# Blackpanther_st's home brew DC motor controller.



## blackpanther-st (Apr 4, 2009)

OK so I have a few things in the works as I do my EV conversion for the Fiero Electro; as I work on this I am also doing a documentary on the conversion process, which I will begin posting somewhere in the near future. 

The other is the article of this forum thread, which after the frustration of not seeing any verifiably reliable motor controllers in my price range and powerful enough for my conversion, I have decided to join in with the few others I have seen attempting their own motor controllers. 


I have been following MpaulHolmes progress with his motor controller at Ecomodder, *Paul & Sabrina's cheap 144v motor controller*


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


Seeing what is happening with his project has been the most influential in my decision to do my own.


So this is what I am starting with:













Though they look like IGBT's and are made by tPowerex, they are not. IGBT's, those are actually power FET's rated at 300A each and 1000V there model # is KS621K30 New these are about $300 a piece! But I got these on Ebay for about $90 for all four. I tested each one individually at 12V and 5A and they all work as I would expect them to. 


One thing I noticed in the data sheet for these FETs is that they have a natural tendency to balance current load, unlike IGBT's which have a natural tendency to become unbalanced.




For size reference, the heat sink is 8” x 12” with 1” fins and a 1/4” backing plate. The buss bars are 3/4” square aluminum. 


One thing you may notice in the photo, that I am doing differently than others is that I am not connecting the B+ and M+ cables to the same point on the positive buss; instead I have one at each end, so that B+ and B- are on one end of the controller and M+ and M- are on the other. The reasons I chose to do this are one, it eliminates the possibility of the freewheeling diodes from becoming disconnected from the loop while power is still being applied to the motor in the event of a loose connection. The other reason is that it will make the connections less crowded. 


Plans not yet implemented.


The positive buss will be thermally connected, but electrically isolated from the heat sink
freewheeling diodes will be thermally and electrically connected to the positive buss.
Capacitors will be in two banks on either side of the FETs and positive buss.
I plan to use copper foil with a mylar insulator to connect the capacitors to the B- and positive busses. A narrow section of copper foil will also connect M- to the freewheeling diodes. 


The control section;
I have never worked with microcontrollers before, but I found the µCHAMELEON though rather pricey seemed to have what I wanted in a relatively easy format to use. And I do mean relatively, from my experience. 


The µCHAMELEON came with a test application which allows you to run some basic functions from your computer over USB without having to program anything. Switching on and off each of it 18 IO pins from the application seemed to work fine as did measuring 0-5V input from the 8 pins which accept A to D input also all 18 pins were able to read IO state of connection to pin.


Now here is where I could use some help; while the programming for this seems relatively simple compared to programming I have dabbled with in the past, I have never dealt with communicating with hardware as far as microcontrollers are concerned, and I don't know how to send the strings to the device? I know that this is bacicly the first step in learning these things , but I can not find any documentation on this which is helpful to me. I am hoping that someone here can help get me started in the right direction.

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Correction ! 

As ga2500ev pointed out to me they are darlingtons, not FETs as I stated above; I had read the data sheet a few weeks ago and I must have gotten it mixed up with something else I was looking at. The power specks however are as I stated.


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## MPaulHolmes (Feb 23, 2008)

Awesome! You're going bigtime! I've never used the uchamelion before. The only microcontroller programming i've done is with the ATMega8. I a little confused by the phrase "don't know how to send the strings to the device". I think you need a pwm output from a microcontroller that leads to the input of the mosfet driver, which leads to the gates of the HUGE AWESOME mosfets. You can always just use one of my ATMega8's pre-programmed. It could be like a black box. They are VERY expensive, however. We're talking like $3!


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## ga2500ev (Apr 20, 2008)

I took a look at the data sheet for the part and it's not a power FET. It looks like it's a humongous Darlington power module. The problem is that the voltage drop is going to absolutely kill this project. The saturation voltage is 2.5V. That means that you'll lose 2.5V*300A = 750W to heat. It will severely impact your range and test your heat dissapation skills. This is about double the saturation voltage of an IGBT, which many avoid because of excessive heat.

The second problem is the turn on/turn off times are very slow, on the of 3 uS. During this transistion almost all of the power through the device is converted to heat.

It's only $90 and it seems like you have it all together. But I'm pretty sure that at some time in the future you're going to want a much more efficient power section.

ga2500ev


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## Watt-a-mezz (May 20, 2009)

Hello Blackpanther & MPaul, I have been following along ,maybe learning something new. I do not think I will be building controllers, but if you develop yours(MPaul) to where you would like it to be, would I be able to purchase one? (I am one of the nervous kelly owners) Keep up the good work! Take Care, Watt


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## blackpanther-st (Apr 4, 2009)

MpaulHolmes, 
From what I understand, you can send the uchamelion individual command strings one by one, (as in being run by a host computer), or an entire program can be sent, to run on the uchamelion it self. The test application I mentioned runs on the host computer and sends individual commands, but the communication is handled from within the program. I need to learn how to do this manually. From what I have read you can use something like tellnet to do this.


My biggest disappointment with this thing is the lack of adequate documentation, including user forums.
I do know that the uchamelion has the PWM outputs I need; more than enough, I believe you can configure up to 8. I am considering using one to drive the original tachometer gage and speedometer in the fiero, without using the original ECM; my controller would essentially replace it.


I am still not sure if the uchamelion really fits what I want to do. I had thought about the Megas befor I got the uchamelion, but the learning curve looked like it would be steeper, I am not so sure now, at least there is information on the Megas. I was also taking in to consideration that I would need some sort of hardware interface to program the Mega as I understood the situation, is that correct?


I appreciate the offer for a preprogrammed one, but I really want to lay out my own functions, routines and parameters.


Moderate power testing!
In repply to ga2500ev, you are correct, They are darlingtons FETs as I stated above; I had read the data sheet a few weeks ago and I must have gotten it mixed up with something else I was looking at. The power specks however are as I stated. 


I saw what you had mentioned about the saturation voltage before, and yes I was concerned about it, but most of what I have read stats IGBTs as being nearly 2V for saturation and I was already leaning towards IGBT's for the voltage head room. 


So today decided to test these under a little more power, and see just how bad the saturation would be in real life. As it turns out , it is not so bad after all. 


In my test I used my battery tester and bypassed the solenoid to avoid any induction spikes, ( I don't have any freewheeling diodes yet.) the tester draws about 85A when cold and drops to about 60A when it is hot; about a 10 second load test. 


Two of the four darlingtons At 12v system and 1.6A of base current, (5V suppled through 2ohm power resistor) and they easily handled the 85A draw and I held the gates on until the load current droped to 60A


During the test I had a voltage meter across the C and E of the darlingtons, to measure saturation voltage. At the initial 85A, saturation voltage was just barely 2V and at 65A saturation voltage was below 1.5V and falling. 


With the light weight of the Fiero I only expect to draw about 120A on flat land for normal driving at 45 MPH, so 65A on two out of the four darlingtons is realistic for average load they will see in the car. That works our to a saturation loss of under 200 Watts under average load. 


Of course acceleration losses will be much higher, but I am not nearly as concerned about that as I am the average load loss; so long as It can deliver some serious Amps when I need them. 


The 3 u second transition time however may be a bit more of a problem than I initially realized; I am probably going to have to clock down my PWM cycle time.


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## Zemmo (Sep 13, 2007)

This is a very interesting controller you are coming up with. I will be following it with interest. I also thought that I would point out, that the speedometer gets its signal from the transmission. I don't know if it required an ECU to make it work, but it gets its signal from the tranny.

This is the basic amps that I draw on level ground at a constant speed in my Fiero. Every car seems to be different and even with the same equipment; a different car pulls different amps. So this is interesting info just in general and give you a frame of reference (my car runs at 120 volt and all measurements are from the battery side).

25 mph (2nd gear) is usually about 25 to 35 amps

35 mph (3rd gear) is usually about 40 to 55 amps

45 mph (3rd gear) is usually about 65 to 85 amps

55 mph (3rd gear) is usually about 100 to 110 amps

65 mph (4th gear) is usually about 125 to 135 amps

Under basic acceleration, I only pull 150 amps. Thats a nice easy acceleration. If traffic is heavy, I will pull 200 amps. After about 200 amps, it doesn't really feel like I get more acceleration even if I pull 300 amps. I think 300 amps feels about the same as 200 amps acceleration wise (once your past 25 mph). If I am accelerating onto the interstate then I am usually pulling 250 or more.

Hope this helped with your designing and planning stage.


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## blackpanther-st (Apr 4, 2009)

Zemmo, thanks for the numbers on your fiero. That definitely is a help, seeing how it breaks down in each gear / speed range. 

I must say that you are getting much better readings than I was expecting, and I will be running at 144, so my current should be even lower, if all else is the same. I think that the choice of motor has a lot to do with it, so I could be way different. Can I ask what you are running for a motor? I am going to be using a 9" GE forklift motor. Jim tells me it should be equivalent to a warp 9 for performance curves; they are built almost identically except for cosmetic changes and GE's lousy tapered shaft


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## Zemmo (Sep 13, 2007)

I am using an Advanced DC 9" motor. Its about the same as a Warp 9, but the power ratings are rated just a little under the Warp. I don't know if those ratings are independently tested, probably not. That motor is connected to a 4 speed trans with the clutch. You can check out my website for tons of details.

I would love to go to 144 volt. All of my equipment can handle it. It is just the Fiero wouldn't like it much with the Lead Acid batteries. She is pretty heavy as it with the 20 Six Volt batteries. I am still pondering the next pack being LiFePo4 and doing the 144 Volt. Get better acceleration performance (less weight and more volts) and maybe buy more mileage.


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## brdriver (May 26, 2009)

old brother:
through your discribing,i advise you choose other solution,use lowe voltage and large current mould to drive.ok?
for example:Bangrong technology's product can suit your application on the driver.ok?
do you think your current mould is 1000V300A,although its price is cheap,but your machine is not feel its well point.futue you need more the kind product,it is not be provide for you.right?
other, your current mould's vol. is too large to fix easy,and its weght is effect your all run efficiency,ok?
please think its solution again!
best redards!
sober'r in shenzhen of china.


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## blackpanther-st (Apr 4, 2009)

brdriver

300A 1000V is the ratings for each darlington transistor, there are four of them, 1200A capability, though I will be limiting at 750A - 1000A max. My system voltage will be 144V which is ideal for my motor and vehicle. the controller should be able to handle more volts providing I use capacitors that can handle it, but for my application I don't see the need for anything higher; this is already in the entry level Zilla range


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## MPaulHolmes (Feb 23, 2008)

Hey Blackpanther! These list the ESR, and have worked very well for me. There's lots of variations to choose from:

http://www.panasonic.com/industrial/components/pdf/ee163_ed_ts_dne.pdf

Those look like pretty good diodes. You also might consider either:

http://www.st.com/stonline/products/literature/ds/10179/stth6002c.pdf, which has a lower voltage drop, but still has the 200v problem... or...

http://www.fairchildsemi.com/ds/RU/RURG8060.pdf, which are rated at 500v, but have a bit higher of continuous amp rating and higher voltage drop. 

Awesome job! I think those beasts you have will carry the current just fine. And I think that uchamelion will work really well too from how you described it.

Oh, And when the controller is working well, I'd be happy to make one for anyone that wants one! ya! It might be a good way to supplement my crappy income at Sylvan. hehe.


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## brdriver (May 26, 2009)

haha...
i am pleasure from your so large power.especial is your continuous current get 1200A.i think your motor is not get so larde current.normal EV of personal application has 50-200KW,and its work voltage is 144-288V.if you choose the kind,it is only add your costly on drive,other its vol. is too large to fixing easy to your actual environment.
ues your indeed power,you will pay for active expense!
let you know Bangrong technology enterprise product,maybe it can hel p you..
best regards! 



blackpanther-st said:


> brdriver
> 
> 300A 1000V is the ratings for each darlington transistor, there are four of them, 1200A capability, though I will be limiting at 750A - 1000A max. My system voltage will be 144V which is ideal for my motor and vehicle. the controller should be able to handle more volts providing I use capacitors that can handle it, but for my application I don't see the need for anything higher; this is already in the entry level Zilla range


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## blackpanther-st (Apr 4, 2009)

MPaulHolmes said:


> Hey Blackpanther! These list the ESR, and have worked very well for me. There's lots of variations to choose from:
> 
> http://www.panasonic.com/industrial/components/pdf/ee163_ed_ts_dne.pdf
> 
> ...


Paul, lets see where this heads  First I need to learn how to get something programed on the uchamelion, and get a PWM signal out of it for starters. 

If all goes well and this thing performs as is should, I could be interested in doing something together with you, making these for others who don't want to start from scratch. Perhaps if you do the control boards and I do the power section and ship them off to you, then you add the control section and close the box; we could have a finished product. That could help each of us out, and give our fellow EVers more to choose from. 

To be sure I want to encourage you with your own project! I think you have done a fantastic job with it, especially considering the experience you started with. 

Even though mine is in the very early stages I can see that these will be two very different animals with different characteristics for people to chose from. 

One thing I feel is worth mentioning to you about open source, is that projects being developed in it are a bit like a band; it is very easy for different people to pull it in so many directions, that the original ideas or foundation of the project gets lost! 

Listening to advice is always good, but remember that it is your project, and chose what you feel is best for it. Being open source, if other people feel they want something different, they are always free to branch off and start their own variation. I am mentioning this to you now because I see the beginning of that happening as I follow the progress of your project. I don't want see it get to the point where you feel like your own project has been taken over and is no longer yours.


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## blackpanther-st (Apr 4, 2009)

brdriver, 

I looked up your company and found your controllers, your product # Br18k-144V/342A-3012 is very similar in it's power capabilities to mine, and it is listed as the larger of your pasenger car class controllers. (note the 1000A rating in mine would be the peak rating, leaving 200A for head room) 

It looks like it could be a good controller, and I have never seen or heard of your company or products before; I would recommend posting your controller line under the controllers section as a new controller brand available. And please do list your prices! I am sure that there are many who would welcome seeing your option there, rather than criticizing what I am doing here. 

This project is in development for my own use, and is open source for any one interested in using ideas I present here. Are you nervous?  most people don't want to take the time to do this, and would rather get something ready made. I am not one of them and neither is my friend working on his controller version. I for one enjoy creating and using something which is truly my own. 

That being said this is an experimental project; it may not work as expected. In that case I could end up interested in your product, providing you don't piss me off first.


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## Watt-a-mezz (May 20, 2009)

MPaulHolmes said:


> Hey Blackpanther! These list the ESR, and have worked very well for me. There's lots of variations to choose from:
> 
> http://www.panasonic.com/industrial/components/pdf/ee163_ed_ts_dne.pdf
> 
> ...


Cool, Thanks, MPaul. I am more the mechanical type, I have always envied people who could do stuff like that, and seriously I would be happy to have one. Keep up the good work , you may be the future of EV's
Take Care, Watt


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## brdriver (May 26, 2009)

Dear old brother:
through your show some informations,i think your moter would less than 30KW,because your motor is be use in home personal vehicle,so it is not INDEED BE expense on more power to drive.
as Br18k-144V/342A-3012 type controller,it is can drive 18-30KW motor,342A is its continuous current,its peak current gets or over 1128A.you willn't worry its quality.because the controller's actual power is 144*342=49.248kw,so it will complete able to drive the personal vehicle motor.
another,i am pleasure from your ability of create out in old vehicle.the project is suit city development requirement,and all gov. reqest people use EV to go work.and protection environment.
you are a love thounght man,and hard wok for yourself.let me learn follow you!
and i want to know what is your location now,if might,please tell me.when you need the product,i will help you to value all cost.hehe...
my MSN:[email protected]
successfully to you!

best redards!
 


blackpanther-st said:


> brdriver,
> 
> I looked up your company and found your controllers, your product # Br18k-144V/342A-3012 is very similar in it's power capabilities to mine, and it is listed as the larger of your pasenger car class controllers. (note the 1000A rating in mine would be the peak rating, leaving 200A for head room)
> 
> ...


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## CroDriver (Jan 8, 2009)

blackpanther-st said:


> brdriver
> 
> 300A 1000V is the ratings for each darlington transistor, there are four of them, 1200A capability, though I will be limiting at 750A - 1000A max. My system voltage will be 144V which is ideal for my motor and vehicle. the controller should be able to handle more volts providing I use capacitors that can handle it, but for my application I don't see the need for anything higher; this is already in the entry level Zilla range


Could you make it 400-500V and 1200 Amp?


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## brdriver (May 26, 2009)

hehe...
thanks for your ask for.
our product has the kind 400-500v,1200A.of course its continuous current is 1200A.but i am always think your personal vehicle is not get 1200A driver of continuous current.maybe 1200A is your peak current.this is suit actual application of EV home.
please think over again!

successfully to you!
best redards!



CroDriver said:


> Could you make it 400-500V and 1200 Amp?


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## blackpanther-st (Apr 4, 2009)

CroDriver,

I don't see a problem with 500V except that the capacitors would be more expensive. 1200A is right at the limit of these darlingtons with a set of four. I know with MOSFET's, it is recommended to leave some head room on the amperage ratings, so I think it would be good to limit to 1000A. this also gives a little room for error as far as the current limiter goes. 

I have been thinking though, that if this works well, it would not take much to mirror two sides of this with one control board. that would make one fully drag worthy 2000A 500V monster!  

Paul recommended some good caps and freewheeling diodes; ill be ordering those soon along with a few other components. Then I can do some further testing with inductive loads.


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## brdriver (May 26, 2009)

guess your location is in Australia.i am online,MSN:[email protected]
other,i am want to know your vehicle actual reference,max. load,or how speed,what time of continuous,how set battery,etc.
hehe...
let me wait for you on MSN.



blackpanther-st said:


> CroDriver,
> 
> I don't see a problem with 500V except that the capacitors would be more expensive. 1200A is right at the limit of these darlingtons with a set of four. I know with MOSFET's, it is recommended to leave some head room on the amperage ratings, so I think it would be good to limit to 1000A. this also gives a little room for error as far as the current limiter goes.
> 
> ...


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## CroDriver (Jan 8, 2009)

brdriver said:


> guess your location is in Australia.i am online,MSN:[email protected]
> other,i am want to know your vehicle actual reference,max. load,or how speed,what time of continuous,how set battery,etc.
> hehe...
> let me wait for you on MSN.


That's for me or blackpanther?


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## blackpanther-st (Apr 4, 2009)

Mouser came in to day with most of my parts,  and I have done some more testing using a pair of 555 timers for a quick PWM signal. The Darlington transistors seem to be quicker than what some of the concerns were suggesting and I am getting respectable edges on my square waves from them at 12 KHZ, though this is still just with a resistive load; I don't have the freewheel diodes installed yet.

Unfortunately the MOSFET I ordered for the gate driver was on back order, and the undersized one I was using blew last night, so I can't do any good inductive testing with the freewheel diodes until I get another MOSFET.

In the mean time I have been working on the hardware end between all of my other projects.










All those big caps were expensive, I sure hope this MFD works! 


16* electrolytics, each 1800 MFD @ 250 V rating + 8* polypropylene, each 4.7 MFD @ 250 V rating. 

Freewheel diodes are 15* 80A @ 600 V rating, Fairchild ultra fast RURG8060.


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## MPaulHolmes (Feb 23, 2008)

That is a thing of beauty! You aren't wasting any time, are you!? You are going to have some crazy high ripple current capability. Each poly cap contributes 5 amps of ripple current I believe.


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## blackpanther-st (Apr 4, 2009)

MPaulHolmes said:


> That is a thing of beauty! You aren't wasting any time, are you!? You are going to have some crazy high ripple current capability. Each poly cap contributes 5 amps of ripple current I believe.


Yes I believe it is right about 5A of ripple for each and the electrolytics are about 3.5A, it changes with the frequency. 

It has been raining nearly every day for more than 40 days! Iv'e been joking that I should be building an ark and gathering animals instead of building an electric car!

The µCHAMELEON isn't going to work for this though, I believe it only works as a connected peripheral to a host computer, so I may be asking you a few questions soon about the micro prossesors you are using. 

I have been following up on yours and it looks it has realy come a long ways  I think you will be helping a lot of people with having it open source. I am still suprised that your BOM bill is so low for what your controler does.


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## MPaulHolmes (Feb 23, 2008)

well, the BOM just covers the control section, but ya, it is pretty cheap, huh! I'll be here to answer any questions about ucontroller programming. this is exciting! great job!


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## Amberwolf (May 29, 2009)

blackpanther-st said:


> All those big caps were expensive, I sure hope this MFD works!
> 
> 
> 16* electrolytics, each 1800 MFD @ 250 V rating + 8* polypropylene, each 4.7 MFD @ 250 V rating.


Those electrolytics look like the almost-soda-can-sized ones I have in a box of stuff a friend gave me, salvaged from some Sony 1" video editing machines. I think they're 4700MFD @ 220V. There's also a bunch of even bigger (physically) ones in some old linear power supplies, but they're a lot lower voltage and higher capacitance (5 digits). 

I'm watching your build with great interest, as I'm still working on bicycle-class stuff but will likely eventually graduate to bigger things (I've had a couple of people ask if I could do this stuff for their cars).
________
Paxil Lawyers


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## Russco (Dec 23, 2008)

Hmmm, looks very familiar. Beat you by about 20 odd years. Yep, same Powerex Darlington, but Powerex dropped Darlingtons several years ago. 

http://www.russcoev.com/oj_motor_controller.html


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## blackpanther-st (Apr 4, 2009)

Russco said:


> Hmmm, looks very familiar. Beat you by about 20 odd years. Yep, same Powerex Darlington, but Powerex dropped Darlingtons several years ago.
> 
> http://www.russcoev.com/oj_motor_controller.html



Interesting! how did they work for you? obviously they at least did the job from looking at your site.

I can't see the values on your caps but from the physical size and count it looks like your capacitance to modal ratio was about the same as well; though if you say you did this 20 years ago I doubt that those caps had the MFD density that the Cornell Dubiliers I am using now have.

I see you did nearly all of the electronics components for that project, were you manufacturing these, or were they just for your own project?


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## blackpanther-st (Apr 4, 2009)

Amberwolf , well the they are not quite that big, there about the size of a D cell battery, but I do remember those huge ones you are talking about. when I was in high school I had a few I scavenged from a pare of 1970's era computer printers; they were like about 5 1/2" tall and 3 1/4 in diameter and something like 23 Farad! (not micro Farad) I built a 250 watt guitar amp for my senior project using them; I know it was overkill, but I had them and had to use them.


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## Amberwolf (May 29, 2009)

blackpanther-st said:


> Amberwolf , well the they are not quite that big, there about the size of a D cell battery, but I do remember those huge ones you are talking about. when I was in high school I had a few I scavenged from a pare of 1970's era computer printers; they were like about 5 1/2" tall and 3 1/4 in diameter and something like 23 Farad! (not micro Farad) I built a 250 watt guitar amp for my senior project using them; I know it was overkill, but I had them and had to use them.


I bet it had the cleanest, most ripple-free power supply ever.  You'd know that any hum coming out of it was coming from the guitar pickups or cords!

The D-cell comparison brings the pics into a different scale for me.  

The cap I am going to test out on my homebuilt 2QD is actually bigger than the whole 2QD! The weatherproof Pactec case I have to put the main electronics in is bigger than both, but the cap (and MOSFETs) won't be inside the case due to heat, since the case is plastic. I don't have a metal box that I can easily weatherproof that is big enough for everything yet still small enough to fit on the bike where I want it. With separate MOSFETs I can put their heatsinks out in the airflow better, too, with air on both sides of the heatsinks, instead of just the outside.
________
The View Condo


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## blackpanther-st (Apr 4, 2009)

Here are a few new pics of the current progress; first is the freewheel diodes mounted to the positive buss and soldered to the copper connection strip to the M- buss and the Darlington's collector tabs.










Next shows the positive connection plate, which gets sandwiched between the freewheel diodes and the positive buss. this plate also connects to one bank of the electrolytic capacitors and all of the polymer capacitors. 










The last photo shows the layout of the assembly with the placement of one of the polymer capacitors; they will all be in a line, parallel to the two banks of electrolytic capacitors.










My motor is fully assembled and connected to the transmission now, so once I have the power section in a workable state I can begin low voltage testing with the inductive load it will see in service.

Edit; That copper plate is #16 lbs copper, about 21/1000' thick and about 4 times heaver than some of the thickest pc board copper you can get. it is thick enough to hold its own shape. I will be insulating them where necessary with plastic sheets; most likely my transparency sheets from my wax printer, since they are intended to handle the temperature of the hot transfer drum in the printer.


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## blackpanther-st (Apr 4, 2009)

*DIY motor controller, first test with inductive load*


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## Tesseract (Sep 27, 2008)

Is the scope displaying the voltage across the switch or the motor? If it's across the switch then be on the lookout for thin spikes at turn on (if it's across the motor you might not see anything, since the spikes come from stray inductance between the switch and FWD).

What's the switching frequency? IIRC, you are using fairly old Darlington modules. Depending on the vintage, those were typically rated for 1.5kHz operation. Some VFDs of that time offered a "quiet mode" - 8khz, which is the default frequency today - but required a 25% or so derating. 

Realize that Darlingtons require a proportional base drive circuit to achieve fast switching while minimizing Vce[sat]. Count on an overall beta of 100 (so a 500A controller will require 5A of base drive... and this is continuous, not impulse, current...).

The driver circuits used these days for IGBTs and MOSFETs will hard saturate a darlington which will lead to incredibly long turn-off times. This can be mitigated somewhat with a Baker Clamp, but then your driver power is going to shoot through the roof. Proportional drive really is best for Darlingtons (and, to be perfectly honest, is such a bitch to get working just right you might question whether you really got such a good deal on the Darlingtons in the first place  ).

Anyway, looking good so far, so keep it up.


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## blackpanther-st (Apr 4, 2009)

Tesseract, The scope was across the motor output, thanks for the tip, Ill be checking across the switch now that you mentioned it; it does make sense when I think about it. Ill need to isolate the power supply to get an acuret reading; it shares the same ground with the scope. ( I don't know why the diden't make the scope with a floating ground, that hase coused me a few frustrations.)

I am running about 12Khz and so far the swiching times don't seem to be a problem; Ill know more when I put the scope on it with a heaver load. I did test it today with the motor in the car at 12v, but I was in a rush and did not put the scope on it. it was too bright out anyway, Ill need to do that at night when I can see the trace. 

As far as the bace current goes, I am well aware of that, and it is definetly the bigest drawback I see with these so far.


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## Tesseract (Sep 27, 2008)

blackpanther-st said:


> ...Ill need to isolate the power supply to get an acuret reading; it shares the same ground with the scope. ( I don't know why the diden't make the scope with a floating ground, that hase coused me a few frustrations.)


They do make scopes with floating grounds: battery powered ones 

Also, depending on how much power is required you can make a cheap isolation transformer by wiring together the secondaries of two identical LV transformers with a high enough wattage rating (cheaper than buying a portable scope, anyway!)




blackpanther-st said:


> I am running about 12Khz and so far the swiching times don't seem to be a problem; Ill know more when I put the scope on it with a heaver load. ...


Yep - storage and turn-off tail times increase with increasing base current. 12khz is just way too high for this type of module. I highly encourage you to lower the switching frequency until you just start to hear the motor "sing" at low rpms. You might be surprised how low a switching frequency you can use and still not hear the motor!

Indeed, this is one of the things I found most puzzling about the existing motor controllers out there... Switching losses are more or less proportional to frequency (one component is proportional to f^2, but it doesn't really add much to overall dissipation below 20-30khz) and since with electrolytics you end up with far more capacitance than a strict dV/dt ripple calculation would predict (to get a low enough ESR) there's no penalty, and plenty of upside, from lowering Fs. If Fs was cut in half on the Zilla Z1K - from 18khz to 9khz - I bet it would be able to deliver its peak amp rating for a 40-50% longer time period and be able to manage a good bit more than 300A continuous.

Anyway, it certainly can't hurt to try.


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## blackpanther-st (Apr 4, 2009)

I tested driving the car with the DIY controller I am building for the first time today and all went well. Only 36 volt and still a lot more work to be done, but the power section performed beautifully at that voltage and the car moved along nicely.

Unfortunately the camera battery quit just as I got to the good stuff. 

(Note) in the video I mentioned the reading on the meter as I powered up the controller; I mistakenly said volts when I should have said amps.


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## blackpanther-st (Apr 4, 2009)

A little more progress to show; the power section is basically complete except for some clean up work and an enclosure with the fans, Ill be running dual 120mm's rated at 130CFM each. 

The photo below shows the current state of the controller from the end view. 

The second capacitor bank is now complete (left side) The straps on the top allow me to reach the bolts on the positive bus (below straps) in the event that I need to dissemble the unit for repair.

In the front center mounted to the heat sink with the yellow wires are what look like MOSFET's, but the are actually are high power resistors. The two small ones in TO-247 cases are rated at 15 watts each and 2ohm's these are my gate resistors as the Darlingtons require a considerable amount of current. The larger resistor in the TO-126 case is my precharge resistor; it is 100ohm and is rated at 100 watts average per second.










I also meet my goal of completing a successful road test drive to the snowmobile club and back.

This is First road test drive of the Fiero Electro and the home brew DC motor controller. The Fiero Electro is a 1984 Fiero I am converting to an electric car. 

This is just a short 1/10th mile run and back. The Fiero Electro and the home brew DC motor controller. are designed for 144 volts and up to 1000 amps, this test was run at only 36 volts to avoid exceeding the 1000 amp limit; I do not have current limiting in place yet, 

The maximum motor side amps I have drawn at 36 volts is about 400 amps.


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## MPaulHolmes (Feb 23, 2008)

Man, that is so awesome I can hardly stand it! I think it's "snappy" near 0 rpm because your throttle is proportional to pwm Duty.


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## blackpanther-st (Apr 4, 2009)

Mph said:


> I think it's "snappy" near 0 rpm because your throttle is proportional to PWM Duty.


Yes, that and my throttle pot is a little jumpy; I need to redesign
it..


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## Stunt Driver (May 14, 2009)

Great job!

I would like to put together simplest controller 400A max for my Fiero. No smart brains wanted, just pure PWM capability, something to replace my forklift+contactor setup. Will control max current myself, and wont' do any rough driving. By the way, my 48 volt system wouldn't give more than 250A on 9" motor even thru 1A contactor if car is moving at least somewhat. So don't be afraid of going to 1000A just yet

What is the total cost of your setup? Did you just use schematics from MPaulHomes?


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## blackpanther-st (Apr 4, 2009)

Stunt Driver, I just have a few minutes right now, but in short I probably have about $300-$400 in parts invested in the controller, most of that being in the capacitor bank. (thats not including the bread board)

Yes I do plan on posting a systematic soon but it may be a week before I can get the chance to do so. 

I have been following MPauls Holmes's progress but this is my design, mind you that power sections are all more or less the same when it comes to the basic circuit, but the component choices, hardware lay out and thermal design are what set them apart. 

For the control section, I will eventually be using a micro controller, the same as MPauls Holmes, but I will be writing my own program for it aside from a few possible snippets, and the circuit will also be mostly my own but may borrow a few ideas form MPauls Holmes's project.

I should add here that I have a lot of respect for what MPauls Holmes has done with his project.

If you only want 400A then you should be fine with a half size of my power section, but you most certainly should add some sort of current limiting circuit; raw PWM circuits behave very differently from contactor setups. I am only able to get away with testing without a current limiting circuit, because my voltage is so low that I can not exceed my limit even withe the motor locked dead still. I do not dare go any higher with out a current limiting circuit; you mentioned not going over 250A at 48V with your motor, but I am I am already going much higher ( up to 400A ) at only 36V. Part of that could be differences in our motors, but also PWM circuits amplify current at lower PWM percentages.

Adding in here that the control section I am currently using to test the power section and car, is a very simple analog circuit, and is probably less than $10 in parts, Ill post the schematic hopefully some time this week.


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## Stunt Driver (May 14, 2009)

Would appreciate you to share schematics, and good luck testing and setting up!
In my current financial situation it only makes sence to go for cheap controller, probably within $200, so looking for options.


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## Tesseract (Sep 27, 2008)

Stunt Driver said:


> ...
> In my current financial situation it only makes sence to go for cheap controller, probably within $200, so looking for options.


If that's all you have budgeted for a controller I hope your EV is a _golf cart_... Here's a _rebuilt_ Curtis 1207 controller that just slides under your $200 budget:

http://www.golfcarcatalog.com/catalog/index.cfm?fuseaction=product&theParentId=1435&id=4352

Bow down before its awesome power of 24V and _up to_ 300A!!!

EDIT: obviously I was being sarcastic here, but given that you have a functioning SCR-based controller that seems to satisfy you, you will NOT get better performance from a modern controller design if all you are willing to spend is $200, _even if you build it yourself from scratch!_ So, I'd keep what you already have.


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## Stunt Driver (May 14, 2009)

I just can't step over not having economical sense in money invested in improving range of my EV which is currently 3 times my daily roundtrip (have two other projects sucking money with much-much greater ROI). Besides, my forklift SCR does great so far, for $0 invested especially. I can source some parts for pennies and possibly build better controller, just need to get my head around it.

And most probably will buy Aptera once it's avialable. You can line up to buy my Fiero and upgrade it as much as you want then

EDIT: thank for for your comment in EDIT I'll try not to bug everyone to death here, and find a way to keep myself from spending money on already running car now - that one is difficult! Can you elaborate a bit on SCR vs PWM controller differences in adjacent topic?


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## blackpanther-st (Apr 4, 2009)

My simple analog PWM circuit for testing the power section. 

This is a raw voltage controlled PWM circuit with no current limiting; current limiting would need to be added for practical use.

The first 555 is a sawtooth modulator operating at about 12KHz and the second 555 compares the throttle output 0-5V to the sawtooth output of the first 555 and outputting a 12KHz pulse stream with it's duty cycle modulated by the throttle output voltage of 0-5V; a hall effect throttle could also be used to replace the throttle pot shown.

The general NPN transistor at the end inverts the output so that the circuit shuts down with the output in an off state. If operating at higher voltages, an optoisolator could achieve the same results while adding isolation protection. 











Pin out of the 555










Ill draw out the power section soon.


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## blackpanther-st (Apr 4, 2009)

The power section.

The 39 ohm resistors are non inductive 1 watt ceramic composition, part #OX390KE. 

The 2 ohm resistors are non inductive 15 watt heat sink mounted in TO-126 cases, part #MP915-2-1%.

Technically an ancillary component and not shown is a precharge resistor, part#MP9100-100-1% which is a 100 watt, heat sink mounted in a TO-247 case.


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## mrbigh (Dec 31, 2008)

Wherever hapened with your controller?


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