Controlling a big sepex
 

I am rebuilding an old SCT electric Rabbit. It has a shunt/sepex motor in it and a 108 volt battery. Currently, it has a controller on the field but not on the armature. It runs by idling the motor at full field; you let out the clutch to start and weaken the field to speed up. I want to install a controller on the armature, so I can raise the voltage to the motor's rated 144 and get better performance on hills. Will the open source controller work for that? I understand that, without the series field, there is not enough inductance for some controllers to work well. Would that be an issue here? Another question is regen. The car has it, and I want to keep it. Will it work to simply put a big diode across the controller to carry the regen current to the battery, or is it more complicated?

thanks,

Steve Gaarder

The syncronous rectification controller I think can be modified pretty easily to power a sepex motor. But if you already have a controller for the field, then I don't see why it would be a problem for the standard controller controlling the armature. With smaller inductance, it would mean current changes faster, which would mean possibly changing the P and I constants for the PI loop. I think jackbauer is running a sepex motor with the open source control board, and a custom IGBT controller. It's 11" diameter too.

Which controller are you referring to? While I do have a controller for the field, I expect that there are significant pluses to having one controller do the whole job.

thanks,

Steve Gaarder

Oh, I finished a control board for a synchronous rectification controller, which can be modified (by changing software only) to control 2 separate coils.

hey paul whats the odds on my getting hold of one of those boards? :)

Hi Jack! I'll definitely send you one. I just need to order them. Here's the sequence of events that probably need to happen:

Somehow get $1000 for Eagle.
Send in the board to China (pcb cart is CHEAP!)
That's it...

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Instead, I will probably do the following:
Send the board to that one super expensive place. Get like 3 of those friggen things for like $300 and feel real sad inside.
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Option 3 is to send it to that one company that's quite a bit cheaper, but I need to get screen shots of it I think. I just need to do that. The bms and charger are ready for testing, so I'll do that first I guess. IT won't be long now for the control board.

Hey Paul,

I have a copy of Eagle Pro V5.9.0 that I can send out to you next week.

Let me know if you want it. :thumbup:

- Mark

Ithaca, NY = ~1 hr drive from me. Cool.

Is this "Rabbit" a VW car?

Yes, It was converted when new in 1982 or thereabouts by South Coast Technologies.

Let me see if I have this right: a synchronous rectification controller uses MOSFETs instead of the commutating diodes, and so the controller board has a second output to control those MOSFETs. What I could do is use this controller board with two diode-based power boards, one for the armature and one for the field, and rework the software to handle this. Is this correct?

thanks,

Steve Gaarder