# P&S Controller-MRBIGG Driver-6 IGBTs= Powerful Home-built controller



## Jimdear2 (Oct 12, 2008)

Many of you will recognize us because we are electric garden tractor pullers.

Two years ago we converted a couple of old Cub Cadet tractors to battery power and had a TON of fun. We competed with ICE tractors with modified engines and did WELL.

Last year we started on a project tractor that would be the garden tractor equivalent of the 7000 pound 2000 plus cubic inch aircraft engine powered big tractors.

That would be the 1350 pound ultralight class, these tractors are powered by 1000 to 1500 cc motorcycle engines with a weight, with driver, of 1350 pounds.

We started with a 13 inch GE Hi Lo traction motor, a custom frame, a car differential, a P&S controller that we modified to push 650 amps and a 165 volt 24ah Headway 3P/50S battery.

After a year of development, among other things, we determined we need a lot more controller. Referring to the side view picture. The battery will move as far forward as possible. Ditto the breaker/disconnect and the controller moves from above the motor to just behind the battery and many former components are now aluminium.

So the electrical guy on our team came up with the following

A P&S controller card;
A high range current sensor;
Six 600 volt 400 amp IGBTs;
A IGBT driver card designed by MRBIGG;
Two TYCO contactors;
A 10x16 inch piece of Finned Heat Sink;
A set of good capacitors;
A lot of 3/8 thick copper buss bar;
A nine inch fan mounted below the heat sink to keep things cool (we have a water cooling plan but we are trying to keep things simple).

Also a new 4P/50S 104 kW quick burst potential Headway battery (a 130 volt 800 amp for 20 second potential).

We wanted a controller with a lot of future potential so we are going to de-rate it from a full bore 2400 amp 600 volt (I know pretty unrealistic) to 1000 motor amps to start.

I'll attach a couple of pictures of the set up, bread boarded and running the 13 inch motor on a single IGBT.

Since the pictures we have mounted the controller boards, We found during testing we need a bigger DC to DC for the P&S board and ordered it. Got final specs on the needed resistors and diodes for the IGBT controller circuits. I also cut and formed a nice aluminium enclosure.


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## Woodsmith (Jun 5, 2008)

*WOW!*

I can't wait to see it in action. I reckon I have some catchin' up to do!


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## Jimdear2 (Oct 12, 2008)

Woody,

Thanks for the comment.

We are just hoping that it ain't all magic smoke when we really get a load on it.

We are just combining tried and proven open source components other people have put a lot of work into, hoping for the best.

Wish we could do it the right way like the crowd over at EVnetics.

Jim


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## SandRailEV (May 11, 2012)

So, where is the best place to buy IGBTs?


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## Jimdear2 (Oct 12, 2008)

SandRailEV,

We got ours from eBay. To find them at a reduced price mostly you will find end of run leftovers or obsolete units on eBay. There are also some used items.

Other places would be electronics supply houses but you will pay full price there.

Best to have some knowledge or a knowledgeable person help with the purchase.

I'm interested in your handle, SandRailEV does this indicate an interest in sand drags? We plan on fitting some paddles and trying out the tractor later this year.

Jim


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## DIYguy (Sep 18, 2008)

Jimdear2 said:


> Many of you will recognize us because we are electric garden tractor pullers.
> 
> Two years ago we converted a couple of old Cub Cadet tractors to battery power and had a TON of fun. We competed with ICE tractors with modified engines and did WELL.
> 
> ...


Looks GREAT Jim! This is DIY at its best. Can't wait to see how these mods work out.


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## SandRailEV (May 11, 2012)

Jimdear2 said:


> SandRailEV,
> 
> We got ours from eBay. To find them at a reduced price mostly you will find end of run leftovers or obsolete units on eBay. There are also some used items.
> 
> ...


 
Hi Jim,

I bought this sandrail several years ago and it ended up being a humble piece of crap.  I had all the intentions of rebuilding it with the original ice but recently became interested in EV conversion. Here's what it looked like when I bought it.










And here is how it looks now...











I have no interest in off-road with it. It's going to be my test-bed for EV conversion. I am still researching 3-phase drives & motors and have some ideas I am looking into. I am interested in assembling a drive with external IGBTs but it seems like it's a lot cheaper to just buy a complete manufactured drive complete than to "hack" one together. Maybe I'm missing something here.... 

I do like the completeness of the Curtis 1238 with the AC-50 motor except that it's seriously limited on pack voltage. I would like to run a V/F of about 1.6 such that the motor sees 100 volts at 60 cycles and continues up to about 150 volts at 90 cycles. This would help to keep torque from dropping off at RPMs above 3600. The Curtis controller only allows pack voltages up to about 130.

Since my direct experience with VFDs is a little limited, I need to go slow and cheap until I have the skills and also know where to get the larger parts at the right price. I am skilled with 3-phase motors though and do quite a bit with electronics in general, so I just need to gain some hands on experience with VFDs. Once there, I can probably hack something together... Thanks for any help you can provide.. 

Anyway, nice job you have going on there... Keep up the good work....

Sorry, didn't mean to hyjack your thread...

Tom


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## jackbauer (Jan 12, 2008)

Nice work Jim! What caps are you using? One thing I did on my controller was to run the battery and motor terminals on opposite ends of the bus bars if that makes sense? Not sure it makes a difference but it should , in theory anyway, allow the devices to share the load more evenly. I also used a vicor 15v 100w dc dc which is major overkill but they were on ebay a year or so back for under $10. You want a really strong voltage source for driving that many igbts. Remember to use resistors of typically 10% of the gate resistance on the kelvin emitters. Those big bus bars will help with heat dissipation but I'd be a bit concerned about using air cooling. That's all I can think of for now


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## Jimdear2 (Oct 12, 2008)

Damian,

Great to hear from you. You were one of the inspirations behind this controller.

I'm afraid that I'm electronically challenged, Darin, whom I believe you have corresponded with, is the electronics guy. I can only say (what he told me) that the caps are 600 volt and are of the film type. I'll answer what I can and refer the rest to Darin.

The layout of the buss bars was/is constrained by the installed location. Big controller with six IGBTs and a small space. <edit> I do remember Darin saying that the way we have the internal connections done it would "balance the load" <end edit>

We also needed to go with a MUCH larger DC to DC to power the IGBT drivers on MRBIGG's board. W also had to power the DC to DC from a source before the resistor. I believe that Darin said you deleted that resistor from your controller, he left it in for "safety".

Right now Darin is running only one IGBT to a 150 amp load trying to establish the correct gate resistor (this will mean more to you than me) and other esoteric stuff.

I'll see if I can't get Darin to also answer.

Be well and keep inventing/developing,
Jim


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## Jimdear2 (Oct 12, 2008)

SandRailEV said:


> Hi Jim,
> <snip> Here's what it looked like when I bought it.
> 
> 
> ...


Funny ours looked similar last year

and similar this year (we did start assembly and have the front end and steering back in)



SandRailEV said:


> Anyway, nice job you have going on there... Keep up the good work....
> 
> Sorry, didn't mean to hyjack your thread...
> 
> Tom


No hijack, all information is useful.

Jim


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## badfishracing (Dec 4, 2009)

Jack,

The caps are some older Electronic Concepts Film capacitors. 100uf each, around 100A ripple best I can tell. X5.
The Battery (-) goes opposite the motor (-). I was thinking the battery (+) didn't make any difference, but I supposed it still would. That could be revisited.
Had a 15W Dc-Dc, but that wasn't even enough to charge up the first Cap on the IGBT driver. Went with a 40W and that seems to have done the trick.
Not sure what you mean on the Kelvin Emitter resistors? We've got gate resistors 3 Ohm for turn on, and 8.2 ohm for turn off. But haven't put a scope to it yet. Not using the collector shorted sense thing.



Darin





jackbauer said:


> Nice work Jim! What caps are you using? One thing I did on my controller was to run the battery and motor terminals on opposite ends of the bus bars if that makes sense? Not sure it makes a difference but it should , in theory anyway, allow the devices to share the load more evenly. I also used a vicor 15v 100w dc dc which is major overkill but they were on ebay a year or so back for under $10. You want a really strong voltage source for driving that many igbts. Remember to use resistors of typically 10% of the gate resistance on the kelvin emitters. Those big bus bars will help with heat dissipation but I'd be a bit concerned about using air cooling. That's all I can think of for now


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## jackbauer (Jan 12, 2008)

The kelvin emitter is the small emitter connection beside the gate connection. Ideally you want about 0.3R between each kelvin emitter and the driver.


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## Jimdear2 (Oct 12, 2008)

jackbauer; said:


> Those big bus bars will help with heat dissipation but I'd be a bit concerned about using air cooling. That's all I can think of for now


Damian,

A little more detail on the cooling set up. Remember this thing will be under full power for only 20 to 30 seconds. Thanks for your concern though, I always listen to what you have to say.

For now we have everything mounted to a 10x16x2 inch finned heat sink. The plate is 3/8 inch or so thick with the remaining height being fins spaced about 1/4 inch apart. Directly attached to the bottom (fin side) is a 9 inch radiator cooling fan moving air through the fins. I also plan a 120 mm fan mounted in one end cover to move air around those copper bars and components not attached to the heat sink plate.

If that should prove inadequate I will insert 1/4 inch copper tubing in between every third or fourth fins and pot them in using a suitable heat transfer material. To keep the fluid circuit that is in contact with the heat sink short I will manifold it and use 3 or 4 circuits. I have a number of M/C radiators and overflow tanks to do the circuit

What do you think?

Jim


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## jackbauer (Jan 12, 2008)

I think that will be fine Jim. You have more than enough thermal mass there to take the heat pulses for such short runs.


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## Salty9 (Jul 13, 2009)

Jim,

Have you checked post #97 in this thread? Looks like a possible source for reasonably priced IGBTs and other goodies. 

http://www.diyelectriccar.com/forums/showthread.php/open-source-ac-vfd-conversion-72000p10.html

Chuck


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## Jimdear2 (Oct 12, 2008)

Well, we got back at the controller build up after replacing an IGBT driver board and cap. It appeared that we has a minor bit of magic smoke release during the initial testing, a resistor on a temp breadboard touched. Darin replaced the board and cap so we are getting back to the controller buildup.

For the final assembly we started off by assembling all of the IGBTs to the heat sink. then the front cover with insulators, buss bars and the caps. From there we finalized the mounting of all of the electronic bits. 

With all of the stuff installed into the controller we (Darin) did a hook up using the motor fields and three big (bus/train???) breaking resistors. Once we get everything sorted we will hook up the traction battery to the controller and put a load on the controller.

Darin hooked up a scope and found that we still had a problem from one of the IGBT driver boards. Today he traced it back to a damaged trace on the IGBT controller board. After a bit of repair he managed to get things smoothed out.

The following pictures show the controller sequence as we assembled it. Not shown, but installed, is the 4 inch fan installed into the rear cover and the 9 inch fan installed onto the bottom of the fins of the heat sink. The 4 inch fan is hooked in parallel with the precharge system, fan comes on when the precharge is done. The 9 inch will come on when the throttle is applied.

Maybe tomorrow will be the big day. I am electronically challenged so I loet Darin make al of the decisions there. I'm working on all of those last minute fussy little things.

More as we succeed,
Jim


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## Jimdear2 (Oct 12, 2008)

Well today was the big day. We powered up the complete controller with full traction battery power

YIP YIP YIP YIPEE . . . NO SMOKE

Darin got all the minor problems in the controller fixed yesterday. So today, as usual just when we are ready to go we find that the scope is not working, so now he has to fix the scope. We finally got to put some current through all six IGBTs after an hour or so of puttering with the scope.

Started off for the first try with 24 volts and pushed about 300 amps (almost blew a battery).

Darin says the scope trace shows the on off pattern as pretty clean, although he says he may want to try some snubbers (you'll have to ask him what that is) because there was a ??rebound spike???. As I say, I'm electronically challenged.

After we tortured a couple of 12 volt Odyssey's down to 3 volts we switched over to the 165 volt Headway traction battery. Darin set the controller to push some real current. With the limits Darin set into the controller (I may have these numbers a bit mixed up) I think we got right around 1200 motor amps and around 75 motor volts and were pleased to find that the battery only sagged to around 140 volts.

If we get the 2000 motor rpms we are hoping for with this motor voltage, that will give us around 115 peak horsepower and produce some 300 foot pounds of torque at the motor shaft. With a 3 to 1 chain and a 5.14 to 1 diff reduction that's around 2400 foot pounds of torque at the wheels at zero rpm.

The above doesn't really mean anything real (except a lot of broken chains) but it's a lot of fun to speculate.

I forgot my camera today  so no pictures. I'll be going back Wednesday and I'll see what I can photograph.

Jim


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## Woodsmith (Jun 5, 2008)

That is coming along really well, Jim, Darin, really well done.

I do sometimes envy those who can see how the magic smoke works in the little black boxes.

Jim, as an aside, you have a 15.42:1 reduction ratio motor to wheel. How tall are your wheels?
Just trying to guestimate how it compares with my transmission ratios with my 28" and 31" tall tyres.
Cheers.


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## Jimdear2 (Oct 12, 2008)

Woodsmith said:


> That is coming along really well, Jim, Darin, really well done.


Thanks for the encouraging words. I've got to admit that I wasn't as confident as Darin was about the final result, but he is the electron pusher and "knows".



Woodsmith said:


> I do sometimes envy those who can see how the magic smoke works in the little black boxes.


That's me as well, I'm pretty much at the level of, duh, the red wire goes here doesn't it?



Woodsmith said:


> Jim, as an aside, you have a 15.42:1 reduction ratio motor to wheel. How tall are your wheels?
> Just trying to guestimate how it compares with my transmission ratios with my 28" and 31" tall tyres.
> Cheers.


Woody, thanks for the nice, polite. correction of my fubar of the total gear reduction. That's the kind of mistake you make when you are old and tired.

I've built myself an excel wheel speed calculator, I would send you a copy but I haven't figured out how to attach an excel file. I can email it if you like.

Jim


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## Woodsmith (Jun 5, 2008)

Jimdear2 said:


> Woody, thanks for the nice, polite. correction of my fubar of the total gear reduction. That's the kind of mistake you make when you are old and tired.
> 
> I've built myself an excel wheel speed calculator, I would send you a copy but I haven't figured out how to attach an excel file. I can email it if you like.
> 
> Jim


Not really a correction as the info is there anyway.

I have been working on 11.28:1 in high range and 20.069:1 in low range to get what I think might be a reasonable spread of road speed with the 31" tyres.

I have made up a calculator for gear ratios, and road speed per 1000rpm for any given tyre diameter. Just wondering if we are in the same ball park.
I get 8.2mph per 1000rpm in high and 4.6mph per 1000rpm in low if I use the Lada Tbox and Salisbury axle.


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