# A Challenge to all Engineers...



## Technologic (Jul 20, 2008)

fugdabug said:


> Now, I am 56 years old I don't have YEARS to year and YEARS to wait... SOMEBODY up to this?
> And don't give me any 'economics of the matter' crap... Somebody put one out here and let everybody build one! (please)
> 
> fugdabug


I'm working on one... that I will release a schematic for if I ever get it to work.

I can't offer any sort of time frame... but it's constantly being worked on *sighs*

If I encounter issues in the spring with it... I'll be hiring an EE from my college (Duke University) to trouble shoot it. Question I reckon anyone ponying money up for anything is, will they get their money back? Wish I could help in the short term mate. But my own project won't be put on hold for much longer.

Programmable controllers really aren't necessary... and once you start getting into that range you're looking at top end masters/doctorate EEs... not DIYers.

Just try to find a book on programmable controllers for engineers... there AREN'T any. I have several Nobel prize nominees in my BME and CE departments here, and I can not find much help/guidance outside of being told "you need to take engineering courses to understand", a luxury of time I don't have to waste (about programmable ones).


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## fugdabug (Jul 14, 2008)

Technologic said:


> Just try to find a book on programmable controllers for engineers... there AREN'T any. I have several Nobel prize nominees in my BME and CE departments here, and I can not find much help/guidance outside of being told "you need to take engineering courses to understand", a luxury of time I don't have to waste (about programmable ones).


Ah yes,... Isn't it interesting:
We are at a point in our history when we really need open source references. I went online looking for references applicable to EV's and 'How-to' (this was in early April-May of this year), I found three books that were repeated over and over ... DIY elect. car - Brant, Convert It - Brown, and Motor and Controllers - Gottlieb. ALL three were from the early 1990's... I searched further and found books in the $160.00-$300+ range on Electric Vehicle Technologies... yeah right!... are you willing to buy a book full of words and that may have very little to do with the actual construction and tech in reality??? For me the answer was obvious ... buy all three and work from there. But the components, ah, that is another story eh?.. I know I came off rather flustered but I myself am trying to get back into 'study mode'. I am revising my basic understandings trying to get into the electronics I never studied in high school or college... I figure I may not be able to design but I can at least understand the basic component functions!... and the building part is a matter of following schematics and buying a proper 0-scope. I hope you do get your project done soon and proven! That is what we need more of YOU!!!.. I am going to approach some folks at the local community college that offers an engineering program, and see if I can't spur some sort of innovation in their class offerings in the way of EV tech.


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## Technologic (Jul 20, 2008)

fugdabug said:


> But the components, ah, that is another story eh?.. I know I came off rather flustered but I myself am trying to get back into 'study mode'.


 
http://www.amazon.com/Control-Elect...=sr_1_1?ie=UTF8&s=books&qid=1227711337&sr=1-1

Is probably the best book I've come across for the design phase of a controller system. Yet I refuse to pay that much and can't find one used.

Most motor controller books are troubleshooting/repair guides and have nothing to do with a scratch design.

I'm still working on it.


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## Bugzuki (Jan 15, 2008)

Are you looking for a DC Brushed motor controller? You did not put any spec for that. I have been doing some work on a BLDC/induction controller, but it is different then a straight DC controller.

I think that the main problem is is that the companies that are currently making controllers don't want to see an opensource systems, so the hold on to there information tight.


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## david85 (Nov 12, 2007)

I was wondering about the brushless DC or AC myself. Would be nice to have something a little better than the old series wound brushed motors.


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## saab96 (Mar 19, 2008)

Bugzuki said:


> I have been doing some work on a BLDC/induction controller, but it is different then a straight DC controller.


Is there such a thing as an affordable brushless DC motor for freeway-capable EVs? I've never seen such a thing.


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## david85 (Nov 12, 2007)

saab96 said:


> Is there such a thing as an affordable brushless DC motor for freeway-capable EVs? I've never seen such a thing.


What would you consider affordable?


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## fugdabug (Jul 14, 2008)

NOPE. Talking the standard DC series wound motor... like my D&D Systems ES31B... straightforward and tunable for torque and power %. Nothing fancy not complicated by bells and whistles... something a wrench monkey could use to control his pot throttle to motor translation. A simple 'brain' between traction pack, pot and motor. You know 'simple'.
But enough to handle the rigors of 72 - 168VDC and say 500A.


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## Technologic (Jul 20, 2008)

saab96 said:


> Is there such a thing as an affordable brushless DC motor for freeway-capable EVs? I've never seen such a thing.


Yeah there's quite a few, the problem is people are still using 2500-3000lb conversions, with Cds of .33-.5 

I'd say there's a lot to gain from cutting weight (say by building a ground up tube frame car/fiberglass/kevlar reinforced) car than there is by throwing a larger motor and larger batt pack in a premade car.

"Purpose built" is the motto I intend to built my EV with (and any possible clones of it I build for people).

a 8kw brushless DC motor would run you about $900? at least if you source it from the real sources.


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## david85 (Nov 12, 2007)

Brushless motors are a lot like controllers for DC brushed motors. The raw parts are not very expensive ( a few $100 in material for something over 200kw), whats needed is some one to build such a drive system that isn't working for siemens, GE or some other big company.

Although anything would be better than what we have right now if it were reliable and affordable (brushless or not).


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## Zanthic (Jul 2, 2008)

I have been lurking here for a while and thought maybe it was time to jump in!
I have 20 years embedded controller experience, 13+ years CAN bus, and recently did enough contract work for a hybrid electric vehicle battery company to get me interested in all things electric vehicle related. This list is a little out of date but it shows some of the projects I have been involved in www.zanthic.com/projects.htm
I have also been experimenting with the Linear 6802 BMS IC and have done some relatively low current motor drivers (under 40 amp). I would be willing to provide whatever resources I can to creating an open source system, both on the BMS side and the motor controller side. I also have an existing platform of microcontroller boards that allow the download and configuration of I/O devices all across the CAN bus . This might form the building blocks to a larger system if useful. 
Steve


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## Harold in CR (Sep 8, 2008)

Sounds like a winner to me. Zanthic, thank you for your most generous offer.
Just wish I knew electronics. 

OK guys, lets see what can come of this. I even have an O-scope to donate to someone that KNOWS how to use it, if I can be allowed to be a part of this operation.


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## JRP3 (Mar 7, 2008)

Technologic said:


> Yeah there's quite a few, the problem is people are still using 2500-3000lb conversions, with Cds of .33-.5
> 
> I'd say there's a lot to gain from cutting weight (say by building a ground up tube frame car/fiberglass/kevlar reinforced) car than there is by throwing a larger motor and larger batt pack in a premade car.


Building a car from the ground up is about ten times the work of just doing a conversion, not to mention getting it certified for road use. Using existing vehicles is the only reasonable option for the majority of individuals. Certainly smaller and lighter ones are available, as well as dropping weight wherever possible.


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## Technologic (Jul 20, 2008)

JRP3 said:


> Building a car from the ground up is about ten times the work of just doing a conversion, not to mention getting it certified for road use. Using existing vehicles is the only reasonable option for the majority of individuals. Certainly smaller and lighter ones are available, as well as dropping weight wherever possible.


 
The question I always had, was spending upwards of $3000-10,000 more to convert a engineless steel car (depending if you go lithium or not) still will have a lot of the many moving parts that aren't necessary for an EV that weighs 700-800 lbs, seats 2 with a Cd in the 0.15 range. You could easily shed the transmisson, power steering, air compressor, 1/2 or more of the battery power, yet increasing the range by 2-3 times (120 miles off of 8kwh seems quite possible). Lower RPM motors, lower voltages, etc etc.

It's more difficult, at least the FIRST one would be, but you'd be in a much better long term situation. Not to mention you'd have the ability to clone the car in "days" (assuming you made the proper molds, jigs, etc).


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## JRP3 (Mar 7, 2008)

Technologic said:


> You could easily shed the transmisson, power steering, air compressor, 1/2 or more of the battery power, yet increasing the range by 2-3 times (120 miles off of 8kwh seems quite possible). Lower RPM motors, lower voltages, etc etc.


You could still do much of that if you picked the right vehicle. Remember full sized cars and trucks didn't always have power steering or power brakes and were quite drivable.


> It's more difficult, at least the FIRST one would be, but you'd be in a much better long term situation. Not to mention you'd have the ability to clone the car in "days" (assuming you made the proper molds, jigs, etc).


Maybe a kit car would allow you to do almost the same without starting from nothing. A fiberglass bodied T-bucket would be light and simple and it would be pretty easy to make up an aero front end for it. There's a thread on one somewhere around here.


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## Bugzuki (Jan 15, 2008)

Madmac is working on an AC induction/BLDC controller design. Last time I talked to him he was going to get some prototype board made up this fall. He is in England, so that made it a little hard for me to work with him, but if we could get him to let us help maybe we could get his design moving forward faster. 

It is kind of a toss up if it is better to work on multiple designs or focus on one.


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## LeTank (Jun 24, 2008)

DC / DC Controller patent 
A search in google for DC/DC controllers patents is easy (I am being a smarty here. haha) and gives you a list of patents that relate to such, which you can then go by to build your own. 
You can follow these links I will give below to find the patents, then goto www.pat2pdf.org and type in the patent number and you can download it as a pdf file.

Here is a patent for DC/DC controller on an Electric Motor in an Electric Vehicle.
http://www.freepatentsonline.com/4158158.html

Here is the patent with a multi-phase sync buck system for a controller on an electric vehicle.
http://www.freepatentsonline.com/6262566.html

Here is a link to the pat2pdf site where you can download the patent in pdf format.
http://www.pat2pdf.org/
Hope this helps.
Josh

When they refuse to give you any details on their products, I just go the source. The patent office is nice enough to give it all away to the public when companies refuse to. =)


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## Qer (May 7, 2008)

Technologic said:


> Programmable controllers really aren't necessary... and once you start getting into that range you're looking at top end masters/doctorate EEs... not DIYers.


Uhm? You're saying you need a masters to program, for example, an AVR micro controller? Damn. I better stop immediately then before I accidentally blow up the world...


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## Technologic (Jul 20, 2008)

Qer said:


> Uhm? You're saying you need a masters to program, for example, an AVR micro controller? Damn. I better stop immediately then before I accidentally blow up the world...


 
Lol I was merely commenting on when that sort of thing is "taught" to students generally.


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## Qer (May 7, 2008)

Technologic said:


> Lol I was merely commenting on when that sort of thing is "taught" to students generally.


Well, if you have coded C or C++ it's not THAT hard to learn to program an AVR. It's pretty different compared to writing programs in Windows/Linux since it's a VERY limited environment (you usually talk kilobytes or even bytes rather than megabytes) but I'll gladly give advices or answer questions.

Writing the actual program will, however, put me in a precarious situation. Sorry...


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## ga2500ev (Apr 20, 2008)

Folks,

The software isn't the issue. In fact you don't really need software at all. It's a luxury. A simple 555 PWM circuit like this one:

http://www.dprg.org/tutorials/2005-11a/index.html

would be a suitable starting point for a control circuit.

As I have stated over and over again, all the complexity and reliability issues of a motor controller start from the motor and work their way backwards towards the PWM driver. Working backwards, the issues are:

1. Power transistor(s) and freewheeling diode.
2. Power capacitors.
3. Driver circuit for power transistors.
4. Isolation of power electronics from control electronics.

Now the chances of getting all of this gift wrapped is pretty slim Fudabug. Anyone who takes the time to package up everything is going to want to get a return on that investment.

What we need to do is come up with one simple way to pull off each subsystem and stick to it. Find one type of correct MOSFET, one type of capacitor, one single simple driver circuit.

That's what it's going ot take to get done.

And I would advise not worrying about the software. There are more than enough software guys, like myself, that would have no problem with that. None of the control electronics would take much more than a PICAXE with some simple programming. And it has the RS232 interface for programming that was asked for.

So I'll start. From Tesseract's excellent discussion from a few threads ago a dirt simple controller can be built using a IGBT module as its power transistor element. Two PowerEX 1200V 600A IGBT modules can be had from Ebay for as little as $100 and will serve both as the switching transistor and the freewheeling diode. I would derate to half the current and limit to 300A for safety.

The next question is how to drive it. The key is understanding that you need a stiff driver to move the gate charge on the IGBT quickly. This means using high current (20-25A) power transistors. They should be organized into a push/pull configuration as described here:

http://www.antonine-education.co.uk..._Mod2/Topic_2_9/topic_9__power_amplifiers.htm

One problem is that a dead short occurs if both transistors are on at the same time. Two solutions are having a resistor on the output of both transistors, thereby limiting the current draw or by using a deadband circuit that guarantees that one transistor goes off before the other comes on. A sample of that circuit can be found here:

http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=6203

I would be ready to tackle this project if I could get some clarity about how the piece fit together.

We just need to work at it.

ga2500ev


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## ww321q (Mar 28, 2008)

Well here then ! lol !
http://vehiculeselectriques.free.fr/controller/
This is from Richard Valentine (I have his book to)
Even shows proper way to lay out to work good (ya know short leads ect)
good stuff J.W.


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## Mjolinor (Sep 15, 2008)

555 timers are not a good choice, the problem being that when the output switches it crowbars the power supply leaving you with a lot of smoothing to do, signal production is really trivial to programme with a PIC or any other micro controller and leaves you with something a lot more versatile where you can add analogue inputs or LED outputs with no extra cost.


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## Qer (May 7, 2008)

ga2500ev said:


> One problem is that a dead short occurs if both transistors are on at the same time. Two solutions are having a resistor on the output of both transistors, thereby limiting the current draw or by using a deadband circuit that guarantees that one transistor goes off before the other comes on.


This is one of those problems that I, personally, would at least look at using a microcontroller to solve because it's so much easier to optimize the timing in software than with delays in hardware. And even if I agree with that it's not the software that is the key issue in a controller I think it's a good idea to add a microcontroller and software from the beginning to try to simplify the hardware as much as possible.

At least that's how I would've done it, but I'm a software guy.


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## TheSGC (Nov 15, 2007)

ga2500ev said:


> 1. Power transistor(s) and freewheeling diode.
> 2. Power capacitors.
> 3. Driver circuit for power transistors.
> 4. Isolation of power electronics from control electronics.
> ...


The Powerex 1200V 600AMP only needs 8 AMPs peak gate grive if we stick to 16 KHz. As for that list, I have #1 and #3 just about complete, but need an oscilloscope to finish the gate resistor/driver setup. For #2 I am thinking of two 250 volt 5600 uF caps, the Panasonic ECE-P2EA562HA. As for isolation, optocouplers obiviously, but I have yet to find a DC-DC converter that will output 15 volt and 10 AMPs.


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## ga2500ev (Apr 20, 2008)

Mjolinor said:


> 555 timers are not a good choice, the problem being that when the output switches it crowbars the power supply leaving you with a lot of smoothing to do, signal production is really trivial to programme with a PIC or any other micro controller and leaves you with something a lot more versatile where you can add analogue inputs or LED outputs with no extra cost.


The problem though is that a lot of the hobbyists here are like Steve Ciarcia of Circuit Cellar fame. His favorite programming language was solder.

Exactly what is the impact of crowbarring a power supply with a part with a maximum 200 mA output anyway?

I've figured out that folks who don't use microcontrollers are fearful of them. Think of all the non programmable methods as a transition that better meets their comfort level.

ga2500ev


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## ga2500ev (Apr 20, 2008)

Qer said:


> This is one of those problems that I, personally, would at least look at using a microcontroller to solve because it's so much easier to optimize the timing in software than with delays in hardware.


Actually hardware is probably better here for the deadbanding issue. Any microcontroller worth its salt will use hardware PWM to generate the signal. None that I know of have differential signaling and deadbanding in the hardware module. That means you'd have to do the PWM and everything else completely in software.


> And even if I agree with that it's not the software that is the key issue in a controller I think it's a good idea to add a microcontroller and software from the beginning to try to simplify the hardware as much as possible.
> 
> At least that's how I would've done it, but I'm a software guy.



When one of the two solutions is as simple as two power resistors, it may be a bit much.

ga2500ev


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## Zanthic (Jul 2, 2008)

I'm going to throw an idea out there and let you guys pick it apart.

What if the controller consisted of some number of separate modules where you plug in as many as you need to supply the amount of current your application needs. Each module would be a completely stand alone device rated at, say, 50 amps each. Each module would plug into a bus bar system, maybe even the way breakers plug into a breaker panel. Each module uses a resistive element for current sensing with a fast comparator that limits the current to 50 amps, even if the output is a dead short. This would eliminate the problems of parallel mosfets where one goes and it starts a cascade failure. You could literally have a single 50amp module on a 600amp motor and it would get a maximum of 50 amps. (of course it isn't going to have any torque but it also isn't going to smoke) It also eliminates the timing issues of one device starting a fraction of a second to fast and over currenting and blowing, each one can come up to speed and even if initially one is doing 50 amps and the second is doing 30 amps (at that instant, until it catches up) it doesn't matter. Each module has a opto isolated input driven in parallel with all the other modules with one simple microprocessor doing PWM control and course current limiting through an overall current sensor. As far as cost goes, yes there would be more cost to seperate modules with current feedback on each module but it would more than make up for the fact that it should be bullet proof and the cost for a simple current limiting feedback circuit is not that much.
I am not a high current motor control expert so tell me what I'm not considering in this idea...


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## Qmavam (Aug 17, 2008)

TheSGC said:


> As for isolation, optocouplers obiviously, but I have yet to find a DC-DC converter that will output 15 volt and 10 AMPs.


 42volts to 60 volts in, 15v at 13 amps out. $25.00, only one left!

http://www.mpja.com/prodinfo.asp?number=11325+PS

Mike


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## TheSGC (Nov 15, 2007)

Zanthic said:


> I'm going to throw an idea out there and let you guys pick it apart.
> 
> What if the controller consisted of some number of separate modules where you plug in as many as you need to supply the amount of current your application needs. Each module would be a completely stand alone device rated at, say, 50 amps each. Each module would plug into a bus bar system, maybe even the way breakers plug into a breaker panel. Each module uses a resistive element for current sensing with a fast comparator that limits the current to 50 amps, even if the output is a dead short. This would eliminate the problems of parallel mosfets where one goes and it starts a cascade failure. You could literally have a single 50amp module on a 600amp motor and it would get a maximum of 50 amps. (of course it isn't going to have any torque but it also isn't going to smoke) It also eliminates the timing issues of one device starting a fraction of a second to fast and over currenting and blowing, each one can come up to speed and even if initially one is doing 50 amps and the second is doing 30 amps (at that instant, until it catches up) it doesn't matter. Each module has a opto isolated input driven in parallel with all the other modules with one simple microprocessor doing PWM control and course current limiting through an overall current sensor. As far as cost goes, yes there would be more cost to seperate modules with current feedback on each module but it would more than make up for the fact that it should be bullet proof and the cost for a simple current limiting feedback circuit is not that much.
> I am not a high current motor control expert so tell me what I'm not considering in this idea...


I see where you are going with this. I do see some flaws, but I'll sit down and come up with something. I think if you made these individual "sections" more like single controllers, but when connected a "master" controller took over and did all the work it would make a very appealing system. 

Man, now not only did you get me thinking, I now have a reason to use my PIC processors and 100volt MOSFETs that I have been saving for some sweet controller design.


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## Mjolinor (Sep 15, 2008)

Has anyone looked at using a UPS as a basic starting point for a controller, most of what you need is in there, charger and power output stage.

Frequency is fixed at 50 or 60 Hz but I am sure it wouldn´t be rocket science to modify them as long as the power output fits your requirements. 

There is any number of scrap ones at all kinds of sizes as most people bin them when the batteries go naff.


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## Qer (May 7, 2008)

ga2500ev said:


> Actually hardware is probably better here for the deadbanding issue. Any microcontroller worth its salt will use hardware PWM to generate the signal. None that I know of have differential signaling and deadbanding in the hardware module. That means you'd have to do the PWM and everything else completely in software.


Yep, but it's not even hard to do PWM "manually": Let's say you have the signal to the pull up transistor on PORTB, PB0, the pull down on PORTB, PB1 and we use timer0 for controlling the PWM, then the code would look something like this:

ISR(TIMER0_OVF_vect)
{
// Turn off pull down.
PORTB &= ~_BV(PB1);
// Wait a while
int16_t delay = 10000;
while (delay--);
// Turn on pull up.
PORTB |= _BV(PB0);
}


ISR(TIMER0_COMPA_vect)
{
// Turn off pull up.
PORTB &= ~_BV(PB0);
// Wait a while
int16_t delay = 10000;
while (delay--);
// Turn on pull down.
PORTB |= _BV(PB1);
}

Then you can control the pulse width with the OCR0A-register. Of course, there's a few more details to iron out but this is in essence the needed code. Trust me, it works. I've done it with an AVR to morph text in text on an LCD at work.

I'm not saying hardware won't work, but I think that adding a micro controller might be a good thing to make things more flexible in the long run and, as someone already pointed out, there's several here that knows software anyway...



ga2500ev said:


> When one of the two solutions is as simple as two power resistors, it may be a bit much.


It's seldom soldering the components in place that is the problem, it's when you have to fine tune it later that hardware usually turns more tedious than software. Anyway, just my $0.02 as a software engineer that isn't totally alien to hardware as well. Carry on, do as you like...


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## JRP3 (Mar 7, 2008)

Mjolinor said:


> Has anyone looked at using a UPS as a basic starting point for a controller, most of what you need is in there, charger and power output stage.
> 
> Frequency is fixed at 50 or 60 Hz but I am sure it wouldn´t be rocket science to modify them as long as the power output fits your requirements.
> 
> There is any number of scrap ones at all kinds of sizes as most people bin them when the batteries go naff.


I don't know, I'm trying to find a used one without batteries of 1600 watt capacity or higher and people still want $100 or more plus shipping, which is also high because these things are heavy even without batteries. If you know of a place that's junking these let me know  I want to hook it up to my 48 volt pack in my AMPhibian for a portable 120volt power source


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## ga2500ev (Apr 20, 2008)

Qer,

You missed my point. I wasn't saying not to use a microcontroller in this instance. In fact I was advocating using a microcontroller with built in PWM. All I was saying is that instead of managing PWM like you have in your code that hardware PWM using the PWM module of the microcontroller coupled with external hardware deadbanding trivializes the problem.

I'm a firm believer in working just as smartly in software as I do in hardware. Software guys tend to do everything in software, hardware guys the opposite. I'm agnostic and pick whichever solves the problem most effectively.

With my suggestion PWM is simply setting up the PWM frequency and turning on the PWM module. After that you just need to write the PWM register to change speeds. No additional software required for that task.

ga2500ev


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## Mjolinor (Sep 15, 2008)

JRP3 said:


> I don't know, I'm trying to find a used one without batteries of 1600 watt capacity or higher and people still want $100 or more plus shipping, which is also high because these things are heavy even without batteries. If you know of a place that's junking these let me know  I want to hook it up to my 48 volt pack in my AMPhibian for a portable 120volt power source


As an Englishman living in Greece I doubt that any sources I had would be much good to you, not that I have any anyway.


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## Qer (May 7, 2008)

ga2500ev said:


> All I was saying is that instead of managing PWM like you have in your code that hardware PWM using the PWM module of the microcontroller coupled with external hardware deadbanding trivializes the problem.


Yep. Or rather, it moves the problem from software to hardware. I just wanted to point out that it's quite possible to solve it in software so it can be fine tuned without a soldering iron. However, what path you choose is of course up to you (or whoever implementing it).


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## ga2500ev (Apr 20, 2008)

Qer said:


> Yep. Or rather, it moves the problem from software to hardware. I just wanted to point out that it's quite possible to solve it in software so it can be fine tuned without a soldering iron. However, what path you choose is of course up to you (or whoever implementing it).


The trade off is having to manage more tasks in software. It's the same problem with bitbanging UARTS and virtual timers. If can all be done with software but with each added task the complexity increases.

And deadband tuning is something that only needs to be done once. Even if it needed to be retuned a 15 turn pot can make it as easy as turning a screwdriver.

Both approaches are workable of course. But I feel pretty strongly that if a hardware module in a microcontroller can be used to solve a task with minimal software, then that's the most straightforward approach.

ga2500ev


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## Technologic (Jul 20, 2008)

ga2500ev said:


> The trade off is having to manage more tasks in software. It's the same problem with bitbanging UARTS and virtual timers. If can all be done with software but with each added task the complexity increases.
> 
> And deadband tuning is something that only needs to be done once. Even if it needed to be retuned a 15 turn pot can make it as easy as turning a screwdriver.


As far as DIY purposes are concerned I agree with you here ga2500. Pulse width modulation handled on a hardware basis would tend to be more "layman" friendly. Deadbanding can be handled per voltage requirements without needing software etc changes.

Software might be the ticket for a controller/BMS all in one system (say on a commerical EV). I have a feeling that for a DIY basis/some commerical basis, doing a hardware only setup will be cheaper. Still very interested in Qer's input, though it's way above my knowledge *sighs and keeps lurking trying to keep up*


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## fugdabug (Jul 14, 2008)

ga2500ev said:


> Folks,
> 
> The software isn't the issue. In fact you don't really need software at all. It's a luxury. A simple 555 PWM circuit like this one:
> 
> ...


Nice articles (and good research!). Now if I can find the precise ratings of the particular pieces to match the idea... I have caps and gate transistors, diodes, resistors etc. a-plenty, if I can come up with the basic design I can then build a board, mask and 'burn' it to the specified need. It is the basic process of modularity that I need to understand... or for that matter ANYBODY needs to understand. Like a CPU there are modules to the construction... or any mechanism as well... 
Electricity from traction pack comes into... electricity for controller system comes into... from there it goes to... pretty 'paint-by-number' picture... but that is what I am having trouble wrapping my head around at this time... Maybe if I can find the proper solvent to wash down the Kelly board and clean away the masking I can then trace and get a better idea of the flow of current with in the system devised by them... to fill in the 'paint-by-number' sequence. A flow chart of the circuit and function with the necessary components to fulfill the processes being executed (attached at the specific functions within the flowchart) would better explain it all... That would simplify the matter greatly.


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## Technologic (Jul 20, 2008)

fugdabug said:


> Electricity from traction pack comes into... electricity for controller system comes into... from there it goes to... pretty 'paint-by-number' picture... but that is what I am having trouble wrapping my head around at this time... Maybe if I can find the proper solvent to wash down the Kelly board and clean away the masking I can then trace and get a better idea of the flow of current with in the system devised by them... to fill in the 'paint-by-number' sequence. A flow chart of the circuit and function with the necessary components to fulfill the processes being executed (attached at the specific functions within the flowchart) would better explain it all... That would simplify the matter greatly.


A flow chart of a circuit with functions explained would probably take longer than a working circuit 

As far as I can tell, my short comings are going to be in the PWM controlling portion, as I can design the rectification circuits quite easily. I'm very curious what IGBTs or MOSFETs people are planning to use for the output circuit. I like the idea of paralleled MOSFETs still, because there are such reliable cheap ones out there, many with free samples.

I also painfully have no experience with choosing IGBTs or any issues associated with them (loop feedback? signal distortion? heating?)


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## Georgia Tech (Dec 5, 2008)

ga2500ev said:


> Folks,
> 
> The software isn't the issue. In fact you don't really need software at all. It's a luxury. A simple 555 PWM circuit like this one:
> 
> ...


Couple of thoughts here:
1) How would you do the current limit?
2) Is driving an IGBT as simple as a stiff high current totem pole driver? I thought there was more to it than that. This is how to drive MOSFETS but I thought IGBTs were a little more involved...


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## fugdabug (Jul 14, 2008)

"Now the chances of getting all of this gift wrapped is pretty slim Fudabug. Anyone who takes the time to package up everything is going to want to get a return on that investment."

Yeah that is the problem with this world. "what's in it for me..???"... I think there have been mega-amounts of folks on this site and others that have openly shared their tech expertise, their time, their efforts and understandings... were they 'paid'... probably ten-fold by the improvements others have been able to make and then build on... call me an overly-simplified optimist, but at a time when a lot of folks are in need of some folks to provide information in a rather dismal economic atmosphere and when this nation needs to spark a new tech revolution from the ground up... all we hear is "what's in it for me..???"... well at that rate a grave for all of us...
Sorry I don't buy the "what is the payment?" crap argument... I asked a simple thing: an open-source (available to all) design. If you have something that works and will work for a 72-168VDC system DC controller... then prove it, and ask for a small amount for the schematics... that simple. I am looking for the next best 'mousetrap' that will allow all of us to create the revolution in transportation we need at this time! And not for personal profit...(not for my personal profit... for the commonwealth!)


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## Georgia Tech (Dec 5, 2008)

fugdabug said:


> "Now the chances of getting all of this gift wrapped is pretty slim Fudabug. Anyone who takes the time to package up everything is going to want to get a return on that investment."
> 
> Yeah that is the problem with this world. "what's in it for me..???"... I think there have been mega-amounts of folks on this site and others that have openly shared their tech expertise, their time, their efforts and understandings... were they 'paid'... probably ten-fold by the improvements others have been able to make and then build on... call me an overly-simplified optimist, but at a time when a lot of folks are in need of some folks to provide information in a rather dismal economic atmosphere and when this nation needs to spark a new tech revolution from the ground up... all we hear is "what's in it for me..???"... well at that rate a grave for all of us...
> Sorry I don't buy the "what is the payment?" crap argument... I asked a simple thing: an open-source (available to all) design. If you have something that works and will work for a 72-168VDC system DC controller... then prove it, and ask for a small amount for the schematics... that simple. I am looking for the next best 'mousetrap' that will allow all of us to create the revolution in transportation we need at this time! And not for personal profit...(not for my personal profit... for the commonwealth!)


If I had the time and money I would LOVE to do it and post all the source code, schematics and Bill of Materials.......this stuff is fun to me, its more of a hobby you would say..


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## Georgia Tech (Dec 5, 2008)

It would be kind of cool sort of the GNU standard or like Linux!!! Free ware is the BEST!!!


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## TheSGC (Nov 15, 2007)

fugdabug said:


> "Now the chances of getting all of this gift wrapped is pretty slim Fudabug. Anyone who takes the time to package up everything is going to want to get a return on that investment."
> 
> Yeah that is the problem with this world. "what's in it for me..???"... I think there have been mega-amounts of folks on this site and others that have openly shared their tech expertise, their time, their efforts and understandings... were they 'paid'... probably ten-fold by the improvements others have been able to make and then build on... call me an overly-simplified optimist, but at a time when a lot of folks are in need of some folks to provide information in a rather dismal economic atmosphere and when this nation needs to spark a new tech revolution from the ground up... all we hear is "what's in it for me..???"... well at that rate a grave for all of us...
> Sorry I don't buy the "what is the payment?" crap argument... I asked a simple thing: an open-source (available to all) design. If you have something that works and will work for a 72-168VDC system DC controller... then prove it, and ask for a small amount for the schematics... that simple. I am looking for the next best 'mousetrap' that will allow all of us to create the revolution in transportation we need at this time! And not for personal profit...(not for my personal profit... for the commonwealth!)


Ok, I'll admit that I will be in it for the money in the long run. In a few years I plan on making EV controllers as a side thing. BUT my business plan has two sides: The mulah and the open-source. I have a design I am working on that should handle 24-72 volts and 60 AMPs continuous. Yes, 60 AMPs is small BUT the design is modular. So you could just add these suckers in parallel for more AMPs. I am building two prototypes and working on the coding and going to see how they work. The higher voltage version will use 250 volt MOSFETs instead on the 100 volt ones I have now. Total cost for Parts for 24-192 volts: $38 per unit.

Here's a schematic for your pleasure. The current sensor is mislabled at the moment, it supposed to be a 100 AMP hall effect.


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## Tesseract (Sep 27, 2008)

fugdabug said:


> ... I asked a simple thing: an open-source (available to all) design. If you have something that works and will work for a 72-168VDC system DC controller... then prove it, and ask for a small amount for the schematics... that simple....


Google Is Your Friend:

http://www.evdl.org/lib/mh/index.html

Mark Hanson's design is a reasonable starting point. It could use much beefier and isolated gate drive but it is microprocessor controlled and even implements desat detection. Also, he provides the firmware for the microcontroller.


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## fugdabug (Jul 14, 2008)

Georgia Tech said:


> It would be kind of cool sort of the GNU standard or like Linux!!! Free ware is the BEST!!!


Hmmmm... could publish it under the Gnu license... which by the way allows you to charge for the work... all I was saying is that if you keep it down to an 'everyman' affordable level... it is covered with you as the author and it is still listed open-source, and you can still collect fees for the plans... so it is a win-win... However it does allow others to modify or change the design along the way, as long as a change-log is included, so it then becomes an evolving process.


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## Zanthic (Jul 2, 2008)

I have been thinking more about my idea of building separate modules, each limited to 50 Amps and although I normally would throw a micro into everything I build, I think the circuit would be faster and better suited to be a simple current sense comparator for current limiting. I haven't done the math but I am thinking the A/D input on most micros is just too slow. The other advantage to each module taking a simple on/off input is that you can use one micro to coordinate the firing of each one and instead of just paralleling them so they are all controlled at the same time you could have a much smoother switching currents by staging them...you heard it here first, a "pwm staging controller" 
Take a look at the following graphs. The first one would be 10% power with all (8) modules turned on and off at the same time creating a 400 amp pulse (ouch) as opposed to Fig 2 where each module is only on for 10% of the time but they each take a turn so maximum on and off current is 50 Amps.
The remaining 3 figures show three different ways of achieving 35% total power, either through using 4 modules (Fig 3), all 8 modules (fig 4) or 3 modules (Fig 5) with the minimum amount of switching. I guess the trade off is that Fig 4 divides the heat load amongst all 8 but at the expense of more switching.


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## ga2500ev (Apr 20, 2008)

Zanthic,

The modular idea seems to parallel the BatPack concept:

http://www.redrok.com/ev.htm

but instead of modules limited by current as you specify, the BatPack modules package batteries in voltage groups that are switched in and out.

I'm still trying to figure out how the seeming overcomplexity of a module based system helps the situation. The BatPack makes some very clear arguments that makes sense to me:

1) Cheaper MOSFETS because of lower voltage requirements.

2) Much slower switching speed resulting in less energy losses.

3) The modular design makes the controller more failsafe because there isn't a single point of failure.

But other than sizing I cannot yet see the advantage of current limited modules. Everything in a PWM controller scales well. So the same design can be used for a 12V 50A controller as a 168V 600A controller. Only the MOSFETS/IGBT (and driver), current detection, and caps needs to be upgraded.


We're like the blind men examining the elephant. Each of us sees the problem from a different perspective. The software people, such as myself, think that the control system is no problem as long as the drivers are taken care of. The hardware folks can see the power electronics clearly, but have issues with the control systems.

One needs to be a well rounded engineer to fully understand the whole concept.

I still feel that the modularity needs to be in the drive systems. I'd like to start with a single IGBT module for simplicity, then move to MOSFETs for efficiency.

My goal right now is to put together a robust, discrete, current limited driver that holds everything together. Discrete because I know that being beholden to a particular chip that may become made out of unobtanium is bad news. What I've gotten so far in the design is this:

1) It needs to be a totem pole.

2) The drive outputs need to be current limited. TheSGC says the max drive current is 8A. Tesseract has thrown out numbers upwards of 30A depending on the switching speed.

3) Personally I still think that hardware deadbanding is the simplest way to ensure that both halves of the totem pole are not switched on at the same time. A 74HC14 and a handful of discretes is all that is needed to delay switching pulses.

4) Since high current pulses are needed at the switching edges, The power supplies that the totem pole is switching needs to have hefty low ESR caps charged up. A question: should the caps and the power supply have a steering diode between them to ensure that the supply does not get drained by the pulse?

Once the driver in the middle is straight, the rest of a simple controller is pretty straightforward. Microcontroller on the controller side, big IGBT and caps on the motor side.

ga2500ev


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## fugdabug (Jul 14, 2008)

Tesseract said:


> Google Is Your Friend:
> 
> http://www.evdl.org/lib/mh/index.html
> 
> Mark Hanson's design is a reasonable starting point. It could use much beefier and isolated gate drive but it is microprocessor controlled and even implements desat detection. Also, he provides the firmware for the microcontroller.


Innerestin'... I remember bookmarking this in my searches online for a basic DC motor controller... I hadn't gone back to it.


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## Zanthic (Jul 2, 2008)

ga2500ev, I actually don't see one as being better than the other, just different, both with potential pros and cons. The parallel modules as I have suggested are not more complex, all they are is a current limited driver. What is missing from the BatPack description is the current limiting part, he still needs some sort of method of limiting current on *each* of his modules. In fact, I would suggest that the exact same module design could be connected either in series (BatPack) or in parallel (my design). Obviously some consideration would have to be given for maximum voltages etc. The key consideration in either design comes down to fast current limiting. You should be able to short the motor terminals and run the battery dead without having your controller smoke. Any extra cost in a modular design would be well worth it to have a bullet proof controller.

One thing I don't understand is how the BatPack is doing speed control as it appears you have to have a minimum of one pack fully on and the switching is between packs, not pwm speed control. 

As far as the discrete driver circuitry goes, whenever possible I will always take an off the shelf, integrated solution over building discrete. There is so much more engineering that goes into these devices then meets the eye that there is just no point in re-inventing the wheel. The small risk in a device becoming obsolete is not really a concern because not only can it be replaced with a small effort, obsolete parts have a tendency of staying around for many, many years. And, there is often an upgrade path to compatible parts.

I think the bottom line is that there may not be a "fits all" solution but the discussion is good and I think everybody is learning something, I know I am!


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## fugdabug (Jul 14, 2008)

WOW! we have people on subject and talking particulars and thinking!!! Now that let's see what we can put together... this is good!
And it is in language that can be researched... I love it!

MORE!!!


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## TheSGC (Nov 15, 2007)

My classes end this week and I am picking up an oscilloscope from school to borrow until February so I can work on this module idea. 

So this is what I came up with: each module is 60 AMPs continuous and each uses 4 MOSFETs, a PIC controller and a hall effect current sensor. This keeps the cost to about $40USD a module without bulk purchasing, so it would probably be $30-35USD when purchasing the parts for multiple modules.

I have gotten quite good at programming the PIC18F2480 in Great Cow Basic and then smoothing anything out in Assembly. 

This is what my test modules will consist of: 4x IRF540N MOSFETs, PIC18F2480, UCC37322 MOSFET Driver, and a Tamura 600 AMP hall effect sensor. 

I don't have the hall effect sensors my design called for, but this should work fine because its just a 0-5 volt sensor and all that would need changing is the A/D code. I also and scrounging around for a few high amp diodes and I have found a few that should work for this proof of concept protoboard test. I plan on making two of these as test modules. I have all these parts in my possession so it's not costing my anything at the moment.


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## Harold in CR (Sep 8, 2008)

This thread is getting VERY interesting. Good luck with your project.


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## Zanthic (Jul 2, 2008)

TheSGC said:


> each module is 60 AMPs continuous and each uses 4 MOSFETs, a PIC controller and a hall effect current sensor.


I'm curious to know if you're worked out how fast your circuit can respond to an over current situation? I guess the next question would be, how fast does a circuit have to respond in order to protect itself?


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## TheSGC (Nov 15, 2007)

I am looking through the data sheets to see if the A/D is fast enough. If not, I will make a comparator setup that is it parallel to the A/D so if it does over current too fast for the PIC, there will be a faster PWM disable. 

I also am derating the components about 50%, so each MOSFET will be using 15 AMPs continuous, when in reality they can take 33 AMPs continuous a piece. It should be a decent safety margin, and if it works out really good, adjusting to a slightly higher amperage would be as simple as changing a few lines of code. 15A x 4 = 60 AMPS, but it could be changed to like 20A x 4 or even 25A x 4 if desired. But I'll start low for now.


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## ga2500ev (Apr 20, 2008)

Zanthic said:


> ga2500ev, I actually don't see one as being better than the other, just different, both with potential pros and cons. The parallel modules as I have suggested are not more complex, all they are is a current limited driver. What is missing from the BatPack description is the current limiting part, he still needs some sort of method of limiting current on *each* of his modules. In fact, I would suggest that the exact same module design could be connected either in series (BatPack) or in parallel (my design). Obviously some consideration would have to be given for maximum voltages etc. The key consideration in either design comes down to fast current limiting. You should be able to short the motor terminals and run the battery dead without having your controller smoke. Any extra cost in a modular design would be well worth it to have a bullet proof controller.


No disagreement with the bulletproof current limiting in any design. The question is how to do it.

With the traditional PWM the PWM cycle simply gets cut short. No power to the motor, no overcurrent to worry about.

The BatPack can go it one of two directions. The first is the same as the PWM above: simply cut out the switch. A second idea is to bump the voltage to the next level. The additional voltage will cut the current requirements. The problem is that you get a bump in RPM even though the pedal hasn't changed position.

With the modular controller concept you get a blend of both. You can keep adding modules until the current requirement is met. Or if all the modules are at max current, you have to cut the PWM cycle short.

The real question is what is the right behavior in a realistic overcurrent scenario. Think 25% grade, moving slowly, towing a boat, starting from a standing start.

The PWM controllers will 'slip' right? Even though it's providing high voltage pulses, the on time of the pulses will be cut short because of the overcurrent condition, limiting the maximum average voltage to the motor. I hope I have this right.



> One thing I don't understand is how the BatPack is doing speed control as it appears you have to have a minimum of one pack fully on and the switching is between packs, not pwm speed control.


It operates like a contactor or rectactor controller. PWM + the motor generates an average voltage based on the length of the pulses. The motor acts as low frequency filter. So a 144V pack PWMed at a 20% pulse rate will present an average voltage of 144V * 0.2 = 28.8V to the motor. As the motor RPM is tied to the voltage the longer the PWM pulse, the faster the motor spins.

The BatPack on the other hand switches in combinations of subpacks to achieve the requested voltage. So imagine that we have 6 BatPack modules: 2 12V, 2 24V, and 2 36V modules totaling 144V. The accelerator pot can select voltages in 12V increments (i.e. 12V, 24V, 36V, 48V, 60V, 72V, and so on up to 144V) giving 12 different discrete voltages that can be applied to the motor instead of the 256 or 1024 that PWM offers. At any voltage setting at least 2 different subpack combinations can be used to create that voltage. The voltages of the possible subpacks are sampled, and the strongest voltage subpack set is selected to be applied to the motor for the next cycle. Rinse and repeat. So for example if you need 60V you can select one of the 36V subpacks and one of the 24V subpacks. The strongest two are switched in for that 60V cycle, the next cycle the subpacks are resampled and a new pair is selected. Usually that would be the pair that was idle for the last cycle because they were unloaded the previous cycle.



> As far as the discrete driver circuitry goes, whenever possible I will always take an off the shelf, integrated solution over building discrete. There is so much more engineering that goes into these devices then meets the eye that there is just no point in re-inventing the wheel. The small risk in a device becoming obsolete is not really a concern because not only can it be replaced with a small effort, obsolete parts have a tendency of staying around for many, many years. And, there is often an upgrade path to compatible parts.


There have been too many times that I've built with a specialized solution and then suddenly the required parts are unavilable. It's one reason I never use anything from Maxim for example.

I'm exactly the opposite. I would rather know the engineering and be able to build a subsystem from common components than to be held hostage to a part I can't find.

Valentine used a simple totem pole in his sample controller in his book. I don't think there's anything magic about it other than making sure that both parts are not switched on at the same time.



> I think the bottom line is that there may not be a "fits all" solution but the discussion is good and I think everybody is learning something, I know I am!


As am I which is why I keep these types of threads going. Since there isn't going to be a one size fits all we need to explore modular subcomponent options so that someone who wants a 555 timer with a specialized driver and an IGBT can put that together just as easily as someone who wants a microcontroller based BatPack using totem pole drivers with MOSFETs. So we need to get the principles down instead of focusing on a singular packaged solution.

ga2500ev


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## ga2500ev (Apr 20, 2008)

TheSGC said:


> I am looking through the data sheets to see if the A/D is fast enough. If not, I will make a comparator setup that is it parallel to the A/D so if it does over current too fast for the PIC, there will be a faster PWM disable.


The A/D is not fast enough. PICs with an internal comparator are fast enough. So you'd have to gate the comparator output with the PWM signal.

Another possibility is to generate an interrupt when the comparator trips and zero the PWM until the next cycle. Personally I have issues with trusting software alone to do the job. Especially when adding a single AND gate can solve the problem externally.


> I also am derating the components about 50%, so each MOSFET will be using 15 AMPs continuous, when in reality they can take 33 AMPs continuous a piece. It should be a decent safety margin, and if it works out really good, adjusting to a slightly higher amperage would be as simple as changing a few lines of code. 15A x 4 = 60 AMPS, but it could be changed to like 20A x 4 or even 25A x 4 if desired. But I'll start low for now.


Excellent engineering practice.

ga2500ev


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## TheSGC (Nov 15, 2007)

ga2500ev said:


> The A/D is not fast enough. PICs with an internal comparator are fast enough. So you'd have to gate the comparator output with the PWM signal.
> 
> Excellent engineering practice.
> 
> ga2500ev


I think I have to upgrade to the PIC18F4580 because it does have an internal comparator, so I'll use that along with the A/D. I want to use the A/D so I can create a monitoring program and have it display the current, throttle position, and any errors to a serial LCD.

I have finals this coming week so I am booked up, but I will be cleaning up my workbench and getting the prototype parts together and picking up a scope.


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## Zanthic (Jul 2, 2008)

ga2500ev said:


> With the traditional PWM the PWM cycle simply gets cut short. No power to the motor, no overcurrent to worry about.
> ga2500ev


I am thinking about this a little differently. Each module contains the comparator circuitry to limit the maximum (and therefore average) current to whatever, say 50 amps. The PWM signal is relatively slow, say 15Khz but the comparator "chopper" circuit divides that up into an average current and would run significantly faster giving each portion of the on time of the pwm signal a sub-on/off timing.


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## blackpanther-st (Apr 4, 2009)

fugdabug said:


> "Now the chances of getting all of this gift wrapped is pretty slim Fudabug. Anyone who takes the time to package up everything is going to want to get a return on that investment."
> 
> Yeah that is the problem with this world. "what's in it for me..???"... I think there have been mega-amounts of folks on this site and others that have openly shared their tech expertise, their time, their efforts and understandings... were they 'paid'... probably ten-fold by the improvements others have been able to make and then build on... call me an overly-simplified optimist, but at a time when a lot of folks are in need of some folks to provide information in a rather dismal economic atmosphere and when this nation needs to spark a new tech revolution from the ground up... all we hear is "what's in it for me..???"... well at that rate a grave for all of us...
> Sorry I don't buy the "what is the payment?" crap argument... I asked a simple thing: an open-source (available to all) design. If you have something that works and will work for a 72-168VDC system DC controller... then prove it, and ask for a small amount for the schematics... that simple. I am looking for the next best 'mousetrap' that will allow all of us to create the revolution in transportation we need at this time! And not for personal profit...(not for my personal profit... for the commonwealth!)


I agree with this! 
It has been working in the Linux community for years and Linux has come a long way in the past few years. I am using it now as I write on this forum; but fugdabug is probably right in that it won't all come from one person; most involved opensouce projects draw on the talents of a large community of people with a common interest. Granted this project is a lot simpler than a complete operating system and the thousands of free programs which run on it.


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## fugdabug (Jul 14, 2008)

THAT is why my other OS is LINUX... (Debian core)... the hope to make available that which will better the whole... It is the science fiction I dreamed of as a child... and that is no bullcookies!


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## ga2500ev (Apr 20, 2008)

fugdabug said:


> THAT is why my other OS is LINUX... (Debian core)... the hope to make available that which will better the whole... It is the science fiction I dreamed of as a child... and that is no bullcookies!


The open source 144V controller project over on ecomodder seems to be as close as you're going to get. Check out the 1100+ post monster here:

http://ecomodder.com/forum/showthread.php/paul-sabrinas-cheap-144v-motor-controller-6404.html

ga2500ev


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## blackpanther-st (Apr 4, 2009)

ga2500ev said:


> The open source 144V controller project over on ecomodder seems to be as close as you're going to get. Check out the 1100+ post monster here:
> 
> http://ecomodder.com/forum/showthread.php/paul-sabrinas-cheap-144v-motor-controller-6404.html
> 
> ga2500ev


I just checked this out last night when I found your link here, about 3-4 hours, I read the whole damn thing! This is a truly impressive open source project and they are really on to something. there is a lot really good talent going in to this one and it shows. they are just about reedy to test version two. the first one was successful but eventually failed, apparently due to an improper start up and shut down sequence and a few weaknesses in the system. version two has become much more developed. I am going to have to join the ecomodder site so I can see his actual circuit designs.

I am thinking about seeing if his design might be convertible to an IGBT controler? I don't know though and prototyping could easily get more expensive than getting a ready made unit.


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## TheSGC (Nov 15, 2007)

I am slowly working on an IGBT controller using CM600HA modules. If things go well I might have a prototype later this summer along with a full schematic.


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## tj4fa (May 25, 2008)

This guy David Arthur made a Pulser (controller) years ago for about $25-.

http://www.motherearthnews.com/Gree...Amazing-75-MPG-Hybrid-Electic-Car.aspx?page=2

From page 2 of the article:
[h3]


> Growing Pains


[/h3]


> Any project fresh off the drawing board has its share of problems, and the Opel hybrid was no exception. When David pressed the accelerator for the first time, he got a 300-amp surge which melted his relays. So he searched his graduate texts for the answer ... and finally found it in-of all places-an old high school physics book: A pulser was necessary to "chop" the current flow and prevent a heavy initial draw to the drive motor.
> As Dave explains it, "The motor will always have full voltage and full current, but the pulser makes it 'think' the voltage and amperage are cut down to about 1/4 of what's actually available. With this gadget-which is simply a combination of a reworked car generator and an old fan motor-I can keep the draw within limits and effectively control the car's acceleration ... without sacrificing the maximum current or voltage that's necessary for high-speed driving. I could have achieved the same results with a commercially available FCR control ... but one of those units would have cut my power slightly, and cost in the neighborhood of $800! I can build my own device for about $25, and I can fix it myself if it breaks!"


Now how could he do that?


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## Harold in CR (Sep 8, 2008)

He used the generator and cut some of the lead bars out going to the commutator. This makes the "Chopper" he talks about. The story is still available on MENews mag.

This is where I was going with my electric Mazda pickup, back in the day ???


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## grayballs (Aug 27, 2008)

tj4fa said:


> This guy David Arthur made a Pulser (controller) years ago for about $25-.
> 
> http://www.motherearthnews.com/Gree...Amazing-75-MPG-Hybrid-Electic-Car.aspx?page=2
> 
> ...


 
I used one of these for motor control on my 2nd Tadpole,,, 'not the most comfortable controller, but acceptable,, or should I say, an improvement over the Carbon Pile Resistor, I used for my first.


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## tj4fa (May 25, 2008)

grayballs said:


> I used one of these for motor control on my 2nd Tadpole,,, 'not the most comfortable controller, but acceptable,, or should I say, an improvement over the Carbon Pile Resistor, I used for my first.





Harold in CR said:


> He used the generator and cut some of the lead bars out going to the commutator. This makes the "Chopper" he talks about. The story is still available on MENews mag.
> 
> This is where I was going with my electric Mazda pickup, back in the day ???


Hmmm...this is interesting and brings up a couple questions.

Can you use a 25Kw 380-800HZ (determined by RPM) AC output aircraft generator that has commutator rings as an EV traction motor and can some of the bars/poles be cut/deactivated to produce the chopper effect internally in the generator head itself like the one shown in the photos below?

Please forgive my ignorance-I'm not smart on the motors/electronics stuff yet.

This unused aircraft generator was built for a post-WWII era F-86 jet.


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## MalcolmB (Jun 10, 2008)

tj4fa said:


> This guy David Arthur made a Pulser (controller) years ago for about $25
> 
> Now how could he do that?


I'm not saying this is how he did it, but this is one way: http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1875

Malcolm


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## grayballs (Aug 27, 2008)

I cut the commutator end off of a heavy auto starter, drilled the shaft and fit that to the shaft of a small DC fan motor. I then soldered every other bar together and wired the traction motor thru an opposing pair of brushes. Using a small rheostat to control the speed of the fan motor, effectively 'chopped' the power supply to the traction motor. 
As I remember it, the faster the fan motor, the smaller the 'pieces', so the slower the traction motor,,,,,,,,,,,LONG time ago


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## Harold in CR (Sep 8, 2008)

Just ran across this idea this morning. Supposed to be able to deliver up to 1200 AMPS, at high voltage ??? Got to do some more looking into this . 

http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1875


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## JRP3 (Mar 7, 2008)

Harold in CR said:


> Just ran across this idea this morning. Supposed to be able to deliver up to 1200 AMPS, at high voltage ??? Got to do some more looking into this .
> 
> http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1875


Did you happen to see it 2 posts above yours


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## Harold in CR (Sep 8, 2008)

Time zone difference, EH ??? AND, where do you get the smileys ???


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## JRP3 (Mar 7, 2008)

Harold in CR said:


> AND, where do you get the smileys ???


They don't show up for you to the right in the reply window?


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## Harold in CR (Sep 8, 2008)

All I get to the right is, Switch Editor Mode and Increase -decrease size ???

Not important enough to highjack the thread.


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## blackpanther-st (Apr 4, 2009)

Harold in CR said:


> All I get to the right is, Switch Editor Mode and Increase -decrease size ???
> 
> Not important enough to highjack the thread.


That's it hit the switch editor mode and they should show up.


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