# DIY AC motor controller super size part 1



## Technologic (Jul 20, 2008)

Well I started another thread cause we were nearing 30 pages... and my raw schematic is "vaguely" close to stress testing and part sheets.

I'm not particularly happy with it, for lots of reasons. Though the component choices are excellent (if I do say so myself) it's not cheaply priced enough.

http://img406.imageshack.us/img406/7552/part1e.png

Who would have thought the $17 MCK201 DSP would look cheap at this point? well the gate driver and other components all tallied up are close to $80 in ICs.

I want to drop this to about 1/4th that for the parts minus IGBTs... and the only way I can see doing that is going to a position only sensor V/Hz model... 

I must say that the MCK201 is amazing though... it allows for simple motor input parameters (ie. max RPM, inductance etc) and compensates the programming... even allowing for different PWM freq for different motors... Full on vector control without worrying about modifications.

The registry can be updated from any computer with a simple excel sheet they give you through the serial port... really nifty stuff.

The torque command is giving me issues... I'm trying to figure out how to do the throttle on it currently (Hall sensors will be coming in soon but those are simple)

The optoisolators on the current sensors are inverting... I'm sure this will be a problem since the 22771 isn't inverting 

They don't give you enough parameters for this stuff... I've been contacting IRF about the 22771 and they keep giving me incorrect answers.

At any rate I forsee setting this aside once I get a solid design and starting in on a simplified (very reasonable 100-200 dollar finished) V/Hz AC controller, since this would be much faster.

This design, however, has been a good learning experience... the IGBTs for it really should be like 1800v x 800A ones if you want to use the full 1200v and 600A it's designed around so far.

Output stage will be on a separate board and in a separate case if you value your motor 

Cheers... input always welcome
Just be gentle if at all possible 

Edit: I dropped the optoisolators from the current sensors... after rereading I noticed the input for PO (IB1 and IB0) don't need a higher voltage.


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## etischer (Jun 16, 2008)

Couldn't you just put your current transducer in backwards (current flow in opposite direction) to compensate for your inverting circuit?

Why are you worried about $80 in ICs? Most EV inverters are priced around $4k.


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## Greenflight (Sep 13, 2007)

What did you have in mind for a source for the MCK201? I wasn't coming up with extremely credible sources on my google searches... Sounds like a nice IC though!

I've been playing around a little with the Freescale MC3PHAC. It's pretty much useless for anything but industrial motors running V/Hz, but it's good for educational purposes.


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## Technologic (Jul 20, 2008)

Greenflight said:


> What did you have in mind for a source for the MCK201? I wasn't coming up with extremely credible sources on my google searches... Sounds like a nice IC though!


It's beyond nice.

I can grab samples of it from IRF, the problem is people DIYing with it (building these one at a time) is out the question.

I found sources to get them in 100s...which is fine for a DIY controller (ie. sell them with PCBs etc).



> Couldn't you just put your current transducer in backwards (current flow in opposite direction) to compensate for your inverting circuit?
> 
> Why are you worried about $80 in ICs? Most EV inverters are priced around $4k.


I'm worried about it considering how pricey the components are (IGBTs) and I still need a contactor for the main DC current... it's all just rather expensive when you are shoving 1800v x 800A IGBTs in as well .

This controller would really need to be preassembled to make it viable for DIYers, which is fine, I just don't want to shove capital into such a project 

The vector control isn't practical in my opinion, and it's also clear that most commerical AC controllers (ie. curtis and zapi) probably aren't using it.

And no, that won't work for the inverting optocoupler... it's not really a good idea to have it anyway... the PO output is being pulled up to 5v which is too high for most optocoupler inputs in the first place.

If you judge "practical pricing" by 3 times the component costs ... this controller should cost (roughly) twice-three times as much as a DC controller that can handle the same current range/voltage.... which would put it at $8000... totally unacceptable in my opinion.


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## etischer (Jun 16, 2008)

Technologic said:


> The vector control isn't practical in my opinion, and it's also clear that most commerical AC controllers (ie. curtis and zapi) probably aren't using it.


Why wouldn't it be practical? With V/hz all you can do is control speed, with vector control you can control torque. Plus you get much more low speed torque.

IF you're trying to save $60, why not buy smaller IGBTs? 800 Amps is insane, what kinda motor are you running?


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## Greenflight (Sep 13, 2007)

Have you looked at the double, triple, and hex pack IGBT modules? The 10+ price for a Powerex 1200v 600A module us under $300... 3 of those plus your ICs and parts and you're probably looking at keeping it under $1200. If you're dead set on 1800v and 800A you're probably gonna be spending some more $$ though. 

And of course, you could always use a bunch of 50-100A IGBTs or MOSFETs. That'd bring your price down a bunch.

As far as not using vector control- I don't know how well that's going to work. V/Hz is, as far as I know, only useful in applications where there is going to be little difference between the theoretical speed of the motor based on voltage and the actual speed. In a car, it's not uncommon to floor it from a dead stop, which would lead to serious timing issues unless you had incredibly slow throttle ramping. Unless there's something I'm not getting?


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## Technologic (Jul 20, 2008)

etischer said:


> Why wouldn't it be practical? With V/hz all you can do is control speed, with vector control you can control torque. Plus you get much more low speed torque.


It's not practical cost wise... of course it's better (Torque control for throttle response is also useful which the MCK201 allows).

A V/Hz model would give you graphs like (unless I'm mistaken):
http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php

Likewise you need encoders in the motor (rotor position sensors), hall sensors, etc for the thing to run properly...Also these things have to be set to specific motors via the on board registry interface... and it's not a simple point/click thing. Things like motor inductances etc must be input for max efficiency

I might still use the MCK201 and step down the design to survive 600v instead of 1200v, which would cut the costs by half for the parts and allow $50 or less IGBTs to be used.

The problem is the sensors/encoders... most motors don't have them installed... plus it requires an external throttle IC chip (though not too expensive) certainly increases board layout costs and complexity.

In the end this particular model after the PSU is added will have a 500-800 part count, not including any bus bars or temp cut offs etc.

The design was me building the largest and beefiest motor controller that had parts available... I never really intended for it to be built and sold. 1200v+ rated gate drivers, current sensors, 1500v rated DC filter etc... all VERY expensive.


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## Technologic (Jul 20, 2008)

Greenflight said:


> The 10+ price for a Powerex 1200v 600A module us under $300... 3 of those plus your ICs and parts and you're probably looking at keeping it under $1200. If you're dead set on 1800v and 800A you're probably gonna be spending some more $$ though.
> 
> And of course, you could always use a bunch of 50-100A IGBTs or MOSFETs. That'd bring your price down a bunch.
> 
> As far as not using vector control- I don't know how well that's going to work. V/Hz is, as far as I know, only useful in applications where there is going to be little difference between the theoretical speed of the motor based on voltage and the actual speed. In a car, it's not uncommon to floor it from a dead stop, which would lead to serious timing issues unless you had incredibly slow throttle ramping. Unless there's something I'm not getting?


I always intended to, if designing a V/Hz model, limit the amount of stop current the controller would allow to pass through by controlling the throttle via an IC controlled amplifier (with a significant delay and low faulting overcurrent setting).

V/Hz works just fine in theory for a car, just doesn't fit the "racing" mentality.

However I will attempt another go at a cheapened down version of this once this one is mostly finished... at the moment though it's difficult to explain just how much more expensive that design is than say the Zilla controller.
Just think parts counts in the 4-10 times range (IC prices at the 8-10 times expensive range) and 4 times as expensive (than the 1000 amp version) output stage... at a minimum... 3 separate PCBs will also be needed

I don't intend to source IGBTs from the US... just way too expensive.

If the Zilla's 1500-1800 price was the market value, such a controller would be $5000-8000... clearly I need to shorten things up a bit...


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## aeroscott (Jan 5, 2008)

from my reading svm lets us use less robust motors (non inverter rated)


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## Technologic (Jul 20, 2008)

aeroscott said:


> from my reading svm lets us use less robust motors (non inverter rated)


But those motors need encoders and some kind of position sensor (plus hall sensors)... most industrial motors don't in the first place.

An AC traction motor for the task can use a V/Hz though efficiency will drop to the high 80s low 90s, as far as practicality a SVM is about 3 times more complicated and needs a lot more parts.

I see the value in it, but not in the ability for DIYers to use it with industrial motors... Maybe they can, I don't know what the "standard list of features" usually are for industrial motors.


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## aeroscott (Jan 5, 2008)

true , encoders can be added . seams not to hard or expensive . But I find this stuff in the junk yards at 1 or 2 bucks per lbs.


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## etischer (Jun 16, 2008)

Technologic said:


> It's not practical cost wise... of course it's better (Torque control for throttle response is also useful which the MCK201 allows).
> 
> A V/Hz model would give you graphs like (unless I'm mistaken):
> http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php


 
I don't think it is possibe to get 100% torque at zero speed without vector mode. 

Think of it this way, at 100% speed you are supplying 230vac at 60hz. At half speed 120vac at 30hz. At 1% speed 2.3vac at 0.6hz. you can't expect 100% torque when supplying the motor 2.3 volts. You can put some DC boost in there, but I don't think you can get close to the performace as a true vector setup.

You can do sensor-less vector mode which does not use an encoder, it just needs current feedback.


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## aeroscott (Jan 5, 2008)

along that line i,ve been getting large caps from inverter welders , some are igbt and some moss . I haven't seen any come in in a while . but rack mount equipment with some nice wire , terminal blocks , filter stuff etc. any thing you guys can think of let me know .


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## etischer (Jun 16, 2008)

aeroscott said:


> from my reading svm lets us use less robust motors (non inverter rated)


The inverter duty rating is based on the insulation rating. You may havea a 230vac motor, but an inverter is supplying 600v pk-pk DC though a pwm. The insulation is rated for a higher voltage in a inverter duty rated motor. Sensorless vector, or v/hz, the motor should be inverter duty rated.


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## Technologic (Jul 20, 2008)

etischer said:


> I don't think it is possibe to get 100% torque at zero speed without vector mode.
> 
> You can do sensor-less vector mode which does not use an encoder, it just needs current feedback.


Sensorless vector is out of the question due to the poor load linearity inherent in a car (at least I personally wouldn't trust myself to design one that can compensate for a changing load).

I'm going back to the drawing board and see what I can come up with (since the only thing left in that design is the DAC at this point)... that damn current resistor sensing is still giving me issues... too much heat even at 0.001ohm


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## etischer (Jun 16, 2008)

Technologic said:


> that damn current resistor sensing is still giving me issues... too much heat even at 0.001ohm


Try buying a current transducer. What current range are you looking for, and what type of scaling do you need?


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## Technologic (Jul 20, 2008)

etischer said:


> Try buying a current transducer. What current range are you looking for, and what type of scaling do you need?


0-600 or 800A would be nice... 
Scaling should be something like a 1-2v minimum threshold... though I'm unsure exactly what you mean by scaling (ie. the datasheets give no specifics about it). 1-2v threshold at peak current.

Granted I don't think a current transducer will work either... at least not without changing out the code settings in the MCK201...


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## Greenflight (Sep 13, 2007)

etischer said:


> I don't think it is possibe to get 100% torque at zero speed without vector mode.
> 
> Think of it this way, at 100% speed you are supplying 230vac at 60hz. At half speed 120vac at 30hz. At 1% speed 2.3vac at 0.6hz. you can't expect 100% torque when supplying the motor 2.3 volts. You can put some DC boost in there, but I don't think you can get close to the performace as a true vector setup.
> 
> You can do sensor-less vector mode which does not use an encoder, it just needs current feedback.


I don't think this exactly how v/hz works. It is not related to the actual speed of the motor, just the position of the throttle sensor. So, assuming you had a minimal acceleration curve, you could be supplying 230vac to the motor at 60hz and the motor could still not be turning.

Vector mode essentially uses a measurement of motor RPM to adjust the v/hz ratio to account for variations cause by load.

That's why v/hz isn't so awesome for applications involving load.


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## Greenflight (Sep 13, 2007)

As for a current transducer- check this out. It's kind of expensive, but readily available surplus. I have one I pulled out of a forklift controller.


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## Technologic (Jul 20, 2008)

awesome I finally found a current sensor that can do this... and once more it's a high cost savings and can sense up to 1000A ($2 in 1 quantities).

http://www.sentron.ch/csa.htm

How I just have to redesign that stage and start assembling a parts list so I have a decent cost idea (and choose IGBTs so I can finally pick the correct values for the gate resistors and bootstrap caps). Such an amazing sensor... and it could potentially track every current draw per cell in a pack down to 0.5% accuracy (for BMS). That chip's 4ns delay in sensing is almost 100 times more quick than the resistor sensor... though a small microcontroller may be needed to output a gatekill signal for overcurrent based upon the signal received, I can't find something made for just that task premade in an IC... and though you could modify the MCK201 to cut off at a certain sensing voltage input from IFB0 and IFB1, that's not really a "cut and paste" sort of process.

On a totally separate note:

Regen occurs when the motor spins faster than the velocity the gate is dictating causing the back EMF to go back into the lines... Is the way to absorb this energy (since it's AC?) necessary to switch on all 3 high side IGBTs and then rectify to the DC voltage?

Is the voltage always the same as the inputted voltage more or less?

It's somewhat difficult to find any circuit information about this, but it's not "inherent in the design" in this case. The brake terminal can be rigged up for the task of switching all of the high side IGBTs on.


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## etischer (Jun 16, 2008)

Greenflight said:


> I don't think this exactly how v/hz works. It is not related to the actual speed of the motor, just the position of the throttle sensor. So, assuming you had a minimal acceleration curve, you could be supplying 230vac to the motor at 60hz and the motor could still not be turning.
> 
> Vector mode essentially uses a measurement of motor RPM to adjust the v/hz ratio to account for variations cause by load.
> 
> That's why v/hz isn't so awesome for applications involving load.


If you have 230vac @60hz and the motor is not turning, you will be drawing a ton of current. I don't think you can just connect a motor up across the line to 230vac. Here is a graph showing how v/hz works. At low speed you need to put some DC offset to gain low speed torque, here it is called "boost"


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## Technologic (Jul 20, 2008)

latest schematic... all of my instincts are telling me it's ok the way it is... however, the IFB0 and IFB1 (current sensor inputs) need to be reprogrammed upon a measured output to cut off at the voltage ... what voltage that is I can't say.

I'm also not 100% sure that the optoisolator will keep the gain the same for both channels... I may need a low voltage opamp in line instead... still weighing options.

Edit:
I've gone ahead and added it so you can see what's changed... the optoisolator on the current sensors won't stay (being replaced by two opamps to give a 2:1 gain)... just waiting for a reply to an email for choosing those.

http://img127.imageshack.us/img127/8287/part1m.png

I haven't decided on what outputs I want the controller to display... they can range from current/voltage sensors to full on projections onto LCDs with little to no real additional code changes, though the LCD would require decently expensive ($5-7 more) parts. But you can actually display the PWM signal, current sensor data and voltage data all at once on a screen with a DAC converter... pretty nifty.

With the option of using hall sensors OR encoders people can potentially modify industrial motors by adding hall sensors to each phase... a fairly cheap thing that could even be drawn up on another PCB for a few bucks (plug and play type deal)


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## Technologic (Jul 20, 2008)

ok current sensing stage is finished... at least I believe It'll be hands off on it from now on.

Since you can change the registry in the MCK201 to shut off from the overcurrent at a certain voltage (say 5v from that opamp) I think I will be using the gatekill for another thing... specifically a temp sensor on the output stages...

http://img27.imageshack.us/img27/6242/part1cpi.png

Link to the nearly finished schematic (about 75%)

Gain is 2:1 on the 2.5v max outputs from the sensors (2.5v being the point the flux is saturated... or about 800A) so the opamp should output upwards of 5v. I'm much more pleased with the current sensing at this point. Large shielding will need to go around each sensor... but besides that tiny thing to remember it's workable.

If anyone wants to pitch in I need to design a 1A 20v PSU, 3.3v of like 500mA and a 5v of like 1A or so... regulated. Probably going to do that on a separate PCB and have a DC-DC supply for 12v as well (so people don't have to try and find 300+v DC supplies if they choose to run this that high). Not sure what all of the average car's accessories take up amperage wise... maybe 20A? should be fairly easy to make a SMPSU for that.


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## Greenflight (Sep 13, 2007)

etischer said:


> If you have 230vac @60hz and the motor is not turning, you will be drawing a ton of current. I don't think you can just connect a motor up across the line to 230vac. Here is a graph showing how v/hz works. At low speed you need to put some DC offset to gain low speed torque, here it is called "boost"


That's exactly what I'm saying... Hertz is related directly to volts with a fixed ratio (except the boost, obviously). And volts is related directly to the position of the throttle pedal. Since the controller has absolutely no clue what the motor is doing, it just takes an educated guess using v/hz. So, if you floor the car from a dead stop, you will be supplying full voltage to the motor- and since the controller knows no better you will also be supplying full frequency.

In reality that's just a generalization, because most v/hz controller have a setting for acceleration so they don't go and do this. For a car, however, the acceleration would need to be extremely gentle to keep the controller from overshooting the motor.

Since vector control has a feedback system, it "knows" how fast the motor is turning, so it can still provide max voltage to the motor at low RPM at the same frequency at which a v/hz controller would only be supplying a couple volts. This is desirable because it allows near full torque and power across the whole rpm range.

Lookin good tech!


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## etischer (Jun 16, 2008)

If you ramp up too quickly, the motor will slip and stall. Atleast that is what happens with my setup. It will probably work fine on a bench with no load, but when the inertia of the load is much larger than the inertia of the rotor, problems occur. My car feels like the motor is cogging when it slips beyond the point it can sync. Once I'm above 3% speed, everything works like a dream. 



Greenflight said:


> That's exactly what I'm saying... Hertz is related directly to volts with a fixed ratio (except the boost, obviously). And volts is related directly to the position of the throttle pedal. Since the controller has absolutely no clue what the motor is doing, it just takes an educated guess using v/hz. So, if you floor the car from a dead stop, you will be supplying full voltage to the motor- and since the controller knows no better you will also be supplying full frequency.
> 
> In reality that's just a generalization, because most v/hz controller have a setting for acceleration so they don't go and do this. For a car, however, the acceleration would need to be extremely gentle to keep the controller from overshooting the motor.
> 
> ...


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## aeroscott (Jan 5, 2008)

etischer said:


> If you ramp up too quickly, the motor will slip and stall. Atleast that is what happens with my setup. It will probably work fine on a bench with no load, but when the inertia of the load is much larger than the inertia of the rotor, problems occur. My car feels like the motor is cogging when it slips beyond the point it can sync. Once I'm above 3% speed, everything works like a dream.


well put this is the area of concern . LTI says you can get a huge inductive load heating the rotor to the melting point ( extreme case ) .they went to switched reluctance to solve this ( very little rotor heating ) . My hope is this controller will be able to s. r. with little mods( diodes are added it cannot do a igbt to igbt short ) . but svm solves some of this problem with very low freq. and voltage ( like 3 hrz. at start up )


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## etischer (Jun 16, 2008)

aeroscott said:


> well put this is the area of concern . LTI says you can get a huge inductive load heating the rotor to the melting point ( extreme case ) .they went to switched reluctance to solve this ( very little rotor heating ) . My hope is this controller will be able to s. r. with little mods( diodes are added it cannot do a igbt to igbt short ) . but svm solves some of this problem with very low freq. and voltage ( like 3 hrz. at start up )


I've never heard of Switched Reluctance mode, but sounds like the motor has to be a Switched Reluctance motor. Sensorless vector should solve the problem.


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## aeroscott (Jan 5, 2008)

etischer said:


> I've never heard of Switched Reluctance mode, but sounds like the motor has to be a Switched Reluctance motor. Sensorless vector should solve the problem.


yes the motor is moded it's 3 phase ( or more ). my understanding sensors are a must for a ev . you need good position indication put put the wright power at the wright time . the controller needs to see the effect as the motor picks up speed . this timing needs to be vary good . check google for s.r. motors .


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## Greenflight (Sep 13, 2007)

aeroscott said:


> well put this is the area of concern . LTI says you can get a huge inductive load heating the rotor to the melting point ( extreme case ) .they went to switched reluctance to solve this ( very little rotor heating ) . My hope is this controller will be able to s. r. with little mods( diodes are added it cannot do a igbt to igbt short ) . but svm solves some of this problem with very low freq. and voltage ( like 3 hrz. at start up )


Most 3-phase controller ICs have an adjustable parameter for dead zones to prevent IGBT-IGBT shorts... I don't think that will be a huge problem.

I can imagine that high current, low RPM situations are bad for an induction motor the same way they are bad for a series motor- just sitting there and pulling a bunch of current is bad for anything. In that sense, I can see a small amount of throttle ramping being a good thing. Current limiting might be more useful though.


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## Technologic (Jul 20, 2008)

Greenflight said:


> Most 3-phase controller ICs have an adjustable parameter for dead zones to prevent IGBT-IGBT shorts... I don't think that will be a huge problem.
> 
> I can imagine that high current, low RPM situations are bad for an induction motor the same way they are bad for a series motor- just sitting there and pulling a bunch of current is bad for anything. In that sense, I can see a small amount of throttle ramping being a good thing. Current limiting might be more useful though.


In most situations throttle ramping would be the way to go, but in a DSP controlled AC controller that allows easy registry shifts (especially deadtime etc shifts with just inputed parameters) it's pretty easy.

On a separate note there's no way I can accurately design a Switchmode PSU without a spice program... and since the last thing I want to do is hand input MOSFET and other parameters, I need to figure out a way to download Pspice again.


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## Technologic (Jul 20, 2008)

etischer said:


> I've never heard of Switched Reluctance mode, but sounds like the motor has to be a Switched Reluctance motor. Sensorless vector should solve the problem.


Do you have any links on sensorless vector? is it pulling it via hall sensors or what? Because if so the MCK201 DSP can do that with just a registry change.


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## samborambo (Aug 27, 2008)

A few points:

Sensorless vector control is definately your best option. As others have pointed out, open loop V/F control is not appropriate for a torque control model. Vector control should be used but with the PID loop set up to regulate torque, not speed. Sensorless control has a drawback in that it can't sense the BEMF below a certain speed. For low speed control, positional feedback, speed feedback or open loop V/F could be used depending on the type of motor being driven.

The gate drive for the MOSFET or IGBT bridge is often the most time consuming component to design. Research the different drive options available - there are drawback to using capacitively coupled bootstrap gate drivers. Bootstraps don't offer any isolation from the battery/motor circuit which can be troublesome when looking at the overall system. A decision has to be made as to whether to isolate the control logic (DSP in this case) from the inverter drive or isolate it from the communications bus and human interface (or both!). I recommend looking into gate drive transformers to give isolation and more flexible control over the gate drive waveform.

Why a DSP? Seems very overkill. There's quite a few vector control solutions for microcontrollers (even PICs) that will fit the bill. Plus microcontroller code is a lot easier to faultfind, customise and reprogram in the feild.

Sam.


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## Technologic (Jul 20, 2008)

samborambo said:


> A few points:
> 
> Sensorless vector control is definately your best option. As others have pointed out, open loop V/F control is not appropriate for a torque control model. Vector control should be used but with the PID loop set up to regulate torque, not speed. Sensorless control has a drawback in that it can't sense the BEMF below a certain speed. For low speed control, positional feedback, speed feedback or open loop V/F could be used depending on the type of motor being driven.


I don't see how it's the best option... for all of the reasons you just said... it adds additional problems, many of which I neither have the time nor desire to fix (ie. I don't want to learn CMOS programming at any level).

That is not an open loop control circuit... you can disable it in the DSP and do a full on torque input control to external throttle inputs. You can choose either velocity or torque commands. ie. current and voltage respectively.



> The gate drive for the MOSFET or IGBT bridge is often the most time consuming component to design. Research the different drive options available - there are drawback to using capacitively coupled bootstrap gate drivers. Bootstraps don't offer any isolation from the battery/motor circuit which can be troublesome when looking at the overall system. A decision has to be made as to whether to isolate the control logic (DSP in this case) from the inverter drive or isolate it from the communications bus and human interface (or both!). I recommend looking into gate drive transformers to give isolation and more flexible control over the gate drive waveform.


The DPS is isolated from the inverter drive. I'll take a look at some transformers, half the point of IGBTs is the square wave form being necessary for efficiency... so I really don't want to modify that at all.



> Why a DSP? Seems very overkill. There's quite a few vector control solutions for microcontrollers (even PICs) that will fit the bill. Plus microcontroller code is a lot easier to faultfind, customise and reprogram in the feild.
> 
> Sam.


the DSP comes preprogrammed for full on hall or encoder based SVM with tons of features prepackaged making it possible to use industrial motors for the task (not to mention serial registry access... which the lack of in most controllers is one of my deepest hatreds).

I'm not a coder... at any level... and the DSP coding is basically set up for user interface programmability via their own application... a very sexy and cheap option in my opinion.

The alternative is designing lots and lots of coding... which you or anyone is free to do if they choose... but I simply won't do it under any circumstances (I seriously hate coding that much). If any minor compability coding is necessary that's fine, however as far as designing, learning and implementing the proper coding for either sensorless or full SVM control is out of the question... I just don't want to do it.


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## aeroscott (Jan 5, 2008)

Technologic said:


> Do you have any links on sensorless vector? is it pulling it via hall sensors or what? Because if so the MCK201 DSP can do that with just a registry change.


I had a link from google switched reluctance motor search . can't find it . that site showed a 150 lb.motor 20,000 rpm , 750 continuous hp . but other sites show them in animation and there's more as of late on control . the LTI guy said it dose not fallow motor theory , so figuring how to run it is hard . but they are getting more common like vacuum cleaners and washing machines . I think this will be advanced version after getting a induction motor going unless much more information becomes available .


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## Evan (Feb 20, 2008)

I just found this thread. As usual I am late to the party. 
As I am fond of saying only on Gallifray can one truelly be fashionabley late. 

Technologic - The IRF chip you are using is not a DSP. I suspect is a modified 8051. A DSP is a very different animal. Yes you can do SVM with something smaller than a DSP but it is tricky because of the heavy math requirements. You need ether large look up tables or very high speed to compensate. The reason to go DSP or something more powerfull is because the more precision you do with the processing the better it will work. I suspect that the SVM chip from IRF will work reasonably well but it will have it's limitations. The chip was originally meant to be used in an industrial control system machine called a VFD or in a robotic application as a servo. This is why torque is a presset value. Look at the manuals for something like a seimens simovert VFD and you will see what I am talking about.


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## Technologic (Jul 20, 2008)

Evan said:


> I suspect that the SVM chip from IRF will work reasonably well but it will have it's limitations. The chip was originally meant to be used in an industrial control system machine called a VFD or in a robotic application as a servo. This is why torque is a presset value. Look at the manuals for something like a seimens simovert VFD and you will see what I am talking about.


What limitations do you expect it will have?
I'd like to know if I should wash that design away because if it is something serious.

Looking at the design notes etc it seems to have highly selectable output characteristics from switching frequency to motor choices... and can fairly simply be tricked into regen braking as well.

Maybe there's something I overlooked on it.... but I'd rather like to know before I take on the laborious task of designing a 4 separate voltage output SMPS for up to 400v


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## Evan (Feb 20, 2008)

To get regen out of it is simple. Just don't let it apply breaking resistance. It naturally applies the proper signal to generate power out I think. If it does DC breaking I may be wrong. 

No matter what your output stage will still be good I think.


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## Technologic (Jul 20, 2008)

Evan said:


> To get regen out of it is simple. Just don't let it apply breaking resistance. It naturally applies the proper signal to generate power out I think. If it does DC breaking I may be wrong.
> 
> No matter what your output stage will still be good I think.


I need to contact IRF about that, because I don't believe it does output the signal to keep the high side drivers active. I believe the brake is a PWM signal, which maybe can be coupled to the gate driver during braking, but it says almost nothing about it in all of the data sheets.

And high praises on the output stage


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## Evan (Feb 20, 2008)

Well the chip is 3.3V logic unless I am mistaken which is where most if not all small microprocessors/FPGA/DSP are going now. 

Yes I though it was PWM not DC for breaking but what I meant to say was if it is DC we will have trouble.


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## Evan (Feb 20, 2008)

The limitations are in terms of efficency (# bits of precision) and other minor things you will have to design around.


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## david85 (Nov 12, 2007)

Well I'm late too. Better late than never.


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## samborambo (Aug 27, 2008)

Technologic said:


> I don't see how it's the best option... for all of the reasons you just said... it adds additional problems, many of which I neither have the time nor desire to fix (ie. I don't want to learn CMOS programming at any level).
> 
> That is not an open loop control circuit... you can disable it in the DSP and do a full on torque input control to external throttle inputs. You can choose either velocity or torque commands. ie. current and voltage respectively.
> 
> ...


T, you're missing the point. Its not appropriate to drive a traction motor in a car in a speed regulated mode (unless for cruise control). Almost every industrial drive application is speed regulation of a constant or known torque. This is not the case in traction applications where the load (and therefore the torque) are completely variable. To break it down simply (as has been said before), when you press down on the accelerator, you want an increase in TORQUE not SPEED. Off-the-shelf motor controller ASICs are usually set up for speed regulation and are probably not suitable.

The controller needs to be aware of how what the load is at any given time. For induction motors, the torque load is proportional to the slip (speed difference between the rotor and the EMF). For synchronous machines like BLDC motors, torque is proportional to the angle at which the rotor lags the EMF. So if you want a universal 3 phase controller, you need it to operate in two distinct modes - one for ACIM and one for BLDC/PMSM.

The inverter bridge in PWM is a voltage controlling device. The voltage of each inverter leg relative to 0V is proportional to the duty cycle applied to the gates. 

This is pretty much, in laymans terms, what goes on in vector control. In induction motor mode, the controller has to know the motor speed in order to know the EMF to apply to overcome BEMF. It also needs to know how much current to apply for the commanded torque. The current needs to be converted into a voltage based on the impedance of the motor. This voltage is summed with the EMF voltage and sequenced as a sine wave for each inverter leg.

PMSM/BLDC mode is similar but the phase angle becomes important for correct operation.

Torque and speed can be acquired from physical sensors but that creates additional complexity and more to go wrong. Sensorless control works by measuring the inverter current and BEMF to derive the torque and speed/position. Sensorless requires sensing 3 phase voltages and at least 2 phases of current.

When I mentioned using a microcontroller, I didn't suggest you start from scratch. This app note from Microchip should give you a good idea on what sensorless control entails:

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en023378

The source code can be modified for torque command instead of speed quite easily.

Sam.


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## Technologic (Jul 20, 2008)

samborambo said:


> T, you're missing the point. Its not appropriate to drive a traction motor in a car in a speed regulated mode (unless for cruise control). Almost every industrial drive application is speed regulation of a constant or known torque. This is not the case in traction applications where the load (and therefore the torque) are completely variable. To break it down simply (as has been said before), when you press down on the accelerator, you want an increase in TORQUE not SPEED. Off-the-shelf motor controller ASICs are usually set up for speed regulation and are probably not suitable.


You need to read the application notes on the IRMCK201 to understand... the MCK201 only requires a registry change for it to be a torque based vs speed based controller... BOTH are preprogrammed... no such modifications are necessary... this is why the IRMCK201 is so wonderfully perfect for this job...
http://www.irf.com/technical-info/refdesigns/dg-irmck201.pdf
It's also only $17



> The controller needs to be aware of how what the load is at any given time. For induction motors, the torque load is proportional to the slip (speed difference between the rotor and the EMF). For synchronous machines like BLDC motors, torque is proportional to the angle at which the rotor lags the EMF. So if you want a universal 3 phase controller, you need it to operate in two distinct modes - one for ACIM and one for BLDC/PMSM.


 I only plan for this to work directly to induction 3 phase motors... if anyone wants something different it'd be on their shoulders to modify... the stark issue in offerings right now is a controller up to 300-400v (anything over 80v doesn't exist) that can do regen + work on industrial motors in traction applications... *this can*. And it only took about 100 hrs to design/research


> The inverter bridge in PWM is a voltage controlling device. The voltage of each inverter leg relative to 0V is proportional to the duty cycle applied to the gates.
> 
> This is pretty much, in laymans terms, what goes on in vector control. In induction motor mode, the controller has to know the motor speed in order to know the EMF to apply to overcome BEMF. It also needs to know how much current to apply for the commanded torque. The current needs to be converted into a voltage based on the impedance of the motor. This voltage is summed with the EMF voltage and sequenced as a sine wave for each inverter leg.


 Right and instead of working out that math myself... you can simply modify the registry of the IRMCK201... it can read such data through precise encoders... or less precise but still useable hall sensors to each phase. Again user selectable for application with only a registry change.



> PMSM/BLDC mode is similar but the phase angle becomes important for correct operation.
> 
> Torque and speed can be acquired from physical sensors but that creates additional complexity and more to go wrong. Sensorless control works by measuring the inverter current and BEMF to derive the torque and speed/position. Sensorless requires sensing 3 phase voltages and at least 2 phases of current.


Again I know this, and I thank you just the same for bringing it up. *Sensorless can be done with the MCK201 with registry changes and hall sensors.* The programming already allows it and that circuit already has those portions designed in.

I'm sorry if I didn't explain this clearly before, it's easy for me to get confused by many different terms for the same thing . However there's two position sensor options... you can use the current sensors on phase V and W + 3 hall sensors one per phase... or use an encoder...the design has options for both and I will include a PCB for a plug/play 3 hall sensors in due time.



> When I mentioned using a microcontroller, I didn't suggest you start from scratch. This app note from Microchip should give you a good idea on what sensorless control entails:
> 
> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en023378
> 
> ...


I'll have a look at it thanks... I'm looking to make a smaller version once this one is up and running after some tinkering... the SWPS is going to give me issues, but my library at my grad school is the largest in the southeast (Duke)... and I must say they had some nice books so far I'll be picking up tomorrow so I can SPICE up a sim and have most of this circuit (and a DC/DC 400v-12v 10A converter) done and out the door by this weekend.

If I run into any issues fixing an error in this I will just hop over to the EE grad school here and get a prof to help me troubleshoot... I don't pay $41k/yr for nothing


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## Evan (Feb 20, 2008)

Technologic - There is no such thing as CMOS programming. 

samborambo - No, though you are only partially wrong. In *many* industrial apps you want constant torque. However, this is not absolutely true. Once more in an EV you want to used closed loop control for speed and torque. Pressing down the pettal increases speed (velocity). Torque changes are tied to acceleration. So just increase torque by some constant multiplied by the derivative of the speed.

You will notice as I and others have said in now no less than 3 other threads that using microchips source code means they own that part of your design. Granted the SVM algorithm in Technologics selected IRF chip are owned by IRF but then again so is what ever processor we use.

You description of how vector controles is technically correct but over simplified. If you think you can do better try to do what I am make an SVM implimentation in some firmware.


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## Technologic (Jul 20, 2008)

Evan said:


> You will notice as I and others have said in now no less than 3 other threads that using microchips source code means they own that part of your design. Granted the SVM algorithm in Technologics selected IRF chip are owned by IRF but then again so is what ever processor we use.
> 
> You description of how vector controles is technically correct but over simplified. If you think you can do better try to do what I am make an SVM implimentation in some firmware.


Indeed... I personally don't mind... it's part of buying the chip, the right to use the code. You might have potential legal issues if you pulled the code out and put it in a DSP and then sold it as a cheaper SVM chip... but It'd be an impossible thing to prove.

IRF isn't the only SVM chip company... I found a few others (though not as feature rich).

And as far as CMOS programming hell if I know  I just see that referenced over and over in these docs.

I'm surprised since the engineers showed up they didn't drool over the current sensors I found... maybe they aren't that special... but it took a very long time to find them... good to 1000A and up to 0.5% accuracy with almost no real heavy design to get them to work unlike using a hall sensor for it.

http://www.sentron.ch/csa.htm


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## Evan (Feb 20, 2008)

Technologic - When they said CMOS programming they meant settings stored in CMOS by which they mean the Flash or EEPROM memory implimented in CMOS. People trying pick terms just to sound impressive. 

Not to burst you bubble but the really impressive current sensors are on lower current where the noise ratios are higher.


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## Technologic (Jul 20, 2008)

Evan said:


> Not to burst you bubble but the really impressive current sensors are on lower current where the noise ratios are higher.


haha well I figured as much, considering SNR and all. Same goes with audio amplifiers from way back when I was messing with those.

 still I was happy when I found them.


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## samborambo (Aug 27, 2008)

Evan said:


> Technologic - There is no such thing as CMOS programming.
> 
> samborambo - No, though you are only partially wrong. In *many* industrial apps you want constant torque. However, this is not absolutely true. Once more in an EV you want to used closed loop control for speed and torque. Pressing down the pettal increases speed (velocity). Torque changes are tied to acceleration. So just increase torque by some constant multiplied by the derivative of the speed.
> 
> ...


Over simplified because not everyone reading this has a degree in mechatronics or similar. I'm trying to keep the audience open here.  

Yes, I have said this before and I'll say it again. Microchip source code is usable for this purpose. I don't know what the legal issues are for modifying it and selling it in a closed source model but frankly I don't care and neither should anyone else on this forum. If you're taking advantage of an open design for profit, you have no place on this forum.

Evan, you weren't the one thinking of implementing SVM in JAVA where you?

This is the Microchip AN for advanced induction motor control with field weakening:

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en536065

Also worth the read. Sorry, didn't realise you were after induction only.

Great news that your controller part can do torque control with minor change. I still believe a Microchip $4 part is much more flexible. Come on, modifying a little C code never hurt anyone


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## Technologic (Jul 20, 2008)

samborambo said:


> This is the Microchip AN for advanced induction motor control with field weakening:
> 
> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en536065
> 
> ...


Depending if I can get ahold of some MCK201's even for $20-25/each we'll see... they're not easy to come by outside of samples so I might have to look elsewhere (though I have some tricks up my sleeves to get enough to populate boards with).

I can get samples in to fix up the circuit nice and pretty (and make it work the way I want) and get some boards printed... but beyond that I don't know where I can source them. Arrow has 1 qtys of them for $11.56 but with a 12 week lead time... thinking about ordering 20 here so they'll be in by July blah.

But that's how long it might take to perfect the circuit and get PCBs in... so might as well? I'll be out of the country in May-June anyway...

Feel free to modify some C... I'd be more than happy to work with two designs at once and help out however ... whether fronting the money for prototypes or whatever.

All of this is quite a load of entertainment for me...


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## Dennis (Feb 25, 2008)

Honestly I do not think anyone should attempt this project unless they know exactly how an AC induction motor behaves. Making an AC induction motor have the same abilities as a DC motor is extremely complex. This speed control* with* torque control technology has been out for about only 20 years or so since microprocessors finally got powerful enough to do the computations so this is not a very mature technology in comparison to DC motor controls.

I suggest anyone attempting this project to have 100% understanding of what this PDF handout from MIT says about controlling AC induction motors: http://dspace.mit.edu/bitstream/han...0-2050-4706-A231-8C27291E1BBB/0/chapter10.pdf. 

If this stuff makes clear sense then by all means lets be serious about this project so that this can become a competitor against the Zilla DC motor controllers. All I see here is talk, but no video clearly showing an AC motor being controlled by a homebrewed AC controller. I myself only know the basics, even though I am an Electronics Engineer Technologist which is one step below an EE and so I do not know about the rigurous theories just the basics to do repairs on already made products sort of like a TV repairman.


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## Technologic (Jul 20, 2008)

Dennis said:


> \This speed control* with* torque control technology has been out for about only 20 years or so since microprocessors finally got powerful enough to do the computations so this is not a very mature technology in comparison to DC motor controls.
> 
> I suggest anyone attempting this project to have 100% understanding of what this PDF handout from MIT says about controlling AC induction motors: http://dspace.mit.edu/bitstream/han...0-2050-4706-A231-8C27291E1BBB/0/chapter10.pdf.
> 
> If this stuff makes clear sense then by all means lets be serious about this project so that this can become a competitor against the Zilla DC motor controllers. All I see here is talk, but no video clearly showing an AC motor being controlled by a homebrewed AC controller.


I'm not exactly sure what you expect...
I've only had that schematic to that point for 2 days now. 

At any rate that MIT paper isn't too terribly helpful, it leaves out a lot of information that'd be necessary to actually design/program one from scratch. There's a number of conditions necessary conditions that must be met including the inputting and calculation of lots an lots of cosines/sines based upon motor position to find out rotor speed etc (this is done through multi-variable differentiation if I'm not mistaken).

And at any rate, the MCK201 has this all preprogrammed in... Likewise I'll be disappointed if this "only competes" with the Zilla 

If you wanted to map dr/dt (difference of the changing angle) using cosine you'd need a function such that the angle of change is known and the width of the rotor is known (ideally) though the width of the rotor can also be found through complex variable analysis. (ie. this would be a sensorless system that checks both current and voltage and compares it to find out the times the coils pass the stators).

if x^2 + y^2 = 4 (8 inch motor or so) you'd need to know either sqrt(y^2-4) or sqrt(x^2-4) in order to solve postion... however this can only be done with specifically known motor parameters

Ie. an equation such that cos(x), sin(x) (for the x,y coordinates on a circle) can be derived if you know the length of the coils... however, to compensate for the fact many motors can be swapped in motor controllers generally have it programmed to sense the rotor position via the increased voltage/current as it passes near the stator coils.









SVM control senses when current (torque) is at it's maximum (a set angle from the stators) but does not let the rotor coils reach completely perpendicular to the stator windings... if they do you have a V/hz model and low torque during low RPM (because it has less torque on top of the stator coils and less moving mass). This is somewhat simple and the MIT formulas showing the derivative of the current should be sufficient in telling the max/mins (zeros) and then using those functions to shift the timing and slip respectively.

The fundamentals (and formulas in that MIT paper you linked) are simple, though anyone in their right mind will still have to look up formulas... I doubt more than 10 people in the world have that kind of thing memorized.

I don't really feel threatened by designing something with the MCK201... I'm fairly certain I will get it to work... but you need to learn patience... people talk before work gets done so they don't spend 2000 hours fixing something.


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## Dennis (Feb 25, 2008)

If you know Clarke transformations and really think Field oriented control is "easy" then more power to you. Real EE's even have trouble with this stuff so maybe you got something figured out that they don't......What exactly is you field of expertise? I know that Tessecle (however he spells it) is a real EE.


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## Technologic (Jul 20, 2008)

Dennis said:


> If you know Clarke transformations and really think Field oriented control is "easy" then more power to you.


I don't but those equations and differentiations are basic calculus at best (more pre-Calc in my opinion)... likewise I don't intend to CODE the thing which I've said more than a few times.

If there's a particular reason the IRMCK201 will fail for the task please feel free to provide it as I'd hate to waste time on something that won't work.


> Real EE's even have trouble with this stuff so maybe you got something figured out that they don't......What exactly is you field of expertise? I know that Tessecle (however he spells it) is a real EE.


I've never been one to put much stock in what "real" people in a field say... because generally they're just as wrong as anyone else. I'm a 1st year (well 2nd year in 3 weeks) J.D student at Duke University's law school. I can tell you that 2nd and 3rd year students still forget the 4 conditions for liability from the model penal code... even at a top 10 ranked law school. So forgive me for not putting much stock in the abilities and knowledge that a simple 4 year degree gives (especially one that generally only requires 15 classes to get... many of which are basic math courses up to multivariable derivatives). Even at my undergraduate school the electrical engineering department in comparison to the biomedical was hardly challenging for the students.

I have 3 bachelor degrees (2 B.A's and a B.S) from Duke University as well... in Classical Studies, Philosophy and Oceanography. While I knew very little about this subject 3 weeks ago... I have no doubt I can overcome whatever is necessary to make it work well.

I probably find the formulations easier because it's not necessary for me to derive equivalencies in the form of coding... however, the fundamental concepts are genuinely straightforward. Despite the poor explanations given in that MIT paper the actual information is resoundingly easy to understand.

Cheers.


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## Evan (Feb 20, 2008)

samborambo - Dude read my old posts. I both dislike java in general but particularly for things like this. It is just to bloated owing to it's interprited architecture. I am not scared of programming unlike Technologic who like many EE people is a programaphobe. I could modify the assembler code from microchip (it isn't C) but I want to have the licence be GPL or equivilant. The microchip code, which I was the first to point out on that first thread, is licenced. Once more I am not a fan of the DsPIC architecture. I would rather use a DSP or PLC. Currently I am leaning tward the FPGA well CPLD. It is in my opinion easer to get nice real time responce from a PLD than from a uP.

Mechatronics is bull you wouldn't learn computer, mechanical or electronics engineering.

Oh and one more thing sensorless is junk for this application.

Dennis - Why would you try to discourage anyone who wants to from trying this. The worst case is we all end up burning up some otherwise fine silicon. My time is cheap I don't mind trying to help people. Why waste yours trying not too?

I am also an EET but where do you get off calling the degree less than an EE? EET varies based on the school. At macintosh or where ever it is a technicans degree. 
At a real school it is just the name used for the night program in EE. I studied the related theoretical physics including a complete class on motors. I also got a lot of advanced math, though I opted for that it wasn't required. I have seen many of my schools day EE courses and they are the same give or take a little thoeretical work. Almost every electronics class I had culminated in a design project at the end. These were not all simple cookbook problems. I got a few classes in design too. I and many other people I have studied with have worked as electronics design engineers. My senior design project (at Northeastern it is called Capstone) was a medical device. I designed the hardware, software and even redesigned the mechanical function of the machine. Granted the lab I was working for didn't change the mechanical parts to my dismay but in the end they admitted I was correct too. He by the way had a Ph.D in EE. Don't malign the degree. I frequently don't agree with technologic. Heck just ask that PhantomPholly guy there are whole threads devoted to our dissagreements on social issues. However, Technologic is very smart and while he may lack experiance he will never gain it if he doesn't try and yes occationally fail. 

It has taken me a few weeks of work to figure out that math. This is owing to two things.
A) I was never great at 3Phase circuit analysis. 
B) I was never great at vectors.
However, to impliment this you don't even have to really understand it. People have in various places on the internet worked out the math for us. I am just a curious person. Now all I have to do is write those equations using something like CORDIC into VHDL. That should keep me busy for quite a while. 

Technologic - I have friends who went to MIT. Never read anything written by an MIT proff for students. They have what they call "The MIT way." Bascially they selectively omit stuff to make the students work harder to understand it. I think this is counter productive to the actual teaching but I guess it is about pushing peoples work ethic and conceptual thinking. It has always seemed to me that a lot of peope who get into MIT do so because they have great memory not great abstract thinking.


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## Technologic (Jul 20, 2008)

Evan said:


> However, Technologic is very smart and while he may lack experiance he will never gain it if he doesn't try and yes occationally fail.
> 
> It has taken me a few weeks of work to figure out that math. This is owing to two things.
> A) I was never great at 3Phase circuit analysis.
> ...


Indeed it will  good luck 



> Technologic - I have friends who went to MIT. Never read anything written by an MIT proff for students. They have what they call "The MIT way." Bascially they selectively omit stuff to make the students work harder to understand it. I think this is counter productive to the actual teaching but I guess it is about pushing peoples work ethic and conceptual thinking. It has always seemed to me that a lot of peope who get into MIT do so because they have great memory not great abstract thinking.


Been down that train for the first 4 years of my college life. Selective omissions, trick questions, etc is the only way to distinguish between two kids that both made 1550s on their SATs or 175s on their LSATs (like I did).

I've gotten C's in 1 class then A's in the same exact class/next class level taught by someone else. Took 2nd year physics at a state college (UNC) and got an A with no prior classes in the subject outside of high school, took introduction to comp sci at Duke and got a C+... explain that one to me 

People forget that the average graduating GPA from top 10 schools isn't 3.7-3.8 like at state colleges... it's a 3.1-3.2. How on earth do you make a school of geniuses, photographic memory kids and top worldwide doctoral candidates get that low?(about 40% of my undergraduate body was from other countries) You trick them... and weigh the curve so only 10% of people get A's every semester. 

What's worse is that the two people I met during undergrad that had limitless potential (one of whom spoke 7 languages fluently) are now working at Random House publishing for $10/hour and working for Microsoft writing code respectively.

A BME friend had a 2.9 and got a 41 on the GMAT.... sighs


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## Evan (Feb 20, 2008)

Technologic - The first few years at MIT for undergrads all classes are pass fail because of the high suicide rate. I don't agree with your analysis of the GPA numbers, but that would likely lead us into another long drawn out disagreement and I would rather actually get our projects done.

I was not suggesting your would never get this thing to work, only that it would likely not happen on the first try. Yet another reason for building a model.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - The first few years at MIT for undergrads all classes are pass fail because of the high suicide rate. I don't agree with your analysis of the GPA numbers, but that would likely lead us into another long drawn out disagreement and I would rather actually get our projects done.
> 
> I was not suggesting your would never get this thing to work, only that it would likely not happen on the first try. Yet another reason for building a model.


Hmmm interesting strategy.

However, yeah I know you weren't suggesting that... I just couldn't resist bitching about my undergraduate school 

I plan to test the output stage first and work my way back... using incredibly cheap IGBTs with "similar" specs to whatever larger ones I decide on... that way if I burn them up due to inductance issues or capacitance issues with the bootstraps I won't be weeping over $300 of smoldering semi's

I found a supplier of 1200v 300uF (though I still need to get a hard number for that DC filter) film caps with low ESR... but I sort of want to go smaller and more in parrallel since you can cut inductance by a HUGE amount if you parallel caps... same with ESR.
15x20uF 1200v caps is only $10 and has 1/15th the inductance of the same 300uF single cap.


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## Evan (Feb 20, 2008)

Technologic - Yea well I frankly have complained too much already about my time at NEU. The thing is that over time I got them to change the way they did some things.

Well, I hate to burst your bubble but the odds that you will get the thing scaled up correctly the first time a not in your favor ether. Etchier is not only smart he is lucky.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - Yea well I frankly have complained too much already about my time at NEU. The thing is that over time I got them to change the way they did some things.
> 
> Well, I hate to burst your bubble but the odds that you will get the thing scaled up correctly the first time a not in your favor ether. Etchier is not only smart he is lucky.


There are ways to protect them though... at least protect them from becoming smoldering  placing resistors in line to limit power flow etc, in line fuses  things you'd never want in the actual finished version but it'd at least hopefully save your semis.


you're really not bursting my bubble  if I can get it to work I will... in one form or another. Generally when starting amplifiers I always had lightbulbs etc in line with the PSU so it couldn't draw enough power to break itself.... if the light bulb was on during idle it meant something was wrong... etc.

Any suggestions on proper methodology are much appreciated though


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## Evan (Feb 20, 2008)

Technologic - There is an old joke about the fuse used to protect the transistor. The fuse is rated at the continous power needed to burn the transistor out. The transistor can still be zapped with a high enough spike that it can make it threw before the fuse has enough time to burn up. You can only design things to avoid the disasters you can see, the ones you can't...

I am starting small because I know I am going to over look something.


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## aeroscott (Jan 5, 2008)

Evan said:


> Technologic - There is an old joke about the fuse used to protect the transistor. The fuse is rated at the continous power needed to burn the transistor out. The transistor can still be zapped with a high enough spike that it can make it threw before the fuse has enough time to burn up. You can only design things to avoid the disasters you can see, the ones you can't...
> 
> I am starting small because I know I am going to over look something.


that makes me think of the smart fuse or breaker based on hall effect and transistor switch , that can be programed to trip . I enjoyed the education discussion and insight .


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## Evan (Feb 20, 2008)

airoscott - How would you make that trip in time?


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## aeroscott (Jan 5, 2008)

Evan said:


> airoscott - How would you make that trip in time?


 I thought the driver board has that function . but are you saying that because the igbt has slow turn off , the damage would already be done . my understanding of the s.r. motor controller cannot short direct giving a little time to shut down


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## Evan (Feb 20, 2008)

aeroscott - There are eventuallities that can cause shorts or near shorts. A failure of one motor phase to match it's proper impedance can cause the other two to grow in power use exponentially very quickly. There are some faults you just can't protect against completely.


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## Technologic (Jul 20, 2008)

Evan said:


> aeroscott - There are eventuallities that can cause shorts or near shorts. A failure of one motor phase to match it's proper impedance can cause the other two to grow in power use exponentially very quickly. There are some faults you just can't protect against completely.


Evan.. here's stupid question (stupid because I believe I've been thinking about this the wrong way).

If you wanted to get 700kw of power out of 3 phase motor controller would each IGBT only need to be rated for 1/3rd of the power if you wanted to do the same with a DC controller?

I'm asking for obvious reasons that I somehow overlooked the fact these would functionally be in parallel with one another... but since each high side driver is only open one at a time maybe I'm right that they all need to be full rated?

Thanks  excuse this foolish question


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## aeroscott (Jan 5, 2008)

Evan said:


> aeroscott - There are eventuallities that can cause shorts or near shorts. A failure of one motor phase to match it's proper impedance can cause the other two to grow in power use exponentially very quickly. There are some faults you just can't protect against completely.


in this example , how fast do you think would get protection ( with over rated igbt's , etc to give more time )


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## aeroscott (Jan 5, 2008)

tecnologic , i think it's only 1.3 over single phase can't remember for dc . and that my be dependent on hz.


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## Technologic (Jul 20, 2008)

aeroscott said:


> tecnologic , i think it's only 1.3 over single phase can't remember for dc . and that my be dependent on hz.


What do you mean by 1.3 over single phase?

I was under the impression that AC inverters required 6 IGBTs rated at 1200v x 600A to achieve the same (well same DC draw) power levels as a single phase IGBT would for a DC supply. Are you saying it's 1.3 times over that?

the RMS thing isn't what I meant... the IGBTs are actually in parallel with each other so the effective amperage seen per IGBT could be lower.


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## Evan (Feb 20, 2008)

Technologic - 700KW is way way over anything practical for a car IMHO but if you must...

I suspect it is 1/3 but that is not the RMS ratings you have from the motor. I will have to look this up. Don't forget about things like starting current/voltage (wye/delta). You also have to figure a little excess, though I don't yet know how much. Derating parts of this high a power is not my strong suite. I think this involves the square root of 3 for some reason I can't recall right now. I need sleep.

Airoscott - I was throwing it out there in the hopes that someone else would see something I have not.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - 700KW is way way over anything practical for a car IMHO but if you must...
> 
> I suspect it is 1/3 but that is not the RMS ratings you have from the motor. I will have to look this up. Don't forget about things like starting current/voltage (wye/delta). You also have to figure a little excess, though I don't yet know how much. Derating parts of this high a power is not my strong suite. I think this involves the square root of 3 for some reason I can't recall right now. I need sleep.


Well the sqrt(2) is the RMS of an Sine wave. 

700kw is way way over... I was merely using that as a max IGBT rated capacity  At any rate I've found some really nice IGBTs for the task so I am just wondering ...

I remember the starting current and peak current thing being potentially very high voltages (ie. ratin the caps higher due to inductive surges etc.


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## Evan (Feb 20, 2008)

Yes I know what RMS is. But the sqrt(3) turns up a lot in 3 phase math. Converting power from a threw phase to single phase system for example.

I really have to read more in the morning.


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## aeroscott (Jan 5, 2008)

the phases overlap about 30% ( 30% parallel ). that's if i remember wright . I would think inverters can change the shape therefor the over lap .


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## samborambo (Aug 27, 2008)

T, the current of each phase leg is 1/sqrt(3) or 0.577 of the total current.

eg: Power = 700kW, RMS voltage = 700V, total RMS current = 1000A, RMS phase current = 577A


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## Technologic (Jul 20, 2008)

samborambo said:


> T, the current of each phase leg is 1/sqrt(3) or 0.577 of the total current.
> 
> eg: Power = 700kW, RMS voltage = 700V, total RMS current = 1000A, RMS phase current = 577A



Good to know thanks... can cut down the prospective sizing by half 

Means the output stage will cost about $200


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## samborambo (Aug 27, 2008)

FYI, max RMS voltage (phase to phase) out of an inverter is:

(Vbatt - 2*Vce[sat])/sqrt(2)

Eg: Vbatt = 1000V, Vce sat = 2, Vrms = 704V

For phase to (virtual) neutral voltage as used in star connected loads, divide the phase to phase RMS voltage by sqrt(3).


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## samborambo (Aug 27, 2008)

There's a supplier here in NZ thats doing 1200V, 100A (continuous) inverter six packs for around US$50. I bought one a while back but haven't used it yet - still sitting in my junk box. I've ear marked it for my electric motorbike project. Something similar would be good for testing. Here's the website:

http://www.surplustronics.co.nz/shop/product-CT0560.html

Sam.


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## Technologic (Jul 20, 2008)

samborambo said:


> There's a supplier here in NZ thats doing 1200V, 100A (continuous) inverter six packs for around US$50. I bought one a while back but haven't used it yet - still sitting in my junk box. I've ear marked it for my electric motorbike project. Something similar would be good for testing. Here's the website:
> 
> http://www.surplustronics.co.nz/shop/product-CT0560.html
> 
> Sam.


Here's my testing 
http://cgi.ebay.com/1-Fuji-Electric...5|66:2|65:12|39:1|240:1318|301:0|293:1|294:50

I found a 1200v 200amp 6 pack in china for $74 in quantities over 20 (Fuji brand) That's likely what I'll be using for this after testing... the alternative of that is using 3 x 400amp dual phase ones for about $74/each in the same quantity.

Thanks for that link though... but if I can get that IGBT locally for $10... that'll be a great tester... if I melt it I will have to order some from your source


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## Dennis (Feb 25, 2008)

> Dennis - Why would you try to discourage anyone who wants to from trying this. The worst case is we all end up burning up some otherwise fine silicon. My time is cheap I don't mind trying to help people. Why waste yours trying not too?



I am not trying to be discouraging I just don't want to see this guy give up when his designs fail a few times. I mean he is spending his money on the parts and is going through the trouble of showing off his schematic to us and plans to make no profits from his designs. If he is okay with that then fine, if not then someone else needs to take the reins so this project can become a reality so the DIY hobbyist will have something that is more efficient, proven relaible design. Too many times I have seen good ideas float around, but people seem to give up so soon..



> I am also an EET but where do you get off calling the degree less than an EE? EET varies based on the school. At macintosh or where ever it is a technicans degree.


MY EET degree is a 2-year program. Basically my degree allows me to repair already designed products OR to prototype the EE's designs on bread boards. In the EET program I took there is no rigurous theories that the EET needs to know. We only use the *MOST important fundemental theories *that are required to say repair a tv or radio for example, but the theories such as If I wanted to design a transformer to be 98% efficient, 700VA, and have an input voltage of 240 Volts RMS 60HZ with output of 24 Volts RMS or build a 3-phase motor for example are not taught in the 2-year program I took ( I can repair them though). We do some circuit designs such as amplifiers, digital, transistors, basic AC and DC impendence networks up to the advance network theorems such as Thevenin's, Mesh analysis, Nodal Analysis, etc...




> At a real school it is just the name used for the night program in EE. I studied the related theoretical physics including a complete class on motors. I also got a lot of advanced math, though I opted for that it wasn't required. I have seen many of my schools day EE courses and they are the same give or take a little thoeretical work. Almost every electronics class I had culminated in a design project at the end. These were not all simple cookbook problems. I got a few classes in design too. I and many other people I have studied with have worked as electronics design engineers. My senior design project (at Northeastern it is called Capstone) was a medical device. I designed the hardware, software and even redesigned the mechanical function of the machine. Granted the lab I was working for didn't change the mechanical parts to my dismay but in the end they admitted I was correct too. He by the way had a Ph.D in EE. Don't malign the degree. I frequently don't agree with technologic. Heck just ask that PhantomPholly guy there are whole threads devoted to our disagreements on social issues. However, Technologic is very smart and while he may lack experience he will never gain it if he doesn't try and yes occasionally fail.



Maybe your program is different. Out of curiostiy though what books did you guys use? Here are the ones I had to use:


_Essentials of Circuit Analysis _by* Robert L. Boylestad *

_Digital Systems_ by* Ronald J. Tocci, Neal S. Widmer and Gregory L. Moss*

_Electronic Devices and Circuit Theory_ by *Robert L. Boylestad and Louis Nashelsky*

_Engineering Programming C, MATLAB, JAVA_ by *Mark Austin and David Chancogne*

_Analog Integrated Circuit Applications_ by *J. Michael Jacob*

_PIC Microcontroller: An Introduction to Software and Hardware Interfacing _by *Han-Way Huang* (I hate this book and did not like the class  )
_Modern Industrial Electronics_ by *Timothy J. Maloney*

_CompTIA A+ Guide to Managing and Maintaining_ _Your PC_ *by Jean Andrews*

About the LINE current of a 3-phase motor. It depends on if it is WYE configured or DELTA configured. If DELTA configured then the line current is 1.73 times that of the phase leg current or 1.73*Iph = IL. If WYE then the current is Iph = IL.


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## Technologic (Jul 20, 2008)

Dennis said:


> I am not trying to be discouraging I just don't want to see this guy give up when his designs fail a few times. I mean he is spending his money on the parts and is going through the trouble of showing off his schematic to us and plans to make no profits from his designs. If he is okay with that then fine, if not then someone else needs to take the reins so this project can become a reality so the DIY hobbyist will have something that is more efficient, proven relaible design. Too many times I have seen good ideas float around, but people seem to give up so soon..


I tend not to give up much  I'll figure this out till I have it working... after that I can decide what I will do with the finished design... I vaguely like the idea of getting some PCBs assembled minus the output stages and relaying them out into group buys of some kind... I dunno we'll see if it's worth my time later...
As I said before though, this will likely not be used by me in my own build project.

Well this another reason for the IRMCK201 being sexy 

I got a response to my question about what is the waveform the brake pin outputs... where is what they said:
Here is the answer from the motor control application group : 

1) BRAKE pin output is a DC signal. It turns on when the DC Bus voltage rises above 380V and turns off when the DC Bus voltage drops below 360V.

2) To do regenerative braking, you can simply set the Regen Limit field in the spreadsheet to a positive number. The system will do the regenerative braking by continuing to provide voltage synchronized to the motor angle (by SVPWM), except with power flowing out of the motor and being stored on the DC Bus, pumping up the voltage. If the motor is running at some speed where you want to brake it, set a lower speed setpoint and make sure the deceleration rate is faster than it would coast down without braking. The regeneration current will be specified by the Regen Limit field.

Regards
International Rectifier

Pretty damn easy... they didn't even talk about that in the design notes 

I guess the brake pin can go directly into a circuit to do an emergency fault condition braking


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## samborambo (Aug 27, 2008)

Dennis said:


> About the LINE current of a 3-phase motor. It depends on if it is WYE configured or DELTA configured. If DELTA configured then the line current is 1.73 times that of the phase leg current or 1.73*Iph = IL. If WYE then the current is Iph = IL.


Sorry Dennis, I should have been more clear. It is the current of each inverter leg (as you correctly point out, the LINE current) which can be thought of as a delta config but with a moving neutral. You're right, the phase current of the motor windings are dependent on delta/wye config of the motor but I was referring to the inverter.


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## samborambo (Aug 27, 2008)

Technologic said:


> 1) BRAKE pin output is a DC signal. It turns on when the DC Bus voltage rises above 380V and turns off when the DC Bus voltage drops below 360V.
> 
> 2) To do regenerative braking, you can simply set the Regen Limit field in the spreadsheet to a positive number. The system will do the regenerative braking by continuing to provide voltage synchronized to the motor angle (by SVPWM), except with power flowing out of the motor and being stored on the DC Bus, pumping up the voltage. If the motor is running at some speed where you want to brake it, set a lower speed setpoint and make sure the deceleration rate is faster than it would coast down without braking. The regeneration current will be specified by the Regen Limit field.
> 
> ...


This can be done with a comparator configured with some hysteresis (ie: a Schmitt trigger). That way you can fine tune the voltage set points for the DC brake cutting in/out if the IRMCK201 doesn't provide changing these points. I'd recommend setting the cut in to just above the battery Vmax and cut out 5% below.


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## Technologic (Jul 20, 2008)

samborambo said:


> This can be done with a comparator configured with some hysteresis (ie: a Schmitt trigger). That way you can fine tune the voltage set points for the DC brake cutting in/out if the IRMCK201 doesn't provide changing these points. I'd recommend setting the cut in to just above the battery Vmax and cut out 5% below.


That will certainly be necessary if it doesn't allow for shifting that around...

I'll have to look around in the notes and see if I should design that circuit as well.

I still need to add the EEPROM terminals and ADC but real life has kept me busy the last few days.
Likewise I recently checked into fully populated boards since the IRMCK201 is so easily found in china and I think it'd cost about $200 for the entire controller section minus output stage already assembled... but I still really need to get started on the 300v-20v 3 output SMPS... will take longer to get working than the actual controller probably.


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## Evan (Feb 20, 2008)

Hi guys. Sorry I was absent for a while. 

Technologic - Wow you are really flying threw this thing. That is some good info from the IRF people. You know if we had an ultracapacitor bank we could use that pin to dump the regen power into it. That would be cool. However, we are going to have to look out for over charging the batteries. (ex. Person who recharges for a down hill drive) They saved you a lot of headaches buy having the regen current limitable. We need to talk more about how regen will be setup. 

Dennis - I have all my books mixed up because I also did (almost a second degree) in CET (computer engineering tech). I did not save all my books. The EET was 4 year but was really meant by the school to be done part time. I did not save all my text books but here are the ones I did. I wish I still had the books from my digital, physics and liberal arts electives.

The Art Of Electronics - Horowitz and Hill
Modern Operating Systems - Tanenbaum
Mechanics For Engineers (Statics) - Beer/Johnson
Unix For Programmers and Users - Gram Glass/King Ables
Assembly Language for Intel Based Computers - Irvine
C++ An Introduction to Data Structures - Nyhoff
Computer Systems Design and Architecture - Heuring/Jourdan
Advanced Unix Programming - Rochkind
Microelectric Circuits - Sedra/Smith (good ref. but Lousy teaching tool)
Matlab An Introduction with Applications - Amos Gilat
Introductory Circuit Analysis - Boylestad/Kousourou (10th edit)
C++ How to program - Deitel & Deitel (so so...)
A First Course In Differential Equations - Zill
Schaum's Outlines Differential Equations
Calculus (7th edition) - Larson Hosteler Edwards

Please note though that were I to be put in charge of the universe these would not be the books I would use to teach the classes I had. Prior to my time at NEU I was in a regular public highschool and before that I was homeschooled. There is a long story in there for some other time. In that time before NEU I studied electronics and other bits of science and engineering on my own. If you want I could list those books all of which I have kept in some other post. At this point though this should really be forked into another thread.

As for Technologic burning out a lot of stuff and quitting I doubt he will quite. It might take him/us 2 or 3 tries to get something that doesn't burn up though. I know an EE with 20 years in as a design engineer who shares my philosophy that nothing of any real complexity is ever done correctly in the first try.

samborambo - Don't mind my asking but you seem to know what you are talking about. What is your educational background? EE?


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## Technologic (Jul 20, 2008)

Ok here's the most up to date schematic... two things are still needed... a PSU (which I'm pouring over books now to organize a schematic on the best way to do this) and the analog input for throttle control.

http://img16.imageshack.us/img16/7905/part1l.png

The ramp must be perfectly linear to the input, so it'll either need to be done with a PI controller that changes the quadrature reference according to the sync input, or a straight closed loop control.

The PSU is nothing I need help on now... it's complicated, but I should have it finished in a few days.


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## JRP3 (Mar 7, 2008)

That attachment is too small to make anything out, even when I click on it.


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## Technologic (Jul 20, 2008)

JRP3 said:


> That attachment is too small to make anything out, even when I click on it.


take the link for the picture... it's 2900 x whatever resolution


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## Evan (Feb 20, 2008)

Yea I can't seem to get any use out of the thumbnails ether. Just use the link.


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## Mesuge (Mar 6, 2008)

samborambo said:


> This is the Microchip AN for advanced induction motor control with field weakening:
> 
> http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en536065
> 
> ...


Let me just bump up this interesting/worth pursuing proposal of using 
AN1206. Also that interesting link inside, there is an overview/AppNote of basic ACIM - sensorless field oriented control - field weakening:
http://ww1.microchip.com/downloads/en/AppNotes/01206A.pdf


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## Evan (Feb 20, 2008)

Mesuge - That is just the application note he already linked too? Technologic just want's to have something that works to test his output stage for now. I am unless I missed my guess the only one here looking at making an SVM implimentation and I am not going the uP route or for that matter interested in using microchips proprietary stuff. Why did you bump that document?

Edit: Also I don't think ether of us want to go the sensorless route.


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## Technologic (Jul 20, 2008)

Evan said:


> Mesuge - That is just the application note he already linked too? Technologic just want's to have something that works to test his output stage for now. I am unless I missed my guess the only one here looking at making an SVM implimentation and I am not going the uP route or for that matter interested in using microchips proprietary stuff. Why did you bump that document?


Well I sort of intend to make a working controller with SVM and sensorless options (since the MCK201 can do both)

At any rate right now I'm still reading about DC-DC converters... but the texts that are relevant are sparse and data has to be pulled from many sources . You either have cookbooks using low power ICs (common) or formula books that you need to go through and understand annoyingly easy concepts given in a difficult hard to understand manner to find useful information.

Who'd think a large format high voltage DC-DC buck converter is so uncommon? well at least for almost every writer of books it is. So uncommon they won't even mention it in passing.



> Edit: Also I don't think ether of us want to go the sensorless route.


I wouldn't if the code wasn't already in place... the current/voltage can be sensed via the Z channels + halls A/B/C if there's no encoder present.


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## Evan (Feb 20, 2008)

Look you know how a linear regulator works right? A zener diode is used to refrence the amount of power going threw a large power transistor from the source to the output. If you open up the spec for the LM7805 you will quickly realize how they made it. 

A switching regulator works almost nothing like a linear one. Switching regulators use PWM to charge some energy storage passive component (capacitor/inductor). The PWM duty cycle is decided by how much the output is sagging. So an unloaded DC/DC that has warmed up will have a duty cycle close to if not 0. They they use some filtering to smooth out the PWM noise as best they can.

edit : Err. I meant based on the voltage in. You want it over rated by a *lot* because over time it will wear down. I suggest using a capacitor instead of an inductor. I left out how you would go about filtering the design but I suspect that the oscillator will keep you busy for a while.

Size the capacitor/inductor to fit the power out. Then size it's voltage rating based on the depth of discharge required. Keep in mind the ESR if it is a capacitor. Now using the capacitors size find the PWM carrier frequency you want. (I guess you could start here and then size the cap/ind) Now make a fixed frequency PWM that adjusts it's duty cycle when the cap/ind charge is lower relative to some voltage refrence. You could use a zener but they make much better temperature compensated stuff now. 

The first one I ever made was just a few large caps charged with a darlington BJT a zener and an LM555 for PWM. The catch you have here is that most of the stuff you would use to build the oscillator has to be able to operate at 500V. Figure out how to make the PWM from your operating voltage and then build the rest of the system around that.


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## Technologic (Jul 20, 2008)

Evan said:


> edit : Err. I meant based on the voltage in. You want it over rated by a *lot* because over time it will wear down. I suggest using a capacitor instead of an inductor. I left out how you would go about filtering the design but I suspect that the oscillator will keep you busy for a while.


Oscillator ICs have made this a moot point to be honest.. I get the concept... that doesn't help me design one... and these books are pulling information out of a hat basically. I get the whole inductor, diode at ground, cap sizing, resistor sizing equations... however spices aren't turning out the results I want at 500khz of switching.



> Size the capacitor/inductor to fit the power out. Then size it's voltage rating based on the depth of discharge required. Keep in mind the ESR if it is a capacitor. Now using the capacitors size find the PWM carrier frequency you want. (I guess you could start here and then size the cap/ind) Now make a fixed frequency PWM that adjusts it's duty cycle when the cap/ind charge is lower relative to some voltage refrence. You could use a zener but they make much better temperature compensated stuff now.


You're talking about hystersis on the pwm? yeah that's what I've been trying to figure out wtf you do to get that voltage reference, however these books don't talk about it even once.
You need to keep in mind the inductors resistance too (DC resistance) but yeah a cap will work for that I suppose. 



> The first one I ever made was just a few large caps charged with a darlington BJT a zener and an LM555 for PWM. The catch you have here is that most of the stuff you would use to build the oscillator has to be able to operate at 500V. Figure out how to make the PWM from your operating voltage and then build the rest of the system around that.


I assume the PWM could be driven by an IC oscillator into the gate of a mosfet or IGBT to then pulse the output line? after that I could make 2 linear regulators of the raw line Vout to get the 5v and 3.3v I need for the low power components?
Perhaps a dual gated out oscillator, but the issue is feedback... WHERE do you put it... they don't make any ICs that do feedback past 100v in... so I'm stuck figuring this out in raw components. Apparently no books in the last 10 years even bother talking about doing this in the form of darlingtons etc because they just tell you about ICs instead...

Also, in the same realm as I was talking about before, I will need a linear regulator (or something) to take the 300v line to then power the oscillator as well without any input... which is just annoying if I made it this way.

You're talking about oscillating the 300v-500v from the start basically right? not through a gate? yeah that just doesn't sound like it'll be fun 

Edit: I've found a few different high voltage oscillators... so perhaps I can work with this.


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## Evan (Feb 20, 2008)

Technologic -

"Oscillator ICs have made this a moot point to be honest.. I get the concept... that doesn't help me design one... and these books are pulling information out of a hat basically. I get the whole inductor, diode at ground, cap sizing, resistor sizing equations... however spices aren't turning out the results I want at 500khz of switching."

You found an IC that can *run* *directly* off >=500V??!! Ok. Would you please show me a datasheet. Can I ask why you picked 500KHz? I mean I know it is common but what is the benifit *you* see of that specific carrier frequency?

"You need to keep in mind the inductors resistance too (DC resistance) but yeah a cap will work for that I suppose. "

ESR (Enitial Series Resistance) of a capacitor is an issue. Inductor resistance is less of an issue IMHO.

"You're talking about hystersis on the pwm?"

As for the PWM adding hysteresis to the PWM is not that big a deal. Though you are right to avoid noise at low frequencies you have to ensure that the duty cycle is always atleast a few % so the carrier is still comming out. Also you need a little hystersis to keep the entire DC/DC from self resonating. 

On a side note you should always include what we call a hickup mode. This is where the power supply after going over max. current shuts off for a second and then retests the output load. 

"yeah that's what I've been trying to figure out wtf you do to get that voltage reference, however these books don't talk about it even once."

As a voltage refrence you could just use a zener diode but they have better parts called voltage refrences (real imaginative name I know). These Voltage Refrences are basically just temperature compensated zener diodes. They typically have very low current ratings as they are meant to be *only* used for refrence and not for regulation unlike large zeners. Large zeners can be used (though poorly in my apprasal) for voltage regulation are not very efficent so we can forget about them. What book(s) are you using?? This isn't the kind of thing you can find directly in a book. For all intense purposes we are writting the cookbook because there is such a small market for these no one documents it. Look no offense but I can tell you have never done this before. Why don't you try building a simple one a breadboard first. 

I would consider using a MOSFET here over an IGBT. The sharpness of the edges is less important compared to the series resistance. Yes I guess you could just use two linear regulators, though I would go LDO (Low Dropout Regulators) for the logic stuff. The oscillator runs off the input voltage but it doesn't switch the power. It is better if you can for go putting a any regulator in after the DC/DC but I guess it wouldn't hurt to have the DC/DC make 5V and then use an LDO to get 3.3V for the IRF chip.

The power is switched by a large FET or IGBT. For our purposes a good size MOSFET will do just fine.


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## Technologic (Jul 20, 2008)

Evan said:


> You found an IC that can *run* *directly* off >=500V??!! Ok. Would you please show me a datasheet. Can I ask why you picked 500KHz? I mean I know it is common but what is the benifit *you* see of that specific carrier frequency?


I have... only one though I could find:
http://www.st.com/stonline/products/literature/ds/4946.htm
As far as picking 500khz the benefit is cap size IIRC... on the Vo... plus in general these would have lower efficiency losses.
Edit: Also you'd have less inductor losses the higher the frequency as the stored voltage/current wouldn't drop nearly as much.



> As for the PWM adding hysteresis to the PWM is not that big a deal. Though you are right to avoid noise at low frequencies you have to ensure that the duty cycle is always atleast a few % so the carrier is still comming out. Also you need a little hystersis to keep the entire DC/DC from self resonating.
> 
> On a side note you should always include what we call a hickup mode. This is where the power supply after going over max. current shuts off for a second and then retests the output load.


I was going to add this "hiccup" mode to the fault connections in the motor controller as well... however I hadn't researched the design parameters for reset... a timed relay should work ok in that case.



> "yeah that's what I've been trying to figure out wtf you do to get that voltage reference, however these books don't talk about it even once."
> 
> As a voltage refrence you could just use a zener diode but they have better parts called voltage refrences (real imaginative name I know). These Voltage Refrences are basically just temperature compensated zener diodes. They typically have very low current ratings as they are meant to be *only* used for refrence and not for regulation unlike large zeners. Large zeners can be used (though poorly in my apprasal) for voltage regulation are not very efficent so we can forget about them. What book(s) are you using?? This isn't the kind of thing you can find directly in a book. For all intense purposes we are writting the cookbook because there is such a small market for these no one documents it. Look no offense but I can tell you have never done this before. Why don't you try building a simple one a breadboard first.


No offense taken, I've never designed a PSU for a DC/DC supply like needed (especially one with this wide a gap). I never get upset when someone states the truth.

I can build a simple one... but I'm not sure what I'll learn by a simple one... the problem isn't understanding the concepts, I fully understand how this works fundamentally. The issue is finding any information on feedback... since it's clear to me this is necessary to keep the spikes smooth. And believe it or not nobody talks about it.

I've just finished _Pulse Width Modulated DC-DC converters_ by Keng C. Wu, and _Switch-mode power converters_ by Keng Wu also (chief engineer for Lockheed wrote them).
Both books were appallingly useless for this... which is just too funny to me. Spends 3 chapters just on math and wind up not learning anything useful.



> I would consider using a MOSFET here over an IGBT.


so would I... but IGBTs can't be beat for the price with low current here.



> The sharpness of the edges is less important compared to the series resistance. Yes I guess you could just use two linear regulators, though I would go LDO (Low Dropout Regulators) for the logic stuff. The oscillator runs off the input voltage but it doesn't switch the power. It is better if you can for go putting a any regulator in after the DC/DC but I guess it wouldn't hurt to have the DC/DC make 5V and then use an LDO to get 3.3V for the IRF chip.
> 
> The power is switched by a large FET or IGBT. For our purposes a good size MOSFET will do just fine.


Agreed... lemme see what I can do with what I know so far... 
after all of this and reading a lot of stuff about this I can't find any information on what exactly you're feeding back into the line to lower the voltage spikes even more after. they always just show a box and say "PWM sensing" or some bull shit... and I'm like ooooooooooooooooook wtf is in that Opamp? or IC or w/e

My gut is telling me that it's feeding back in order to continue to smooth the wave form through the inductor/cap etc, but again that doesn't make a lot of sense either since a lot of these feedbacks are going directly to the IC. I'll never understand how someone can go through the trouble writing huge articles and books and yet think it's ok to make boxes for circuits and go "PWM voltage sensing" and never talk about it etc. But it's all over the place.


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## Technologic (Jul 20, 2008)

after messing around with reading this again:
http://services.eng.uts.edu.au/~venkat/pe_html/ch07s1/ch07s1p1.htm#closed_loop

I somewhat understand that doing a higher amperage circuit (car accessories) will require a bit of coding to be done if you want an efficient waveform (well changing the duty cycle will sure be easier with a PI controller).

hmph


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## Evan (Feb 20, 2008)

That is an odd chip you found. It is meant for low power lighting applications which use very high switching frequencies. Using higher carrier frequencies causes more loss in the big capacitor you are using. I think going lower in frequency would be to your advantage but I could be wrong. I was actually thinking that it might be nice to use a step down transformer in the DC/DC but I will explore that on my own, the additional weight and EM might be an annoyance. 

Typically Hiccup mode (thanks for the spelling correction) doesn't power the unit totally back on after it is tripped. This saves the power transistors wear.

"I can build a simple one... but I'm not sure what I'll learn by a simple one... the problem isn't understanding the concepts, I fully understand how this works fundamentally."

Ex. Just try to make 6V (4xAA) to 3.3V. Then try to do it with out an oscillator chip.

"The issue is finding any information on feedback... since it's clear to me this is necessary to keep the spikes smooth. And believe it or not nobody talks about it."

This tells me you need to make the simple one first. Seeing it work and more importantly seeing it not work will teach you a lot. For example the reason to get the spikes smooth is to keep noise down. Keeping a constant carrier frequency is important because it means your output filter will be at it's optimal effectiveness. The output filter is typically just a butterworth lowpass filter. 

The feedback is only as complex as you choose to make it. Just put a zener with a resistor and have the PWM duty cycle shift as the voltage grows to the proper level.

"after messing around with reading this again:http://services.eng.uts.edu.au/~venk...tm#closed_loop"

You are getting what I would call excessively thoeretical. Look this is not a very complex problem. Yes you can shoot for the very complicated things like PI stuff but the efficency gains are in this case I suspect nominal. This is where making that first DC/DC converter would help you. It would show you how simple this kind of problem can be if you let it. Less reading and more doing. Even if what you are building isn't what you need really it will still make it all more farmilliar. I know everyone is on the uP in everything train but this is one case where I don't see it helping enough to make the design time worth it.

Edit: I am considering using an SCR instead of IGBT or MOSFET.


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## Technologic (Jul 20, 2008)

Evan said:


> This tells me you need to make the simple one first. Seeing it work and more importantly seeing it not work will teach you a lot. For example the reason to get the spikes smooth is to keep noise down. Keeping a constant carrier frequency is important because it means your output filter will be at it's optimal effectiveness. The output filter is typically just a butterworth lowpass filter.
> 
> The feedback is only as complex as you choose to make it. Just put a zener with a resistor and have the PWM duty cycle shift as the voltage grows to the proper level.


I know why to keep the spikes down (and all the reasons for a soft start etc).

However as soon as you said a zener and resistor it hit me what it's for... 

I'll try to work up something here... that feeds back into the duty cycle to lower it the less resistance it sees on the outputs. Cheers

I'd normally make something just to make sure I'm making it correctly, however, since my ICE broke down 2 weeks ago not really able to run around like I'm usually free to do


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## Evan (Feb 20, 2008)

Ahh Now you are on the correct track. An optical isolator can solve some of the issues too.


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## Technologic (Jul 20, 2008)

Evan said:


> Ahh Now you are on the correct track. An optical isolator can solve some of the issues too.



I found this paper:
http://www.priorartdatabase.com/IPCOM/000007248/

And I finally get it 
It's very simple, just needed it at least written to understand what was going on.

"The mean voltage ofa logical signal is ratiometric
to its duty cycle. For a square wave signal between
OV and Vh with a duty cycle th/t the mean voltage
is defined as: V mean = Vh x th/T. In this condition
a 50% duty cycle is characterized by a mean voltage
Ofv,,,,= V5O=Vh/2.
From a technical point of view the mean voltage
is measured with an integrator (Low pass filter R-C).


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## Evan (Feb 20, 2008)

That is still more complex than this has to be but if you understand it by all means. You know in the hours you seem to spend googling for papers you could have just tried to reason threw this. If you really want to advance the state of the art you can't do so by just redoing something.


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## Technologic (Jul 20, 2008)

Evan said:


> That is still more complex than this has to be but if you understand it by all means. You know in the hours you seem to spend googling for papers you could have just tried to reason threw this. If you really want to advance the state of the art you can't do so by just redoing something.


I have tried to reason through it  for whatever reason I just couldn't get past the whole comparator to reference voltage to match the duty cycle thing. 

I realize now again, how complicated I make things  I'm self taught so I guess I need to fill in gaps from the top down sometimes.


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## Evan (Feb 20, 2008)

The simplest thing to do is this.

Edit : The diode I drew in ASCII down there is a zener but because this is HTML formatted it wouldn't accept it. Just pretend the little diagonal lines are there on the cathode end.

Vout----|<|----/\/\/\----GND

So power out gows threw the zener (rev. breakdown 5V) and resistor. The resistor keeps the zener with say a 100uA of backward current. This means that if the power goes over 5V you should see a little bit of voltage across the resistor. This feedback voltage is what I used in my first simple DC/DC to control pulse width.


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## Technologic (Jul 20, 2008)

Evan said:


> The simplest thing to do is this.
> 
> Edit : The diode I drew in ASCII down there is a zener but because this is HTML formatted it wouldn't accept it. Just pretend the little diagonal lines are there on the cathode end.
> 
> ...


Right so this is effectively a pull down resistor that's only on when the zener breaksdown. However, this would wear the diode out pretty fast no?
I was looking into an integrator, differentiator, comparator loop that normalized it against a shifting reference (ie. a reference that changes with the load seen) which would effectively 0 our the duty cycle (nearly) when no load is present.

If I understand that, it'd work just fine to shift duty cycle and normalize it that way.


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## Evan (Feb 20, 2008)

"Right so this is effectively a pull down resistor that's only on when the zener breaksdown. However, this would wear the diode out pretty fast no?"

Ahem... This is what zener diodes were meant for. The diode will survive as long as the current is kept in the rated range. 

Edit: look at the series regulator here. http://en.wikipedia.org/wiki/Linear_regulator

"I was looking into an integrator, differentiator loop that normalized it against a shifting reference (ie. a reference that changes with the load seen) which would effectively 0 our the duty cycle (nearly) when no load is present."

Ah. That is kind of how the LM555 works. It uses and integrator to make a ramp. A comparitor then triggers when the voltage is above a given voltage from a series resistor voltage divider. There is a flip/flop to toggle an analog switch to discharge integrator making a down ramp that again is compared and well you get the idea. 

Have you found any comparitors and amplifiers you can run of 500V directly??


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## Evan (Feb 20, 2008)

The dangers of learning from research papers are numerous. The most obvious fault is that they are often unintentionally wrong. It is research after all and being so new is not completely known. But the other drawback is that typically you want a basic explination of something and those papers are about expaining some new addition to it not the thing itself. Finally they are written by people trying to be impressive and that tends to make them less clear as the authors try to make their work sound more complex. I learned all most all of this on my own by tinkering trying to make one small project after another. As I said I was home schooled for many years.

Of all the books I have read the few I hang on to are these.

Getting Started In Electronics - Forrest M. Mimms III
The Art of Electronics - Horowitz and Hill (among EE's this is nicknamed "The bible")
The ARRL Handbook - numerous (I think you need this. It doesn't have to be the current edition.)
The Best of Ciarcia's Circuit Cellar - Ciarcia
Mobile Robots - Jones, Seiger and Flynn
The Robot Builders Bonnanza - Gordon McComb
Linux Programming by Example - Wall


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## Technologic (Jul 20, 2008)

Evan said:


> Have you found any comparitors and amplifiers you can run of 500V directly??


You wouldn't have to would you? You could just use a oscillator that's rated for it... (with a voltage clamp like that IC I posted before had)

Here's the image of what I'm talking about:



Obviously this isn't ALL of the parts, I drew it in 2 minutes (there'd be another opamp in there as well and the same setup for the high side gate). however you get the general idea. It's pulling the already "processed" line voltage back for comparison correct?

That IC is just a random IC... think of O1 as the High output and O2 as the low output.


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## Evan (Feb 20, 2008)

That won't work. I have to get some rest I will explain it again or possibly just do it on my own later. I don't know what timezone you are it but it is 3AM here.


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## Technologic (Jul 20, 2008)

Evan said:


> Getting Started In Electronics - Forrest M. Mimms III
> The Art of Electronics - Horowitz and Hill (among EE's this is nicknamed "The bible")
> The ARRL Handbook - numerous (I think you need this. It doesn't have to be the current edition.)
> The Best of Ciarcia's Circuit Cellar - Ciarcia
> ...


I should get that Art of electronics book... thanks


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## Technologic (Jul 20, 2008)

Evan said:


> That won't work. I have to get some rest I will explain it again or possibly just do it on my own later. I don't know what timezone you are it but it is 3AM here.


Well there'd need to be two integrators in line after the comparators... it might be too late for me to think of what I'm attempting to explain... but that's the vibe that paper was giving about correction of the duty cycle based upon the output voltage being matched against a reference then integrated into a DC signal then back into the input of the gate to normalize the error out.

I'll draw a better explanation later... with the 4 op amps needed for each gate.

I THOUGHT I understood it... if that's not how it works *grrrrr* If you can point me to a book I will be more than happy to find this information out myself to save you any time. I thought you could do the duty cycle computation that way... seemed like a good way since the first Vref could be lowered to 0v and end the entire loop cycle thereby dropping error adjustment to zero which could trigger a 0 duty circuit.


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## Technologic (Jul 20, 2008)

Here's a more filled in schematic of what I was talking about last night. The integrated waveform out is compared to the vref giving an error PWM signal. This error signal is fed into a differentiation circuit that then turns it into a steady state voltage... that is used as a vref for comparision to the PWM which outputs a "corrected" voltage shift (according to the error voltage reference).

http://img11.imageshack.us/my.php?image=examplea.png


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## Evan (Feb 20, 2008)

You are going even further off the map. I took a deeper look into that L6569 chip and it just is not going to work here. The chip has the internal components needed to almost with out any other semi's be a switching regulator but it is not a good one and it's intended output voltage and current are radically different than what you want. 

Just stop and give me some time and I will work something out.


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## Technologic (Jul 20, 2008)

Evan said:


> You are going even further off the map. I took a deeper look into that L6569 chip and it just is not going to work here. The chip has the internal components needed to almost with out any other semi's be a switching regulator but it is not a good one and it's intended output voltage and current are radically different than what you want.
> 
> Just stop and give me some time and I will work something out.


I was more concerned about the feedback adjustments  I hadn't decided if I was going to need to build a switching regulator for the gate(s) or not.

At any rate feel free.


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## Evan (Feb 20, 2008)

You need the ARRL Handbook. If you want the art of electronics by all means get a copy but also grab the student manual that goes with it and the labs in it. You seem to have the basic ideas of circuit analysis down for linear stuff. The problem is that this is a design concept problem and there just isn't a book(s) that can be a how-to on design.

If you are really determined to learn this just try to do what I suggested and make a simple DC/DC converter to get 3.3V from 6V. It is simple, cheap and safer than playing with 500V.


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## JonasMeyer (Feb 28, 2009)

This comment is a bit away from where the conversation has drifted, but I feel it is important to give my input.

The limiting factor on power output for this controller is NOT going to be the rating of the components. It is going to be our ability to cool those components. Therefore, any component which has even a small voltage drop at high amperage should be kept away from other such components. Therefore 6 packs or even 2 packs of IGBTs are bad ideas except in a proof of concept design. Use singles so we can give them the maximum cooling possible.


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## Evan (Feb 20, 2008)

Dude I made that SAME comment way way way back. We are off the IGBT module vs seperate debate. We are I think are both using 3 * double modules. The cooling thing is gone for the moment. We are working out DC to DC converters now because we are going to need one to power the inverter. I have some ideas about limiting EMI propogation while providing more even cooling but that is for a later time.

Incidentally if Technologic choose to go with some kind of liquid cooling, which I would advise against, it would be ok to go with more integrated modules.

At this point the limiting factor is unknown. It could be the chips SVM algorithm's precision, it could be the heat, it could be the IGBT speed or other ratings. We don't know and likely can't for a while. There are so many unknowns.


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## Evan (Feb 20, 2008)

Sorry about being so short with you guys earlier. 

Technologic - The following two links are good explinations of what I am getting at. They are by no means ideal solutions to these problems but they would be things I think you could do.
http://www.seanet.com/~karllunt/junkbox.htm
Junk Box Switcher is a great example of a step down switching regulator.
http://en.wikipedia.org/wiki/Buck_converter
This is the explination of the basic principal it uses.


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## aeroscott (Jan 5, 2008)

Evan , can you expand on you thoughts on liquid cooling .


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## Technologic (Jul 20, 2008)

Here's an example of what kind of "PWM signal" generator I was thinking about (threw this together really fast).
Since this is a low level sawtooth generator it could be used to generate PWM through ICs etc. 

It draws roughly 2.5mA and appears to output (though I can't check 100%) something like 90mA average at 15v regulated. Which would of course make it about 12% efficient, but only draw 1.25w. So... using a discrete option for the input to the switching mosfets seems like a decently low power option (at least once coupled to a high efficiency SMPS). 
It's not ideal of course, but workable.

If you got 90% efficiency out of making 20vx10a (200w) + 12% efficiency at 1 watt, it would average out ok.

There's a few ways to soft start this changing C2 is one way.


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## Evan (Feb 20, 2008)

Technologic - I was just throwing that out there so you could see how simple one of these could be. It is not by any means what you have to use as a starting point. Yes I know it is not efficenent. Also the transistors you used 2N3906's won't take that kind of power any way unless I am mistaken. 

Airoscott - I know there are on both EVDL and other places an ongoing flameware over this. The way I see it is this, if the weight of a largenough heatsink trumps the weight and energy required to run a pump and smaller heatsink it is good. This is obvious. However, there are some heat distrobution problems that are best solved with water. Motor cooling is much more effective with water than air. The question is does it improve motor efficency enough to deal with the loss of running the pump? Cooling semiconductors is not that intersting at least to me. I would rather cool them with a fan. If you are clever I guess you could do a way with the fan and have the heatsink stick up threw the hood. You would need a thermally reliable gasket around it of course. Unless you were drag racing, where more of the heat is released when starting that would in my guestimation ok. Though I am a range nut and every one else here seems to care more about raw power. I guess they might go water cooling. 

In ether event that is a more advanced issue than what we are talking about right now. I guess we should address it though. Technologic should take a carefull look at the thermal resistance of the case those IGBT's he is using will cost.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - I was just throwing that out there so you could see how simple one of these could be. It is not by any means what you have to use as a starting point. Yes I know it is not efficenent. Also the transistors you used 2N3906's won't take that kind of power any way unless I am mistaken.


There's lots of ways to do it... the 2N3906's were used as an example since that program does not have many options to choose from.
I made that as an example of what you could feed into an opamp for then PWM signal generation... and nice the wave form is so easy to adjust when no load (duty cycle shift via raising the effective R1) it's pretty simple.



> In ether event that is a more advanced issue than what we are talking about right now. I guess we should address it though. Technologic should take a carefull look at the thermal resistance of the case those IGBT's he is using will cost.


Yeah I'll be looking at it latter, once I actually decide which IGBTs I'm going to use


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## coulombKid (Jan 10, 2009)

etischer said:


> I don't think it is possibe to get 100% torque at zero speed without vector mode.
> 
> Think of it this way, at 100% speed you are supplying 230vac at 60hz. At half speed 120vac at 30hz. At 1% speed 2.3vac at 0.6hz. you can't expect 100% torque when supplying the motor 2.3 volts. You can put some DC boost in there, but I don't think you can get close to the performace as a true vector setup.
> 
> You can do sensor-less vector mode which does not use an encoder, it just needs current feedback.


Most AC industrial 3-phase motors kick out big torque numbers from a standing start with a standard across the line motor starter at 60 hz. The motors are, in general, most efficient running at 60 hz. With control of frequency, and of current (through PWM modification) it is possible to limit torque and current in-rush to values within the operational envelope of the mechanical drive line and the electrical and thermal limits of the vector drive. I'm not looking forward to the volume of data collection and tests needed to get the bugs out. I suspect the vehicle needs to be built to run at 60 hz when at the average cruise speed for maximum range. When passing 90 hz would not be an unreasonable expection.


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## coulombKid (Jan 10, 2009)

Greenflight said:


> I don't think this exactly how v/hz works. It is not related to the actual speed of the motor, just the position of the throttle sensor. So, assuming you had a minimal acceleration curve, you could be supplying 230vac to the motor at 60hz and the motor could still not be turning.
> 
> Vector mode essentially uses a measurement of motor RPM to adjust the v/hz ratio to account for variations cause by load.
> 
> That's why v/hz isn't so awesome for applications involving load.


If in fact your RMS voltage was 230 at 60 hz in a zero rotor speed, current would be many times the FLA rating of the motor. The higher the NEMA letter code the higher the starting current multiplier. The lower the NEMA code letter the better the range and the lousier the off the line performance. A true RMS voltage feed back, as well as both current vectors would be essential to the calculations for the PWM routine. For v/hz I imagine you only need RMS current and voltage feed back. To resolve the current signal into its magnetizing and torque vectors we have to have true rotor angular velocity to calculate the slip angle. True rotor position in this application should not be necessary. In a direct drive EV the speedometer reading compared the the current electrical drive frequency being generated gives a direct value proportional to the slip angle being generated in the rotor. The tuning necessary by commercial drive producers for a given motor in a given car involves getting a linear relationship between your right foot and the torque felt. Thats an awful lot of data loaded into look-up tables.


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## Evan (Feb 20, 2008)

Technologic - I am trapped a few towns away from my computer right now so my work on the DC/DC converter is a no go at the moment. I was driving back on the highway last night and the cars fuel pump died. 

In any event I suspect that many of he IGBT's have similar if not identical footprints. I wonder if we might be able to make a layout that works across a few different choices? Just a though for after we get something running.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - I am trapped a few towns away from my computer right now so my work on the DC/DC converter is a no go at the moment. I was driving back on the highway last night and the cars fuel pump died.


Don't you just hate ICEs?


> In any event I suspect that many of he IGBT's have similar if not identical footprints. I wonder if we might be able to make a layout that works across a few different choices? Just a though for after we get something running.


Yeah this is my exact thoughts. Bridge IGBTs generally have the same footprint... at least Powerex and Fuji do.

I have a pretty good idea how to make the DC/DC converter work off a high voltage setting... though it won't be completely efficient (maybe 80%) it'll work well enough and be cheap.


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## aeroscott (Jan 5, 2008)

I just found a 400 volt variable speed motor controller . could this become a 400v to 12 v converter . Vectron , 3x400 v 50/60 hz 3.8kva, 3x0-400 v 5A 2.2kw 0-1000 hz


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## Evan (Feb 20, 2008)

aeroscott - I am working on something that will be significantly better than the thing I inadvertently lead Technologic too.


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## Dennis (Feb 25, 2008)

I decided to go out on a limb for you Technologic, to keep this project rolling since the DC-DC converter seems to be the stumbling block. I have spent my time reverse engineering a switching power supply that accepts 120Vrms AC and outputs 5 volts DC @ 1 amp and 3.3 volts DC at 6 amps. I have drawn up a schematic in MS-paint for you to study how an isolated DC-DC converter is made. A switching power supply is nothing more than a DC-DC converter with AC conditioning circuits for filtering and coverting the AC to DC. Here is the schematic I came up with from my reverse engineering analysis:



http://img16.imageshack.us/img16/5752/revpsu.jpg






Components:

R1=12Kohm, 5%, metal oxide, 3W
R2=0.51ohm, 5%, wirewound, 2W
R3=820Kohm, 5%, carbon film, .250W
R4=22ohm, 5%, carbon film, .250W
R5=10Kohm, 5%, carbon film, .250W
R6=22ohm, 5%, carbon film, .250W
R7=150ohm, 5%, carbon film, .250W
R8=1Mohm, 5%, carbon film, .250W
R9=150Kohm, 5%, metal oxide, 1W
R10=1Kohm, 1%, metal film, .250W
R11=5.1Kohm, 1%, metal film, .250W
R12=5.1Kohm, 1%, metal film, .250W
R13=1Kohm, 1%, metal film, .250W
R14=10ohm, 5%, carbon film, .500W
R15=10ohm, 5%, carbon film, .500W
R16=100ohm, 1%, metal film, .250W
R17=1Kohm, 1%, metal film, .250W
R18=2.2Kohm, 1%, metal film, .250W
R19=374ohm, 1%, metal film, .250W
R20=1Kohm, 1%, metal film, .250W
R21=100ohm, 5%. carbon film, .250W

PTC1=7ohm at room temperature thermistor for current inrush limit

L1=10uH
L2=Unknown

T1=Unknown transformer

C1=.1uF, metallized polyfilm, 250V, 10%
C2=470pF, ceramic, 1Kv, 10%
C3=2200pF, ceramic, 400v, 20%
C4=.22uF, metallized polyfilm, 275v, 10%
C5=47uF, electrolytic, 50v, 20%
C6=470pF, metallized polyfilm, 50V, 2%
C7=150pF, metallized polyfilm, 50V, 2%
C8=.018uF, metallized polyfilm, 50v, 2%
C9=.1uF, ceramic, 50V, 20%
C10=.01uF, metallized polyfilm, 50v, 2%
C11=.0022uF, mica, 50v, 5%
C12=2200uF, electrolytic, 10v, 20%, Low ESR
C13=2200uF, electrolytic, 10v, 20%, Low ESR
C14=1000uF, electrolytic, 10v, 20%, Low ESR
C15=2200pF, ceramic, 400v, 20%
C16=1000uF, electrolytic, 10v, 20%, Low ESR
C17=470uF, electrolytic, 10v, 20%, Low ESR
C18=.22uF, metallized polyfilm, 50v, 2%
C19=.01uF, metallized polyfilm, 50V, 2%

ZD1=MAZS039GHL 4v zener diode

D1=UF108
D2=UF102
D3=YG802C04

Q1=SK2645 N-Channel Mosfet

SCR1=MCR100

U1=UC3842 main PWM chip
U2=7805 linear regulator
U3=PC817 opto coupler
U4=TL431 shunt used as integrator due to built in op amp.

I omitted a 68uF main filter capacitor, dual line choke, one 2200pF cap, and the full wave bridge rectifier as those where for AC and thus I left those out since it will be powered by DC. This DC-DC converter will work well with 170VDC. If you want to run higher voltages then you must change out the mosfet, R9 resistor, transformer, PTC, and some caps that are exposed to high mains DC voltage...

There may be some errors, but I triple checked to make sure I got it right. So it should be ready to go!


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## Technologic (Jul 20, 2008)

Dennis said:


> I omitted a 68uF main filter capacitor, dual line choke, one 2200pF cap, and the full wave bridge rectifier as those where for AC and thus I left those out since it will be powered by DC. This DC-DC converter will work well with 170VDC. If you want to run higher voltages then you must change out the mosfet, R9 resistor, transformer, PTC, and some caps that are exposed to high mains DC voltage...
> 
> There may be some errors, but I triple checked to make sure I got it right. So it should be ready to go!


Pretty simple... thanks for the information.
It seems the more I read the more people are using Chip's for PWM generation/control and either triac filters (easy) or thermosisters for soft start.

I have some good ideas... but I'm hoping nothing that complicated is needed. Perhaps it will be, but I have a good idea of how to solve this issue with a bit of cheap planning. 

It appears these people are pulling the lower references and DC supplies to power the chips straight from either voltage dividing resistors or zener clamps... which makes the job much easier.

I appreciate the work... just give me a few days to have time to work on this some more... I'll have time later this week after some of my papers are finished.


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## Dennis (Feb 25, 2008)

> It appears these people are pulling the lower references and DC supplies to power the chips straight from either voltage dividing resistors or zener clamps... which makes the job much easier.


Yes, the UC3842 has a zener built in, but that is for limiting the voltage when it is "bump" started. What I mean is initially the chip cannot get its power from the transformer since it does the job of producing the squarewave pulse width signal which is needed to induce a voltage in the transformer coils (Faraday's law of changing magnetic fields). So mains DC voltage is applied via R9 resistor which limits the current to a low value. Once the chip is able to start up, the power then comes from that transformer coil you see with D2, L1, R4, and C5 parts that condition and convert the AC to DC to power the UC3842.


If you mean ZD1 then that is not what it seems. That is part of an over voltage protection for the 3.3V rail that will trigger the SCR latch if the 3.3 volt rail reaches 4 volts which pulls down the output of the TL431 and thus shuts down the power supply.

Have fun! You got something to go with now.


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## Evan (Feb 20, 2008)

LOL That is like what I am doing only I was going for push pull.

Technologic - Thermistors are frowned on for starting reasons because the powersupplies temperature drifts as it warms up and as the rooms ambient temp changes.


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## Technologic (Jul 20, 2008)

Evan said:


> LOL That is like what I am doing only I was going for push pull.
> 
> Technologic - Thermistors are frowned on for starting reasons because the powersupplies temperature drifts as it warms up and as the rooms ambient temp changes.


Agreed... however the one Dennis linked used that as a soft start... I have some ideas how to soft start 500v anyway.

http://www.brannonelectronics.com/images/DCtoDC.pdf

Push-pull is fine and all I just don't know if you'll get more out of it than a switch mode PSU...

Maybe the output stage will be cheaper though.


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## Evan (Feb 20, 2008)

Technologic - Look at the application note for the chip that design used. 
www.nxp.com/acrobat_download/applicationnotes/AN1272.pdf
That converter is a flyback design (notice the dots the windings).

The thing I am still going to work on is going to use a more common step down transformer. That thing you showed is like what I am doing only it is step up. This is of course going to be heavier than if we used a capacitor for sloshing the power around but it is more efficent and likely more reliable. Oh while we are talking about that like notice R5 and R6 being used to damp the potential resonance of the output filter. This reduces it's filtering ability but is generally a good idea. They won't let you do it in military or space work though. Also because that has no feedback it will basically only be as efficent a linear supply. I guess this is good for driving our electronics which are a basically constant load but if you were to do the car stuff (lights, wipers & etc) I would try to do better.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - Look at the application note for the chip that design used.
> www.nxp.com/acrobat_download/applicationnotes/AN1272.pdf
> That converter is a flyback design (notice the dots the windings).
> 
> The thing I am still going to work on is going to use a more common step down transformer. That thing you showed is like what I am doing only it is step up. This is of course going to be heavier than if we used a capacitor for sloshing the power around but it is more efficent and likely more reliable.


You're talking about using a cap as the output inductors? It will be more expensive as well if so... 

At any rate that chip is fine being up to 180v and only 1mA.

There are other ways to get 80+% efficiency with/without discrete options.


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## Evan (Feb 20, 2008)

"You're talking about using a cap as the output inductors? It will be more expensive as well if so... "

No. Look in a while I will have a diagram to show you. Not that I am agains't using special function chips but I am currently avoiding them. This should save us from supply issues later. I don't want to end up designing something I can't order the parts for with out buying 1000 or that is dependant on a discontinued part.


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## Evan (Feb 20, 2008)

Technologic - What voltages do we need out again. I know we need 5V and 3.3V but don't we need like 20 or something funny for your IGBTs?


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - What voltages do we need out again. I know we need 5V and 3.3V but don't we need like 20 or something funny for your IGBTs?


20v x 2A-3A, 5v and 3.3v...


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## coulombKid (Jan 10, 2009)

Technologic said:


> 20v x 2A-3A, 5v and 3.3v...


From the data sheets I've gone through the voltage to turn them on hard is usually 15 to 20 but the bad news is that the voltage needed to hold then off is about -10. If you don't the IGBT can turn it self back on creating a dead short for the batteries.


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## Evan (Feb 20, 2008)

Ok so we really need +20V, +5V, +3.3V & -10V. I wish that -10V was -20V.


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## Technologic (Jul 20, 2008)

coulombKid said:


> From the data sheets I've gone through the voltage to turn them on hard is usually 15 to 20 but the bad news is that the voltage needed to hold then off is about -10. If you don't the IGBT can turn it self back on creating a dead short for the batteries.


.... would you mind pointing me to this?

I've read the IR2133 data sheet and it does not say anything about needing a negative gate bias.

http://www.irf.com/product-info/datasheets/data/ir2133.pdf

Or are you talking about the IGBT's datasheet? because if so I don't intend to use powerex.

Fuji or Mitsubishi actually.... if so that will suck bad as I originally asked if the IGBTs needed a negative bias. 

I've gotten prices for dual drivers:
http://www.fujisemiconductor.com/pdf/B0401275.pdf

That were $95 from china... so I figured that'd be the best option.
If that's the case it's not an easy fix at least I don't believe so... the IR2133 gate out I believe only drops down to ground... and it can't be a -10v ground either. that will require a discrete negative bias gate circuit affixed only to the emitter via a cap or something.

I'd also want to double check a -20v can't be used as that would be straightforward and inherent in the ground supply design.


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## Evan (Feb 20, 2008)

Technologic - Are you sure that you can connect that gate driver part to the IRMK part? The gate driver uses 2.5V logic and the IRMK is unless I am mistaken 3.3V. I do not know about the -10V that might be relative to the 250V midpoint we use between 0V and 500V.

coulombkid - In regards to what you said in the old thread. The IGBT's are the most expensive single component. However the tooling costs for a company to produce these would be high. We are talking about a custom metal case with multiple compartments, stamped copper plates or cut bars preferably nickle plated and the list goes on. The intilectual property is probably not that expensive.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic - Are you sure that you can connect that gate driver part to the IRMK part? The gate driver uses 2.5V logic and the IRMK is unless I am mistaken 3.3V. I do not know about the -10V that might be relative to the 250V midpoint we use between 0V and 500V.


The gate driver accepts 5v logic.
Also the logic outputs on the MCK201 are already 5v I believe.

These are the recommended settings:
VIN Logic input voltage (HIN, LIN, ITRIP, SD & FLT-CLR) VSS VSS + 5
Vss would be 0 under most circumstances so the recommended setting is a 5v logic input.

I suppose they would be about 2.5v logic, but it's set to allow for up to 5.2v before clamping it off...

The options on the output stage are very limited otherwise...


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## Dennis (Feb 25, 2008)

> The thing I am still going to work on is going to use a more common step down transformer. That thing you showed is like what I am doing only it is step up. This is of course going to be heavier than if we used a capacitor for sloshing the power around but it is more efficent and likely more reliable. Oh while we are talking about that like notice R5 and R6 being used to damp the potential resonance of the output filter. This reduces it's filtering ability but is generally a good idea. They won't let you do it in military or space work though. Also because that has no feedback it will basically only be as efficent a linear supply. I guess this is good for driving our electronics which are a basically constant load but if you were to do the car stuff (lights, wipers & etc) I would try to do better.



Evan, R6 resistor of the circuit diagram is a gate resistor for the MOSFET. Unless you were talking about something else, then sorry. Also the circuit DOES have feedback. Did you not see the optocoupler? Again if you where not talking about the schematic I posted, then sorry. 


Technologic, I do not think you must have read my post. So I shall tell you again. The UC3842 chip you see in that schematic is not powered by mains DC. It is only started up initially by mains DC by the current limiting resistor R9 connected to the mains DC. Once powered up the transformer coil that has components D2, R4, L1 connected to it then connected to the chip's Vcc pin provides the power. You can start up the chip on higher voltages provided that resistor R9 is of higher value to limit the current to same amount as was before for the lower voltage.


If any of you want to know the name of the PSU that I reversed engineered then shoot my a PM. I don't think it would be wise for me to disclose the company that made the powersupply or the model number on this public forum. After all, reverse engineering is not exactly legal or is it?

So you need 20 volts too? I can reverse engineer a switching power supply used for ******* ******* printers. It's at 18 volts though and 1.1 amp, but you can adjust the output voltage by changing some resistors that form the reference to get the psu to ouput higher voltage.


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## samborambo (Aug 27, 2008)

You don't need 20V. Most IGBTs have a Vge saturation voltage of around 6V. This is the point where the device is fully on. A 100% fudge factor is suitable for most devices' temperature and current ranges. Most datasheets specify the IGBT turn on times with Vge=12V.

Negative gate bias is desirable but not necessary as long as the device is not switching to hard. A condition known as emitter "latch-up" can occur with particular devices switching high currents at high dv/dt gate pulses. The latch up will cause a fault current when the other half of the leg turns on - probably destroying the devices. Selecting the appropriate gate resistors for turn on and turn off should eliminate this risk.

So you don't need a negative rail and the gate drive rail only needs 12V. Your after a flyback power supply capable of handling 400V input and output 12V, 5V and 3.3V at fairly meager currents. Hmmm.....what kind of off-the-shelf power supply could possibly fit the bill?

(hint: add an ATX power conector to your PCB)


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## Technologic (Jul 20, 2008)

samborambo said:


> So you don't need a negative rail and the gate drive rail only needs 12V. Your after a flyback power supply capable of handling 400V input and output 12V, 5V and 3.3V at fairly meager currents. Hmmm.....what kind of off-the-shelf power supply could possibly fit the bill?
> 
> (hint: add an ATX power conector to your PCB)


It's possible to drop it down to 15v or even 12v for a tad better response curve overall... since many of the bridge drivers don't require much above that to function at peak efficiency.

Response voltage is max 8v for on usually... so you are correct...



> Technologic, I do not think you must have read my post. So I shall tell you again. The UC3842 chip you see in that schematic is not powered by mains DC. It is only started up initially by mains DC by the current limiting resistor R9 connected to the mains DC. Once powered up the transformer coil that has components D2, R4, L1 connected to it then connected to the chip's Vcc pin provides the power.


No I got that part, that's just not exactly useable for a DC/DC converter... the mosfet parts to output stages are though.


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## Evan (Feb 20, 2008)

Dennis - I was talking about the schematic Technologic posted sorry about the confusion. I really don't want to get involved in anyones reverse engineering stuff. I like being employable. 

samborambo - Good point about the ATX power connector for bench testing. 

Technologic - The flyback circuit is cool don't ge me wrong but winding our own flyback is not going to be fun.


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## Technologic (Jul 20, 2008)

I've found the output stage of choice no doubt about it... I didn't even know they made it till recently.

It's perfect (actually a bit beyond perfect) and for the low low price of $200/1qty 

450A at room temp continuous... and 6 channels

6MBI300U-120
http://www.fujisemiconductor.com/pdf/B0401510.pdf

Gotta love Fuji electric  Dead sexy. Makes the output stage cost less than the Zilla's single IGBT. Freaking thing will cost maybe $400 in parts (including PCBs) now.


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## samborambo (Aug 27, 2008)

Technologic said:


> I've found the output stage of choice no doubt about it... I didn't even know they made it till recently.
> 
> It's perfect (actually a bit beyond perfect) and for the low low price of $200/1qty
> 
> ...


Not quite perfect. This has an input capacitance of 34nF and recommends a 2ohm gate resistor. That requires a gate driver capable of at least 7.5A pulse current! Either shop around for a device with a lower input capacitance or design a beefier gate drive. Microchip has low side 9A gate drivers, otherwise I can help you design a totem pole current amplifier gate drive.

The on state voltage for this device is fairly respectable. There's always a trade off between Cies (input cap), Vce(max) and Ic. The input capacitance is probably the best you'll get for a device of this spec. Do you really need all that power? Start off small - otherwise you're gonna have to start designing active snubbers, isolated gate drives, etc. Plus, for a prototype, you don't want to piss away $200 on an IGBT bridge every time you make a mistake 

Sam.


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## Technologic (Jul 20, 2008)

samborambo said:


> The on state voltage for this device is fairly respectable. There's always a trade off between Cies (input cap), Vce(max) and Ic. The input capacitance is probably the best you'll get for a device of this spec. Do you really need all that power? Start off small - otherwise you're gonna have to start designing active snubbers, isolated gate drives, etc. Plus, for a prototype, you don't want to piss away $200 on an IGBT bridge every time you make a mistake
> 
> Sam.


Well I'm just going by the market for it  I personally will be running something like 300A max DC (so like 150A RMS) and only 84v....

I didn't have time to really dig into input capacitance... just saw the general specs and found it nice. 


At any rate... 

However... I'm pretty sure most designs aren't using large amperage gates for driving high amperage IGBTs, but I could be wrong... 

There's only a handful of chips that run even 2A out (which is what I intended to use at first).

Anyway I've been too busy lately to really dig around with this... I don't mind redesigning the gate if necessary... when I have time to do the math I will perhaps in a week.

32nF typical is lower than your every day run of the mill powerex module:
http://www.pwrx.com/pwrx/docs/cm300dy_24a.pdf
(which is priced higher)

There's always the possibility of dropping that IR gate driver for:
M57161L-01 from powerex:
http://www.pwrx.com/pwrx/docs/m57161l-01.pdf

Which does do the 7A+/-, but it's also about $35.
(and would draw a lot of power wasted)


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## samborambo (Aug 27, 2008)

Technologic said:


> Well I'm just going by the market for it  I personally will be running something like 300A max DC (so like 150A RMS) and only 84v....


84V? Are you serious? Why are you using a 1200V part? Why are you using IGBT devices???

General rule of thumb: over 600V max voltage, use IGBT. Below 600V, use MOSFET. Its all to do with losses. A typical high current IGBT has a Vce(sat) of 2V. With two devices on at any one time, thats 600W heat dissapation at 150A. For a similar MOSFET bridge module, the Rds on may be around 2 milliohms, equating to only 90W! And the MOSFET is cheaper!

I'm not taking into account switching losses of course which is dependent on the switching frequency and gate driver impedence, etc. Typically, IGBTs are slower and therefore have higher switching losses than MOSFETs. The main reason IGBTs are used is that MOSFETs are simply not feasible at higher voltages. Otherwise, MOSFETs trump them in probably every instance.

Sam.


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## Evan (Feb 20, 2008)

"84V? Are you serious? Why are you using a 1200V part? Why are you using IGBT devices???"

I second this sentiment.

"Typically, IGBTs are slower and therefore have higher switching losses than MOSFETs. The main reason IGBTs are used is that MOSFETs are simply not feasible at higher voltages. Otherwise, MOSFETs trump them in probably every instance."

That is not entirely true. IGBT's are faster when done right. There are a large number of physics projects (cyclotrons) that use IGBT for very fast KV/GV switching. You can do large numbers of parallel MOSFETs something you can't do, I feal, safely with IGBT. They used to make larger MOSFETs but they fell out of popularity. Oddly SCR based stuff persists but I don't know why.


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## Technologic (Jul 20, 2008)

samborambo said:


> 84V? Are you serious? Why are you using a 1200V part? Why are you using IGBT devices???


The reason for this is people in the community need a higher voltage option. There are already curtis controllers that can do 84v etc... however there's none that can really power your everyday car

I personally don't even need this controller.

a few parallel MOSFETS can do the job, but I'm not sure if they'll be cheaper (actually I'm quite sure they won't be)


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## Technologic (Jul 20, 2008)

I think I'm going to use this IGBT stage including predrivers:
http://www.fujisemiconductor.com/pdf/B0400081.pdf

Lots of reasons to, but it's actually much cheaper than attempting to manage the entire output stage.

I have a sample available for cheap to destroy etc... though I hope that's not necessary (should be basically good to go IMO)

As far as paralleling a bunch of MOSFETs that'd be fine if the gate driver circuit needed wouldn't almost make it that much stupider to not just grab that Fuji 6 pack... say you did 10 30A x 250v MOSFETS per high/low you'd need a output stage that supplied a lot of current generally speaking... a bit more than you'd for the same IGBTs.

You'd also end up right around the same price generally speaking... at about $2.50 per MOSFET x 20 per High/low side x 3...

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=2SK2967(F)-ND


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## Dennis (Feb 25, 2008)

Technologic, being the cheap bastard that you are. I found a chip for your DC-DC converter that will require less parts count and be cheaper than using a UC3842 PWM chip.

Here you go: http://www.powerint.com/products/topswitch-family/topswitch-hx

Now that is what I call the NEW LM317 and/or 78XX! As we all know how popular those linear regulators were back in the early days for hobbyist due to low component count and cheapness, only now we have a monolithic switching regulator with the same positives as those linear regulators!



I just found free software from that same company that does all the design work for you too! WOW!! WOOT! WOOT! Here ya go: http://www.powerint.com/design-support/pi-expert-design-software


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## Evan (Feb 20, 2008)

That is cool do not get me wrong but it is not appropriate for this application. I am fairly sure it could not take the power.


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## Dennis (Feb 25, 2008)

The control logic plus the gate drive together should be well within 300 watts. If you look at the various Topswitch models then you will see they have models for handling up to 333 watts in open frame environments or if in an enclosure with less cooling will be 177 watts.

Have a look: http://www.powerint.com/en/products/topswitch-family/topswitch-hx.

If this is going to be a motor controller then he can mount the topswitch device to the heatsink chassis enclosure of the motor controller which would allow the device to be able to output up to its power rating of 333 watts, but I like to conserve a bit and would say 300 watts max.

He will need like 15 volts at 15 amps max for the gate drive section assuming 2.5 amps required per igbt (6 of them). Which leaves 30 watts for the control logic (l left out a few watts for breathing room).

If this is not enough then a dedicated 300 watts can be made for the gate drive section and a separate Topswitch power supply for the control logic can be used. In the end it still comes out cheaper than using a UC3842 that requires much more components which add up in costs.


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## Evan (Feb 20, 2008)

Look at the input power though. I doubt it could handle the reverse breakdown voltage spikes from using a 500V transformer. 

You know if we do this right with a power transformer we could use it to also make a battery recharger and maybe a low output power inverter for 120V AC stuff.


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## Technologic (Jul 20, 2008)

Evan said:


> Look at the input power though. I doubt it could handle the reverse breakdown voltage spikes from using a 500V transformer.
> 
> You know if we do this right with a power transformer we could use it to also make a battery recharger and maybe a low output power inverter for 120V AC stuff.


I'm not liking the idea of a power transformer, because it will need to be custom wound.

however the only difference to make it a battery charger is to add windings for a "whatever pack voltage" or a selectable type of thing for that (with perhaps multiple switch function for different small voltage pack ranges).

That would just be an additional plug input into the power transformer... then rectification.

As far as low output 120v AC that would just need to hook back up into the battery instead of wall input and goes to the same charging input (but this time the + would come from the batteries instead of the wall). 

Incredibly simple to do both with a single additional set of windings IMO, but still will complicate the transformer (it'd be 4 layers of secondaries).

Ie. when the wall outlet is hooked up the transformer would send it to the primary then secondary windings then to the battery pack... when the wall outlet is disconnected, the battery pack would send the PWM DC to the transformer secondaries than to the primaries (at the reverse ratio) outputting 120v AC... Simple.

You'd just want a straight rectifier during charging, but that can be done through a digital switch or any number of things.


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## Evan (Feb 20, 2008)

First off there are 500V transformers. They might not all have the windings we need but they can be had. If we can't get one that fits exactly we could always use 250V ones in series. I am talking single phase after all so this is simple. The transformer need only have the following connections.

My Ideal Transformer
500V - Primary
220V & 24V - Secondary

I suspect that this might be a configuration we might be able to or make from a few pairs of transformers. There is enough industrial stuff that uses 500V and 24V that someone has to have made at least a few of these. As for having 220V well that could be hard but I suspect that could be fudged to be 250V which we could do via a center tap on the primary (500V). This would effectively use the secondary as an autotransformer.

Less Ideal
500V center tapped (250V) - Primary
24V - Secondary

I guess you could always find someone to help you rewind a 500V transformer to have more secondary windings. I know people who have done it. The work is unpleasant but doable. 

As for your thoughts on charging that idea is what I was getting at. Quit hijacking it.  Only I had something a more advanced in mind for the charging than just rectifying 500V. Constant current is not a good way to charge a lot of batteries. I would like to solve the cell balancing problem. 

"however the only difference to make it a battery charger is to add windings for a "whatever pack voltage" or a selectable type of thing for that (with perhaps multiple switch function for different small voltage pack ranges)."

This is not really practical because adding more taps to a transformer is hard and or expensive. Custom wound stuff goes up in price radically if you add the cost of more taps. I am doing this for 1 specific configuration and no more. Felixability here would be a cool thing to do but it is just to expensive.


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## Technologic (Jul 20, 2008)

Evan said:


> First off there are 500V transformers. They might not all have the windings we need but they can be had. If we can't get one that fits exactly we could always use 250V ones in series. I am talking single phase after all so this is simple. The transformer need only have the following connections.
> 
> My Ideal Transformer
> 500V - Primary
> 220V & 24V - Secondary


What do you intend to do with 24v? Or do you intend to send that to a chip for further taking down into 3 outputs?

I'd suggest this if you hadn't already planned it as the chip could compensate for any decreases in line voltage intrinsically (the outputs are hard wired at their respective voltages over a decently wide range of input voltages into Vcc)



> I guess you could always find someone to help you rewind a 500V transformer to have more secondary windings. I know people who have done it. The work is unpleasant but doable.


Actually it's less difficult than you'd think... I've wound transformers (by hand) and it does not take over 1 hour to do secondaries usually.

However, custom wound transformers aren't exactly expensive if done in volume... I suppose people would just order their own... or if in production keep a stock of common voltages (say 144v, 260v, 300v, etc) for the secondaries... afterall a single secondary with tap custom transformer is probably only a couple bucks from china for the minimal power we're talking about. ... or in the case of the charger portion it might just be best to do dual transformers one for the hard wired input stages (ie. for the AC low amperage signal into the transformer) and then swap out the charger transformer as needed (but would still functionally give 120v outlets no matter what since it's a charger). Charger transformers for 220v to many respective voltages are probably extremely widely available... I remember my amplifier days that 120v was converted to every respective voltage at a $5-10 price range... even allowing for HUGE levels of current needed for some audio amplifiers (which we wouldn't really need anyway).

As far as cell balancing I've found it's best to do this at the cell level with something in PCB form like the Goodrum thing... the reason is because so many Cells have different levels to cut off... hard wiring this is usually a bad idea and might make the thing unusable. 

some might need a 2.1v cutoff for cylindrical cells... and others might need a 2.5v or higher... and then lead acid 6v or 12v etc.


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## Evan (Feb 20, 2008)

"What do you intend to do with 24v? Or do you intend to send that to a chip for further taking down into 3 outputs?"

Yes I want to change the 24V down to the voltage needed for the logic and IGBT driver(s). 

"I'd suggest this if you hadn't already planned it as the chip could compensate for any decreases in line voltage intrinsically (the outputs are hard wired at their respective voltages over a decently wide range of input voltages into Vcc)"

Hmmm....

"Actually it's less difficult than you'd think... I've wound transformers (by hand) and it does not take over 1 hour to do secondaries usually."

My hat is off to you sir. That is if I wore hats it would be. I did my share of winding in my Tesla Coil days.

"However, custom wound transformers aren't exactly expensive if done in volume..."

Didn't we already discuss the volume thing. I remember banging on about economies of scale with you.

"I suppose people would just order their own... or if in production keep a stock of common voltages (say 144v, 260v, 300v, etc) for the secondaries... afterall a single secondary with tap custom transformer is probably only a couple bucks from china for the minimal power we're talking about."

Actually thanks to the unstable copper market it is always going to be more than a couple bucks. My concern is about the weight of a 500V primary and the core inside it. Weight = Wasted Power. Shame super capacitors are not more accessible and split-pi is patented.

"... or in the case of the charger portion it might just be best to do dual transformers one for the hard wired input stages (ie. for the AC low amperage signal into the transformer) and then swap out the charger transformer as needed (but would still functionally give 120v outlets no matter what since it's a charger). Charger transformers for 220v to many respective voltages are probably extremely widely available..."

Yes that was what I meant when I said ....
"I suspect that this might be a configuration we might be able to or make from a few pairs of transformers. There is enough industrial stuff that uses 500V and 24V that someone has to have made at least a few of these. As for having 220V well that could be hard but I suspect that could be fudged to be 250V which we could do via a center tap on the primary (500V). This would effectively use the secondary as an autotransformer."

Just pick up two 250V to 12V and put them in series. As long as you keep the coils in the right direction everything will be fine if not slightly heavier from the extra core weight.

"I remember my amplifier days that 120v was converted to every respective voltage at a $5-10 price range... even allowing for HUGE levels of current needed for some audio amplifiers (which we wouldn't really need anyway)."

LOL I have some very fun exotic transformers from some old airospace military hardware that were designed for a 400Hz configuration with multiple isolated outputs. Of course it was a lead brick of a thing.

"As far as cell balancing I've found it's best to do this at the cell level with something in PCB form like the Goodrum thing... the reason is because so many Cells have different levels to cut off... hard wiring this is usually a bad idea and might make the thing unusable. "

I don't know about the Goodrum thing. I have some ideas but I am not going to discuss it until I have solidified them more. Needless to say some programming and processing is involved for charging/discharging curves as you mentioned. I wan't to get away from having to wire connections to each cell sepeartely and balance the entire pack just by powering the ends. I have to make it work on paper first though.

"some might need a 2.1v cutoff for cylindrical cells... and others might need a 2.5v or higher... and then lead acid 6v or 12v etc."


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## Technologic (Jul 20, 2008)

Evan said:


> "As far as cell balancing I've found it's best to do this at the cell level with something in PCB form like the Goodrum thing... the reason is because so many Cells have different levels to cut off... hard wiring this is usually a bad idea and might make the thing unusable. "
> 
> I don't know about the Goodrum thing. I have some ideas but I am not going to discuss it until I have solidified them more. Needless to say some programming and processing is involved for charging/discharging curves as you mentioned. I wan't to get away from having to wire connections to each cell sepeartely and balance the entire pack just by powering the ends. I have to make it work on paper first though.


I apologize for my assumption. The goodrum/fetcher BMS was completed allowing for independent high voltage/low voltage cutoffs (with current shunting at full charge) for lithium cells

http://visforvoltage.org/forum/5192-4-24cell-battery-management-system-bms

It has the capabilities to shunt up to 1A or 2A (can't remember) per cell... which is more than enough for almost every battery system.

You could make it a tad beefier if you wanted..


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## Evan (Feb 20, 2008)

That looks a lot like Lee Harts work in the way it operates.

Well in any event we should provide a connector off the DC/DC board for the BMS on the 500V and 24V sides. Let people experiment. I suspect that BMS tech will catch up to batteries soon. It is due for some advancement. So the DC/DC should have connections for...

500V, 250V, 24V, 15V, 12V, 5V 
(the 3.3V should be regulated off the 5V to reduce noise on a board by board basis)


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## Technologic (Jul 20, 2008)

I'm not sure what to make of this recent quotation from a chinese supplier (surplus unused parts maybe?) that had those 600v x 300A 3 phase single units with pre-drivers... I was quoted $84/each 

Hi Matthew,
Thanks for your inquiry . The quotation is as below :
 6MBP300RA060 FUJI 50PCS MODULE $84.00 
It is unit price ; 
New and unused & 30 days quality warranty period 
Lead time : 1-2 days .
Payment term : WIre transfer ,Western Union,Paypal .


I'm not sure what to think of it actually as that price is pretty stellar/unbelievable. The unit would consistent of a very minimal amount of control and output components and could potentially cost 5-10 times less than etischer's and handle more power...

anyway... I should have time to finish up the throttle ramp etc in the next week or so (once finals are over) cheers.


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## Evan (Feb 20, 2008)

How are you going to cool that thing? Water pump? Look at the collector heat dissipation and unit thermal resistance. Now look at the graphs on the last two pages. That data sheet is less than perfect by far because it doesn't list the equations for thermal properties of the chip. I don't think going completely by eye is a good idea.


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## Technologic (Jul 20, 2008)

Evan said:


> How are you going to cool that thing? Water pump? Look at the collector heat dissipation and unit thermal resistance. Now look at the graphs on the last two pages. That data sheet is less than perfect by far because it doesn't list the equations for thermal properties of the chip. I don't think going completely by eye is a good idea.


You could do a water pump on it... that's how a lot of these controllers are cooled...

a lot of data is missing to be sure, but it's still probably one of the better options especially for the price (as it's 1/5th as much as doing 3 powerex half bridges rated the same)


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## Evan (Feb 20, 2008)

Odds are that the data is not missing it is omitted. You see this some times in less than favorable fab labs. They will do a run and the stuff that is off spec in some way will get it's own part number under some no name vendor. Same data sheet as the real product only minus the parts that the bad batch was inconsistent on.


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## Technologic (Jul 20, 2008)

Evan said:


> Odds are that the data is not missing it is omitted. You see this some times in less than favorable fab labs. They will do a run and the stuff that is off spec in some way will get it's own part number under some no name vendor. Same data sheet as the real product only minus the parts that the bad batch was inconsistent on.


Fuji Electric isn't a no name vendor (in fact it's the largest semiconductor company in Japan IIRC)... and that's one of their "product lines" 

http://pdf1.alldatasheet.com/datasheet-pdf/view/61102/FUJI/6MBP300RA060.html

Dissipation is decently high, but the graphs provided are more or less the same as all of their other products.

but if you take that vs the same dual powerex module the Fuji has a higher rated dissipation per collector:
http://www.pwrx.com/pwrx/docs/cm300dx_12a.pdf

Fuji: 1100w, Pwrx CM300, 960w

I don't think the Fuji is a bad product at all... they seem to be speced above Powerex at a much cheaper price (across the board)

the 3 phase Fuji $84 vs the 1 phase powerex $98 (in bulk)


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## Evan (Feb 20, 2008)

I know they are not no-name but still this seems fishy. I suspect you are going to just go ahead and do it regardless of what I say. I am just worried about you say lossing power on the highway at 65mph.


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## Technologic (Jul 20, 2008)

Evan said:


> I know they are not no-name but still this seems fishy. I suspect you are going to just go ahead and do it regardless of what I say. I am just worried about you say lossing power on the highway at 65mph.


No doubt it seems fishy. The offer seems fishy though not the product 

I have a few other offers ranging from a low of $221 to a high of $440 for the same 3 phase IGBT module.

I'm questioning that vendor actually, but not really too concerned about the product.

And at that price I'd be foolish not to at least try it IMO.... since it's a well known highly respected semi company.


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## Johny (Jul 21, 2008)

Hi guys. just scanning this thread and I hope I didn't get the wrong idea. IGBTs that need about 9 Amps of gate drive only need it for a few uS. It's just to charge/discharge the gate. the continuous power required by gate drivers is very small - like a few watts.


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## Thalass (Dec 28, 2007)

This is a great project. Would it be possible to double up on the output sections, to allow for two motors? My EV will have two induction motors (two smaller ones, rather than one large one + gearbox). 

The main issue is what will happen in a tight turn, with the rear motor travelling a shorter distance than the front motor. I think (my brain simulator isn't that accurate) you will end up with the front motor trying to slow down, while the rear motor tries to accelerate. Which would result in current flow from one motor to the other? Or something. Which is why you can't just parallel two motors off the one power section. 

Two power sections with individual position feedback (vector control?) should solve this, but by that stage you might as well have two whole controllers, or use software to control the power sections!


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## samborambo (Aug 27, 2008)

Thalass said:


> This is a great project. Would it be possible to double up on the output sections, to allow for two motors? My EV will have two induction motors (two smaller ones, rather than one large one + gearbox).
> 
> The main issue is what will happen in a tight turn, with the rear motor travelling a shorter distance than the front motor. I think (my brain simulator isn't that accurate) you will end up with the front motor trying to slow down, while the rear motor tries to accelerate. Which would result in current flow from one motor to the other? Or something. Which is why you can't just parallel two motors off the one power section.
> 
> Two power sections with individual position feedback (vector control?) should solve this, but by that stage you might as well have two whole controllers, or use software to control the power sections!


If there's at most a 10% difference in angular velocity (rotational speed) between the front and rear motors, you can drive them off a single 3 phase inverter with V/F control. Vector control won't work as the controller is basing the voltage waveforms on what it sees happening at the motor. If you put more than one motor on a vector controlled inverter it'll get confused.

This should work well for induction motors since torque is proportional to the angular velocity "slip" from the rotating EM field. Don't try PMSM or BLDC (synchronous types) as they will fight hard to rotate at exactly the same speed. Synchronous type motors do exactly what it says on the tin - the rotate synchonously with the EM field. Torque for a synchronous motor is proportional to the angle between the rotor and the EM field.

For your setup, the induction motors will share the torque load when travelling in a straight line. If there's too much of a speed difference between the front and back wheels, the faster motor will become negative torque (regen) while the slower motor will pick up all the positive torque. You've got around +/-5% of the inverter frequency before this becomes noticable.

The same concept can be used to do away with the differential by having one induction motor on each wheel. They'll act like a limited slip differential without the need for any electronic control.

Sam.


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## Evan (Feb 20, 2008)

I know I have been off of this for a while now and for that I apologize. I am working on the DC/AC/DC converter to make recharge the batts and power our low voltage electronics for the processors and firing the IGBTs. 

Technologic - I know you might be ok with winding your own transformers but for those who don't I took some time to find some premade replacements. I don't know how fast the charging method will work given the current rating on these transformers but still it will prove the concept.
1 of these
http://www.herbach.com/Merchant2/me...AR&Product_Code=TM97XFR2965&Category_Code=XFR
or 2 of these
http://www.herbach.com/Merchant2/me...AR&Product_Code=TM96XFR2860&Category_Code=XFR


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## samborambo (Aug 27, 2008)

Hey Technologic, it'd be great to see where you're at with your controller design and hopefully share some ideas.

My design is based around an old design I did a couple of years ago. It's posted on my DIYEC blog. I'm redesigning around a bigger surface mount PIC with some room for future software expansion.

I want to now use the inverter for a 3 phase rapid charger also by having a changeover contactor on the motor phases. Here in NZ our 3 phase power is 400V phase to phase which should work well. I need to keep in mind the maximum rectified utility voltage 586V and the minimum battery voltage of 192x 3V (LiFePO4) as the inverter will be operating in boost mode to charge the battery. I'll probably be using the LTC6802 for the BMS and control it from the motor controller.

Sam.


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## Evan (Feb 20, 2008)

Technologic moved to another country and is kind of tied up with that last time we talked.


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## Technologic (Jul 20, 2008)

Evan said:


> Technologic moved to another country and is kind of tied up with that last time we talked.


Not moved... just busy in another country visiting

I've been looking for a real life job at home in the US, studying, and planning internships, etc.

I should have more time to myself soon (I'll be back in the US in July)... but I'm actually probably picking up a master's while I'm working on my J.D still this fall (just an extra thing to assure I have no time at all).

I'll be around though working on this when I feel less exhausted all of the time.


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## david85 (Nov 12, 2007)

Looks like this is a dead thread, but one thing I found out recently is there are ways to integrate a DC/DC converter into the controller itself. I had my BLDC motor controller open yesterday and there are several sealed, solid state converters of various sizes. Some are on the main control board, and some are separate to power the 24V cooling fans. They would not be enough for powering 12V accessories like heater and lights for the car, but they are plenty to run the controller electronics. My controller has no secondary voltage input, all it uses is direct traction voltage and the internals take care of the rest.

Hope we do get Evan and Technologic back eventually.
Good luck guys, where ever you are.


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## Evan (Feb 20, 2008)

david85 said:


> Looks like this is a dead thread, but one thing I found out recently is there are ways to integrate a DC/DC converter into the controller itself. I had my BLDC motor controller open yesterday and there are several sealed, solid state converters of various sizes. Some are on the main control board, and some are separate to power the 24V cooling fans. They would not be enough for powering 12V accessories like heater and lights for the car, but they are plenty to run the controller electronics. My controller has no secondary voltage input, all it uses is direct traction voltage and the internals take care of the rest.
> 
> Hope we do get Evan and Technologic back eventually.
> Good luck guys, where ever you are.


Thanks. Sorry I had to just vaporize like that. I have been busy with work lately. I will have to check out your conversion thread!

We are/were both planning on using converters. I was just planning one that was a bit more complex than I meant for it to be at the start. My progress so far has been almost non-existent but that will change soon.

The cars heater/AC should run of full battery power for many reasons. Headlights, wipers and etc. should use a lower noise DC/DC converter. This was always my plan at least. The controller/inverter power is an other story because most modern stuff will need +3.3V, +5V/+12V, and the IGBTs need +15V or something similar. Also you want to keep the IGBT power and everything else isolated. So this requires multiple DC/DC converters.


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## david85 (Nov 12, 2007)

We all have to make it in the real world. Completely understandable but nice to know you're still alive. I basically did squat with my car all summer because of my work.

Hmm, I guess that explains the multiple DC/DC converters I saw in there. Still have a lot to learn.

You can add vacuum pump to that list. Brian found a nice one that can run off full traction DC voltage. Blower fans can be replaced with brushless computer fans. Signal lights switched over to LED, and so on. In the end, the only real draw would be the headlights or rear window defogger if applicable (defogger alone was 15~20 amps).

I know I could probably half my car's 12V requirements with some of that modding. With all the stock accessories running I measured nearly 60 amps. The more you run outside of the converter, the more efficient everything will be anyway. I couldn't believe how much power even the signal lamps eat up. Blower fan was a solid 20 amps.


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## samborambo (Aug 27, 2008)

My AC controller design relies on the 13.5VDC system to power the gate drives and microcontroller. The main reason for me was simplicity in design (not having to design another high voltage DC-DC converter) and also retaining the 12V battery as a consequence of having 12V power steering. Without the power steering I could probably get away with powering the 12V system straight from a DC-DC converter. I'm now modding a ATX PSU to use as a float charger.

There's an inherent safety factor in powering the controller separately. You can virtually guarantee that you're not going to have any runaway controller because it can be fully shutdown by switching off the ignition.

Sam.


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## david85 (Nov 12, 2007)

Well since we need one anyway to power car accessories, there is still the main contactor (powered by 12V) to cut power to the controller. Main emergancy shut off is also a final way to kill everything.


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## Technologic (Jul 20, 2008)

david85 said:


> We all have to make it in the real world. Completely understandable but nice to know you're still alive. I basically did squat with my car all summer because of my work.
> 
> Hmm, I guess that explains the multiple DC/DC converters I saw in there. Still have a lot to learn.
> 
> ...


I still haven't finished the DC/DC converter on this, but to be honest it was placed on the back-burner during my Summering and I wound up transferring law schools.

I've actually been trying to finalized buying a rental income beachfront property in the Bahamas over the last month and a half.

I'll be around soon again I hope.
Looking forward to catching up, David and Evan and the rest.
Haven't given up at all, but this market is destroying the legal industry (literally) and I had to face facts and transfer up.


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## Arlo (Dec 27, 2009)

Subscribed


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## Tesseract (Sep 27, 2008)

Arlo said:


> Subscribed


This thread died over 3 years ago... I wouldn't hold my breath waiting for "Technologic" to deliver on his brash claims anytime soon.


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## Arlo (Dec 27, 2009)

Tesseract said:


> This thread died over 3 years ago... I wouldn't hold my breath waiting for "Technologic" to deliver on his brash claims anytime soon.


 Lol ok. I was in a hurry and just wanted to mark it so I could read it later.


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