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  #31  
Old 06-04-2012, 06:46 PM
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Default Re: Extended Chevrolet Express van converted

The SJ700 looks pretty good just from what the one line in the PDF says

"advance trip avoidance functions"

And the surge voltage supression

Plus it claims the sensorless vector can produce peak torque a .3 Hz. Might be work a look, though they are probably pretty expensive. Eventually though, they will show up used at the surplus stores. I'll keep an eye out for one.

If you are keeping the transmission in your car(s) a drive with torque mode would be really useful I'd think. It could make the car behave essentially as if it still had the gas engine, just no gas. If you could then get a drive with torque mode and speed mode switchable with a small switch in the car, you could use them to switch between "race" and "street" modes. The speed mode would be good in the snow, since you always set the speed and not the torque, therefore you have control of the wheel speed and not the torque. The torque mode would be good for racing or fast acceleration, since you want it to hit maximum speed as fast as possible. Good in the corners too, you don't want Regenerative Braking on pedal lift when you are taking the corners fast.
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  #32  
Old 06-06-2012, 04:32 PM
JRoque JRoque is offline
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Default Re: Extended Chevrolet Express van converted

Hi. I bought my 5HP SJ300 new on eBay for $300. There's a 1 HP version now, used, for ~$120. Too bad the encoder board is more than the drive itself, but it is also available on eBay.

I fought myself over what to do with the interface. On the one hand, you do get more flexibility by intercepting the pedal signals and massaging before sending to the drive. On the other hand, it might be more reliable to connect the pedals directly to the drive and use the micro to command max current and voltage levels. If the micro were to fail, the drive would still work. It would also reduce the chance of sudden max throttle or brakes if something were to go wrong with the micro. But I also have a counter argument for that so you can see I've gone nowhere with this.

I did build a prototype to link the pedals to the drive and it worked well with the exception of proportional brake regen as mentioned above - the drive shuts down when you command 'stop' so it loses track of the motor speed. This will probably be cured by adding the encoder.

The SJ300, and I imagine many more also, can resume motor speed realtime without the need to stop the motor like some old drives did. Hitachi also provides free software for their drives. I did try ProDrive package but never got it to talk to the VFD. IIRC, it had something to do with the drive port I was using and not the RS485 i/f. Allen Bradley, Siemens, ABB and Eurotherm come to mind as good drives also.

JR
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  #33  
Old 06-07-2012, 01:57 PM
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Default Re: Extended Chevrolet Express van converted

Sad news today



While range testing the Express, the controller exploded.

I suspect it was due to overvoltage.

I was going down a hill, I had my foot on the brake pedal. At the bottom I let off the brake pedal and the controller exploded.

To be honest, it needed a better controller anyway. The new controller I want to make will have better IGBTs, it will be liquid cooled and it won't be in the passenger compartment (the explosion was quite violent, I won't have anything like that sitting next to me again) and I want it to have FOC/Vector control

Stay tuned for the next controller and an overhaul of the van
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  #34  
Old 06-07-2012, 06:12 PM
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Default Re: Extended Chevrolet Express van converted

that is terrible news. all 3 phases are gone? at least, the motor did not "run away" ( ac motor advantage.) any new ideas/ plans for the next controller?
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  #35  
Old 06-07-2012, 06:45 PM
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Default Re: Extended Chevrolet Express van converted

With the new controller, I will use 300 amp 1200 volt IGBTs (or maybe 600 amp 1200 volt), I will also use larger gate resistors to slow the switching to reduce voltage buildup. I'll keep the same switching frequency ( 3 kHz) and they will be liquid cooled

I'm also going to use a dynamic braking resistor to work in all braking situations, that way the voltage won't buildup and go out of control.

My theory is, the capacitors I used are 350 volts each, so in series that means 700 volts max. When I had my foot on the brake pedal the voltage was 720 volts, usually it goes alot higher though. I suspect when I let off it jumped too high for the capacitors to take.

Which brings me to my next change, I will use the highest voltage capacitors I can get, which are hopefully 450 volts or more. In series I want 900 volts DC, higher than the cut off point of most 500 volt VFDs. (830 volts)

Also most VFDs it seems activate the brake chopper at 730 volts, so again, probably too much voltage caused my problems.

The induction motor was definietly a good choice, especially since I had to get it towed with the rear wheels on the ground, meaning the motor had to be turning. Not a problem for the induction motor.

Last edited by subcooledheatpump; 06-07-2012 at 06:53 PM.
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  #36  
Old 06-10-2012, 09:49 PM
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Default Re: Extended Chevrolet Express van converted



These are the replacement IGBTs, they are CM300DY-24H

Up next, liquid cooled heatsink/coldplate and 450 volt 6000 microfarad capacitors
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  #37  
Old 06-13-2012, 05:13 PM
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Default Re: Extended Chevrolet Express van converted


IGBTs are mounted on the liquid cooled heatsink
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  #38  
Old 06-27-2012, 02:25 PM
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Default Re: Extended Chevrolet Express van converted



I got the new controller (temporarily) in today.

I tested it, and it works. Some programming to work out, but it works.

In the upper left of the picture is the water cooling pump. I decided to keep the controller inside the van, and move the batteries out. The controller is now where the accessory batteries used to be. The accessory batteries will be moved to where the engine used to be.
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  #39  
Old 06-29-2012, 06:37 AM
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Default Re: Extended Chevrolet Express van converted

now thats one fiiine water cooled heatsink!!!
where/how did you get it done? because i want one..
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  #40  
Old 06-29-2012, 08:14 AM
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Default Re: Extended Chevrolet Express van converted

The surplus store that I get my power electronics from has them for sale.

Sadly though, they don't have them up on ebay, you actually have to go in person to get one.

I knew where they were for a while and one day I decided to get one. Even some of the employees were impressed with it, they didn't know it was there...
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