent future failures. So who is harmed? Just my opinion.


Exactly right.


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## StevenLi (Oct 30, 2008)

ngrimm said:


> I'm neither pro or con concerning Kelly. All I know is if I choose a less expensive option, (Kelly) I need to accept the risk. But I don't see anything wrong with tearing one apart to figure out why it failed. Heck if Otmar hadn't done the same thing with Curis there wouldn't be a Zilla controller. I don't know of any patents on Kelly's design nor am I aware of any new technology they are using that anyone could or would steal. All that was given was Tesseract's opinions as to why it failed and possible suggestions as to what could be done with the design to possibly prevent future failures. So who is harmed? Just my opinion.


We do appreciate sincere feedback from customer, or independent analyser. That's how Kelly improve products.
But that's not his purpose.
The nice intent was suggested, and was refused.


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## StevenLi (Oct 30, 2008)

JRP3 said:


> I think my analogy was lost to the language barrier. My point was by looking at a previous version of what you want to build you can avoid making mistakes that have been made before.


My past 10 year experience: If people want to understand me, they do. If they don't, they don't. There are lots more barriers than language, including standards and views. (Language barrier here again. Sorry about that. I guess nopoint to debate between us...)


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## JRP3 (Mar 7, 2008)

StevenLi said:


> I don't want to repeat, but have to: "It's one story if you are from pure customer pointview".


No it's not. Anyone, even a competitor, can take apart your product and analyze it and discuss what is found. There is nothing wrong with that and nothing you can do about it.


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## Guest (Nov 5, 2008)

Anyone can do any thing they want at any time when ever and where ever but that does not make it morally acceptable. Honesty does not require a patent. Good tidings do not require a patent. 

The nice intent was suggested, and was refused. When it was refused to discuss with the manufacturer about the pitfalls of a product then the intent was not to be helpful but to do harm and to take. I took that away by involving Kelly Controller. Now every one is pissed and that alone shows that I was correct to do such. 

Have a nice day : )

Just because you can does not mean you should! 



JRP3 said:


> No it's not. Anyone, even a competitor, can take apart your product and analyze it and discuss what is found. There is nothing wrong with that and nothing you can do about it.


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## Guest (Nov 5, 2008)

The intentions were not possible suggestions as to what could be done to prevent further failures. Kelly was harmed. The intentions were to not say a damn thing to kelly because it conflicted with him making a controller for a customer. What friggin bunk. If he truly had his own superior design then he never would have needed to dig this apart and openly state he would not talk to Kelly about his findings because of the so called conflict. After Steven Li was involved the tone changed. 



ngrimm said:


> I'm neither pro or con concerning Kelly. All I know is if I choose a less expensive option, (Kelly) I need to accept the risk. But I don't see anything wrong with tearing one apart to figure out why it failed. Heck if Otmar hadn't done the same thing with Curis there wouldn't be a Zilla controller. I don't know of any patents on Kelly's design nor am I aware of any new technology they are using that anyone could or would steal. All that was given was Tesseract's opinions as to why it failed and possible suggestions as to what could be done with the design to possibly prevent future failures. So who is harmed? Just my opinion.


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## ngrimm (Oct 19, 2007)

This whole argument is a total hijack of the original topic and I view that as immoral.  That said, I believe he has no obligation to help Kelly or anyone else. He hasn't tried to sell us anything either. Personally, I don't like it when people use DIY sites like this to promote their products for financial gain but I'm not the moral police. I have my own selfish reasons for visiting this site. Many of us are building our own controllers anyway and appreciate Tesserect's or anyone else' technical information regarding the design of such. I might not agree with every single thing he says but so what. These are just my opinions and you don't have to agree with them.


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## Qer (May 7, 2008)

gottdi said:


> The nice intent was suggested, and was refused. When it was refused to discuss with the manufacturer about the pitfalls of a product then the intent was not to be helpful but to do harm and to take.


You know, that's probably the most oversimplified reasoning I've heard today. Admittedly, it's still morning and I haven't even finished my first cup of coffee, but it's still very oversimplified.

In my experience most manufacturers aren't really interested in feedback unless you have a very strong point to make. To convince a manufacturer that you're right and they're wrong usually takes a lot of arguing and thus a lot of time since the general opinion from a manufacturers view is that the product is "good enough" and it's costly to introduce changes. It's also so that if you get maybe ten suggestions, at least nine of them are pure crap and not worth the time it takes to read them.

What makes StevenLi interested in this specific case is, I'd say, the fact that the information is now made public. It doesn't really matter if the information is 100% accurate or real bollocks, it's public and thus can hurt the reputation and, secondary, sales. I sincerely doubt Tesseract could've got his point through this easy if he'd reported back to Kelly directly instead of posting to this forum.

How I know this? I'm in the manufacturer end as well, although in a different market segment. If we'd listen to all the cr... I mean, feedback we got from our customers we wouldn't be doing anything else. 

With that said, I think your conclusion that "Doesn't wanna report back -> just intend harm" is oversimplified, close to naive.

This thread is just getting more and more stupid for every post (probably including this one).


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## Tesseract (Sep 27, 2008)

Folks - My intention in this thread was not to bash Kelly nor was it to promote my own product. I was given the controller to take apart only to see why it failed, not to duplicate it or expose trade secrets to the public, etc. That said, it really doesn't matter what the intent behind my actions was, what matters is how other people interpreted those actions. 

I've been using the internet since 1990 so I really ought to know better that forums (and the USENET newsgroups that pre-date them) are often a "Wild West" of opinion and that writing about another manufacturer's product when I, myself, am a potential competitor to that manufacturer is just asking for trouble. Which is to say, I should've seen this coming.

So, I apologize to all the forum members, but especially to gottdi, Technologic and StevenLi, whom I seem to have offended in particular. While I maintain my stance that I meant no harm with this thread, I am also acknowledging that those who have been harsh on me here have just as valid a stance, despite my disagreement.

Engineers are often sterotyped for their lack of social skills and I guess this thread proves I'm guilty of that.

Once again, sorry for causing offense; please accept that I did not intend to do such.

***

I also want to add the following:

1. I believe there is more than enough room in the controller market for several companies to thrive. 

2. Kelly does appear to be making a significant effort to improve their products. Maybe they weren't perfect at first but at least they are making the effort to improve them, and making their controllers more reliable benefits not only them but the EV community in general - the lower the failure rate of *all* controllers the more confidence people will have about EVs in the first place.

3. I also did not mean to characterize the KDH12600 as a total disaster - some aspects of its design are excellent and well optimized but I perhaps did not emphasize those aspects as much as did those I felt were negative. For example, it was especially smart of them to employ a whole bank of MOSFETs as synchronous freewheeling diodes because this greatly lowers conduction losses at the expense of only a small increase in switching losses. This is a big advantage for MOSFETs over IGBTs because IGBTs only conduct in one direction so turning them on in parallel with the freewheeling diode does absolutely zilch.

4. Finally, I now realize after going through this entire thread that I implied a very unreasonable expectation upon Kelly, and all other controller manufacturer's by extension, that no product for this application should ever fail. Of course they will fail - they have the job of trying to tame 50kW worth of power with perhaps a business card's worth of silicon. At this power level, sometimes things just go "poof".


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## JRP3 (Mar 7, 2008)

Tesseract I see little reason for you to apologize, but it's good of you to do so anyway. Except for a vocal minority, (Steven, gottdi, and technologic), the rest of us appreciate what you have done and can see quite clearly that you had no evil ulterior motive. Probably because we are only seeking information and do not have any emotional connection to the product being discussed. Please continue to analyze and post any findings you have for those of us who do not have the skill or knowledge to do so ourselves.


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## Qer (May 7, 2008)

JRP3 said:


> Probably because we are only seeking information and do not have any emotional connection to the product being discussed. Please continue to analyze and post any findings you have for those of us who do not have the skill or knowledge to do so ourselves.


I concur. This thread, and the spin-off about building your own controller, has taught me a LOT about the pitfalls of trying to PWM inductive load. I now realize that my knowledge I had before probably was suited to PWM light bulbs but not much beyond that, if I ever try to build some kind of serious voltage controller now I have a much higher probability to actually succeed in the task too.

Knowledge is good. The more knowledge the EV-community collects, the better for the future of DIY-EV's and Internet is a great place for sharing knowledge. There's absolutely nothing to apologize for imo.


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## Guest (Nov 5, 2008)

Cool, Apology accepted. Thanks for this letter. Never thought you were out to reveal trade secrets to the public but only to your benefit. Now I see you really did not feel that way. Thanks.

Pete : )






Qer said:


> You know, that's probably the most oversimplified reasoning I've heard today. Admittedly, it's still morning and I haven't even finished my first cup of coffee, but it's still very oversimplified.
> 
> In my experience most manufacturers aren't really interested in feedback unless you have a very strong point to make. To convince a manufacturer that you're right and they're wrong usually takes a lot of arguing and thus a lot of time since the general opinion from a manufacturers view is that the product is "good enough" and it's costly to introduce changes. It's also so that if you get maybe ten suggestions, at least nine of them are pure crap and not worth the time it takes to read them.
> 
> ...


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## CPLTECH (Sep 14, 2007)

Tesseract is like many of us that want to take stuff apart and see what makes them tick. I can relate to that. If manufacturers really tried to keep you from examining their product, they would use such tactics as proprietary chips that no one has any idea what is inside them (and some do) or potting the board with epoxy to hide all the parts below (try to chisel that stuff off).
Our company (like many others) would buy a competitors product to see if they could improve it in their one small area of expertise and then try to sell them on its improvements made. Often worked. Problem is that we were over taken by advancing and changing technology…


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## Technologic (Jul 20, 2008)

JRP3 said:


> Tesseract I see little reason for you to apologize, but it's good of you to do so anyway. Except for a vocal minority, (Steven, gottdi, and technologic), the rest of us appreciate what you have done and can see quite clearly that you had no evil ulterior motive.


No, I don't disapprove of what he did... just how he did it.

I don't think MOSFET controllers, 1oz boards, etc etc are worthy of denouncing a motor controller when it's the standard practice with the exception of specific application made units.


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## madmike (Jul 11, 2008)

I've been reading this thread, and frankly have learned a lot from it. I was sad to see it turn into what seemed to be personal attacks. I'm glad that to see that part end, but hope the engineering part continues. I'm a hobbyist, I'm building a controller. I'm probably doomed to fail a bunch of times, but I enjoy the challenge and the learning. I hope to learn more from all of you along the way...

Thanks...


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## vgslimo (Oct 21, 2008)

madmike said:


> I've been reading this thread, and frankly have learned a lot from it. I was sad to see it turn into what seemed to be personal attacks. I'm glad that to see that part end, but hope the engineering part continues. I'm a hobbyist, I'm building a controller. I'm probably doomed to fail a bunch of times, but I enjoy the challenge and the learning. I hope to learn more from all of you along the way...
> 
> Thanks...


i agree completly


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## Guest (Nov 6, 2008)

In the end good information came from all this and to that end I now move on to my EV and my Kelly upgrade. I will keep you updated as I move forward with a new high power Kelly for my Ghia. I will be upgrading to 144 volts and may need to go to 8 volt batteries to keep the weight down. : )


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## Tesseract (Sep 27, 2008)

Technologic said:


> No, I don't disapprove of what he did... just how he did it.


Fair enough - I didn't think I was going about it poorly, and the poll seems to support that, but the poll results aren't unanimous, either. 




Technologic said:


> I don't think MOSFET controllers, 1oz boards, etc etc are worthy of denouncing a motor controller when it's the standard practice with the exception of specific application made units.


I have to set the record straight on this one, though. I did not denounce MOSFETs or 1oz boards, rather, I only pointed out that it is very difficult to parallel a bunch of MOSFETs (much less IGBTs) together and switch them simultaneously and that a 2oz copper board would need to be approx. 5.4" wide to carry 600A of current with a modest temperature rise. 

Furthermore, it is definitely not standard practice to use 1oz boards and banks of MOSFETs in industrial ac motor drives (VFDs). Maybe the unbelievably cheap ones you can get from Automation Direct (which are surprisingly reliable in my experience - go figure) use 1oz Cu plating, but none of the manufacturers of these drives - literally, none - uses banks of MOSFETs (or IGBTs).

Now, I gathered from what stuff you've said earlier in this thread that you are an audiophile and that you have some experience with pure Class A output stages. You know, then, that they are monstrously inefficent, maxing out at 25% if the collector or drain load is a constant current source or 12.5% if the load is a resistor. To get any decent amount of wattage out of a Class A circuit you need to parallel output devices, but my understanding is that the emitter/source degeneration needed to get them to share current nicely and the negative feedback needed to get them to swing their collectors/drains at the same time is sometimes too high a price to pay for the added output current.

Anyway, paralleling the output devices does not inevitably lead to doom, it just increases the chances of it happening. The circuit designer has to make a tough decision: do the benefits of using a single module versus a bunch of smaller devices outweigh the costs? Sometimes, yes; sometimes, no. I only pointed out that all manufacturers of VFDs, so far as I know, have chosen using single modules. 

Another consideration: if you are only selling a couple hundred of these things a year (e.g. - Cafe Electric sold an estimated 180 Zilla's one year, going by what Otmar reported in his production log) then it probably does not make economic sense to use modules - you aren't buying enough of them to get a good price, whereas if each controller uses 24 MOSFETs then you will be buying them in enough quantity to warrant a decent discount, even if you only sell a 100 controllers a year.

Finally, I was remiss to also not point out that it is *far* easier to make a "gold-plated" gadget - that is, use the best of everything and derate stuff into the dirt so it is virtually indestructible - than it is to make an economically sensible one! What really illustrates good engineering, to me, anyway, is when a product is optimized to deliver the best performance for the lowest cost.


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## Technologic (Jul 20, 2008)

Tesseract said:


> Now, I gathered from what stuff you've said earlier in this thread that you are an audiophile and that you have some experience with pure Class A output stages. You know, then, that they are monstrously inefficent, maxing out at 25% if the collector or drain load is a constant current source or 12.5% if the load is a resistor. To get any decent amount of wattage out of a Class A circuit you need to parallel output devices, but my understanding is that the emitter/source degeneration needed to get them to share current nicely and the negative feedback needed to get them to swing their collectors/drains at the same time is sometimes too high a price to pay for the added output current.
> 
> Anyway, paralleling the output devices does not inevitably lead to doom, it just increases the chances of it happening. The circuit designer has to make a tough decision: do the benefits of using a single module versus a bunch of smaller devices outweigh the costs? Sometimes, yes; sometimes, no. I only pointed out that all manufacturers of VFDs, so far as I know, have chosen using single modules.


paralleled output devices is basically the standard of audiophilia (at least home audio). I've never seen anything but headphone amps (small 5w class A's) that didn't have 12-24 output devices in parallel per channel.

At least in the instances of Class A's I often (very often) see larger (200w per channel) amplifiers running 32+ output devices in parralel... the reason for this is heat dissipation and lower distortion of the signal due to heat etc.

I don't think a single module has any benefits besides some inductance stablization over multiple output devices.

At any rate MOST amplifers (besides class A which use many kinds of output pods) use mosfets in parallel.


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## Tesseract (Sep 27, 2008)

Technologic said:


> ...I've never seen anything but headphone amps (small 5w class A's) that didn't have 12-24 output devices in parallel per channel...


Leaving your dubious claim about 12-24 output devices in parallel being the norm, not the exception aside... _5w into headphones, eh?_ Hmmm... virtually every pair of headphones made will produce around 90-100dB of sound pressure ("SPL") with just one stinkin' milliwatt of input power. As you probably well know, it does take 10x more power to merely double the apparent volume (e.g. - go from 90dB to 100dB) but even if we assume the average sensititivity is 90dB @ 1mW it would still only take 1W to hit 120dB, or the threshold of pain. 5x more power, or 5w, would get you to 126.7dB, or thereabouts, which I daresay only an already deaf-person would likely tolerate for any length of time... 

Now, you might say I have some experience with this since one of the products I currently make is a well-regarded headphone amplifier for use by motorcyclists... It puts out 100mW while staying under 0.1% THD and no one, I mean no one, thinks it needs more power...


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## Voltswagen (Nov 13, 2008)

I have read this entire thread and only wish I had participated earlier.
I'm not an engineer - I'm just an old Wrench Guy who wanted to build one Electric before retiring.
I own a Kelly KDH12600B installed in a Super Beetle with a 120v system and purchased the controller directly from Kelly.
I have only driven the car approx 60 miles since completion and I would say I have punished it. My intention is to break in the batteries and motor brushes so I drive it like an ordinary car. Firm acceleration to 50mph...lots of stop and go. I try to drain the batteries to 70% DOD every time I take the car out.
Each time I arrive home, I open the Motor (formally engine) Cabinet and put my hand on the D&D Motor....its hot....to hot to keep your hand on it
but the Kelly......cool to the touch *AND* ....(Steven will not want to hear this) I even disconnected one of the two cooling fans on the heat sinks to save the juice.
Fully charged at 133v the Kelly seems not to mind.
During my build I had the occasion to speak with Steven at Kelly numerous times. He understood that I was an electrical novice and took the time to explain and help me work out any difficulties I was having.
I'm confident that if my controller fails within the warranty period, Steven will replace it for me.
While 60 miles is not exactly "test track" proven, I'm thus far comfortable with my purchase from Kelly.
Roy Mann - Freehold NJ


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## motor_builder (Dec 25, 2008)

If the source has a significant amount of resistance, as in a battery, capacitor rms current at 50% pwm will be roughly 50% of motor current. In this case, 50% of motor current is 300 amps. The caps are rated 1.4 amps at 105 C, assuming a 5 C temeprature rise. For a more modest internal controller temperature of 60C the caps will be rated 4.2 amps. 10 caps will give a continuous current rating of 2 x 42 amps or 84 amps. This is probably why most of the internal volume of controllers like Curtis or Sevcon is filled with capacitors.


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## david85 (Nov 12, 2007)

Welcome to the forum, motor_builder. Are you actually an EV motor builder?


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## motor_builder (Dec 25, 2008)

Thank you. I mostly design motors and controllers, but occasionally build a prototype or 2. My last reply was slightly in error. The 10 KHz rating of the 330 uF, 200VDC KXG capacitor is 2.93 A at 105 C, I assumed the value provided in this post is correct but the United Chemicon data shows a multiplier of 2.05 for 10 KHz operation. The value given in this posting is the 120 Hz current rating. At 60 C, the rating is 8.79 A so the continuous rating for a bank of 10 capacitors is 10 x 2 x 8.79 = 176 amps. At 40 C, it's 211 A, at 25 C, it's 234 A. It's possible that the capacitor ratings have improved since the last tables were published and the capacitors are capable of handling 260 amps continuous, the continuous rating of the controller.

The initial reaction is that the capacitors are relatively small but it looks like Steven Li found some good capacitors and saved a lot of space.


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## david85 (Nov 12, 2007)

Do you have a website or some other company info?


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## Tesseract (Sep 27, 2008)

motor_builder said:


> ...The 10 KHz rating of the 330 uF, 200VDC KXG capacitor is 2.93 A at 105 C, I assumed the value provided in this post is correct but the United Chemicon data shows a multiplier of 2.05 for 10 KHz operation. The value given in this posting is the 120 Hz current rating. At 60 C, the rating is 8.79 A...


http://www.chemi-con.com/files/KXG0703.pdf

The 120Hz rating for a 330uF cap in this series is 1.43A and the multiplier for 10kHz/105C is 1.75 so it can withstand 2.50A of ripple. The life is excellent for an electrolytic - 10,000 hours at 105C with rated ripple - so using the temp multiplier as well isn't the bad idea it usually is. After all, 10,000 hours of EV run time is around 300,000+ miles. Hence, why I said the capacitors were a good choice, all things considered 

There isn't a temp multiplier in that datasheet (or I missed it) - where did you find it? _(or are you extrapolating the multiplier by assuming a 10C difference from core to ambient?)_


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## Wirecutter (Jul 26, 2007)

Well, I'm still reading the thread, but it's kinda long and I've skipped a bit of the "flaming" to save time.

Aside from the "flaming", I find this thread very informative. Tesseract, StevenLi, and a others here have made some great contributions. Once cooler heads prevail, the forum reverted nicely back to what the forum is supposed to be in the first place: exchange of information. A former coworker of mine once said that he enjoyed engineering because it dealt more with facts and less with opinions. In simpler terms, it works or it doesn't.

Look, controllers will fail. It's pretty hard to anticipate _everything_ a design might face. We all know, despite our attempts to make something _foolproof_, that fools are pretty ingenious. So is Murphy.

I'd like to suggest that others regard this thread and this forum as I do: a source of information. It's a chance to do what I once saw in someone's forum signature - "learn from the mistakes of others, because you won't live long enough to make all those mistakes yourself."

-Mark


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## Bowser330 (Jun 15, 2008)

well said...


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## motor_builder (Dec 25, 2008)

Tesseract said:


> http://www.chemi-con.com/files/KXG0703.pdf
> 
> The 120Hz rating for a 330uF cap in this series is 1.43A and the multiplier for 10kHz/105C is 1.75 so it can withstand 2.50A of ripple. The life is excellent for an electrolytic - 10,000 hours at 105C with rated ripple - so using the temp multiplier as well isn't the bad idea it usually is. After all, 10,000 hours of EV run time is around 300,000+ miles. Hence, why I said the capacitors were a good choice, all things considered
> 
> There isn't a temp multiplier in that datasheet (or I missed it) - where did you find it? _(or are you extrapolating the multiplier by assuming a 10C difference from core to ambient?)_


A complete catalog with a thermal rating section is available at the chemi-con website. The table thermal ratings are based on a 5C drop at 105C. Ratings at other temperatures are based on I/Io=sqrt(110-T/5).


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## motor_builder (Dec 25, 2008)

david85 said:


> Do you have a website or some other company info?


Thanks for asking. There's no website or company info. I work for companies I've come in to contact with while working on projects for other companies. It's all by referral.


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## david85 (Nov 12, 2007)

motor_builder said:


> Thanks for asking. There's no website or company info. I work for companies I've come in to contact with while working on projects for other companies. It's all by referral.


I sent you a private message.


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