# InPower/Chennic Sepex Controller - Photos



## Tesseract (Sep 27, 2008)

green caveman said:


> ...
> 1) At random times, but fairly frequently, the field current spikes and the armature current reverses. The field current runs along at ~20-35A, will spike to 75A+ and the armature then gives a current reading of -400A or so - big regen. In the car, the effect is that of stomping on the brake for 1/2sec or so.
> ....


These kind of problems are almost certainly the result of noise from the power stage switching affecting the control circuit. Nothing short of a total redesign fixes this.


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## green caveman (Oct 2, 2009)

Tesseract said:


> These kind of problems are almost certainly the result of noise from the power stage switching affecting the control circuit. Nothing short of a total redesign fixes this.


Would running a controller at a voltage higher than design cause/exacerbate that?


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## Tesseract (Sep 27, 2008)

green caveman said:


> Would running a controller at a voltage higher than design cause/exacerbate that?


Sure.Noise can be from too high of a dV/dt (change in voltage over time) or too high of a dI/dt (change in current over time).

For example, the Shiva prototype worked fine at 345V but occasionally glitched at 455V. I had to move some traces and add some more filtering to a couple of signal lines on the adapter board to fix the problem. Easily done, but it required a redesign. It also required *looking* for such problems in the first place.


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## green caveman (Oct 2, 2009)

Can I use a different control board with the power board from this controller? Is there any hope that this would work (not "will it work", just is there a hope in heck)?

I'm thinking the control board from the Open ReVolt.

1) Pull the control board (not trivial - epoxy to remove). Now I have a power board with 24 (presumably) MOSFETs. It looks as though 20 are armature and 4 field.

2) Build the ReVolt control board. Attach to the 20 armature gates on the power board.

Would I now have the possibility of having a 105V series motor controller? 

Some things bother me. First, the capacitors are 220uF on each MOSFET - much lower than the ReVolt. The ReVolt also has a diode paired with each MOSFET - I don't see any evidence of these. There are three polypropylene capacitors on the ReVolt.

Assuming the answer to this point is, that might work, then we can take the next step.

If I recreate the PWM circuit from the ReVolt (everything attached to pin 15 & 16 of the ATMEGA, except the undervoltage which could be pulled across) and assuming there are two spare pins on the chip (I think so, but I need to dig deeper), I have a new and different PWM circuit I can use to control the field. I can gate the remaining 4 MOSFETs. I think the software for that is managable, although I'd need to understand how to control regen to get it right.

So, any chance?

If it might work I'm probably willing to give it a try. If I fail, I haven't lost much, buy a Kelly and move on. 

If I succeed, then I have a working Sepex Controller, but much more than that, it would be easy (I think - remember I know nothing about electronics) to modify the power board of the ReVolt, so one of the MOSFETs controls the field and you have 9 controlling the armature - a 450A/50A field Sepex controller.


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## major (Apr 4, 2008)

green caveman said:


> .........The ReVolt also has a diode paired with each MOSFET - I don't see any evidence of these...........


Hi green,

The Chennic controller would have used mosfets instead of diodes such that it had a half bridge armature controller capable of regeneration for the SepEx application. And the field control would have been an H-bridge having no diodes.

I don't know much about the ReVolt, but if it used freewheeling diodes it is the standard quarter bridge or chopper circuit and as such the control may not be suitable to half bridge topology.

I don't know much about the Chennic company. Are they so bad as not to help you? At least Kelly attempts to help after selling you a bad product. 

Regards,

major


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## green caveman (Oct 2, 2009)

major said:


> The Chennic controller would have used mosfets instead of diodes such that it had a half bridge armature controller capable of regeneration for the SepEx application. And the field control would have been an H-bridge having no diodes.


OK, so let me see if I understand even if only at a very basic level. 

In principle:

I could control half of the armature H-Bridge with a PWM signal and have a series motor controller.

I could control half of the field bridge (PWM) along with the armature and have a Sepex controller with no regen.

Am I then correct in saying that to get regen I would switch the field bridge and continue to control the field with PWM and open the "other" half of the armature bridge and get reverse current flow into the batteries?



major said:


> I don't know much about the ReVolt, but if it used freewheeling diodes it is the standard quarter bridge or chopper circuit and as such the control may not be suitable to half bridge topology.


Almost certainly more than I do. Sounds as though it's not as simple as I first postulated I'm willing to copy/paste a small circuit (with the understanding that may or may not work), but more than that it's out of my area of expertise.



major said:


> I don't know much about the Chennic company. Are they so bad as not to help you?


So far no word from them, so I would say the short answer appears to be yes. They didn't make the product (I'm not sure that they manufacture anything). I *suspect* that this is a perfectly good 72V Sepex controller (manufactured by InPower), but it had a 120V sticker on it when they sold it to me and the field amps are low even though they knew the motor specs. The conversion has taken a while and so the controller has been on the shelf for more than a year, but that really doesn't seem likely to be the issue here. I'd be happy to hear their side of the story, but, as I say nothing yet.



major said:


> At least Kelly attempts to help after selling you a bad product.


I think that Kelly has been making an effort on product quality recently. Most of the recent failures reported seem to be user error, admittedly that user error was foreseeable and might have been avoidable with better design (pre-charge), but the reports of "just smoked while driving" seem to have decreased or still refer to older controllers.

I'm sure my sample (primarily reports to this forum) is smaller than yours, so maybe it's more optimism since the choice for 100V sepex seems to be Kelly (the HSE controller for 50A field) or Elektrosistem.

Elektrosistem seems fine, although I'm concerned about their regen control. It's also a little irritating that I have to pay $400+ for an 80's style proprietary programming pendant especially as the controller seems to have a standard RS422 serial interface. If that's correct, they could easily have a PC interface even without changing the controller software.


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## major (Apr 4, 2008)

green caveman said:


> I could control half of the armature H-Bridge with a PWM signal and have a series motor controller.


In the typical SepEx controller, the armature is connected to a half bridge. You must modulate both the upper and lower switches.



> I could control half of the field bridge (PWM) along with the armature and have a Sepex controller with no regen.


I guess or have regen. You don't reverse field current to regenerate.



> Am I then correct in saying that to get regen I would switch the field bridge and continue to control the field with PWM and open the "other" half of the armature bridge and get reverse current flow into the batteries?


Not quite. The control has some complexities. I can't begin to teach you how to do it  That's not to say you shouldn't play around with it.


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## green caveman (Oct 2, 2009)

major said:


> I can't begin to teach you how to do it


Wise choice, I'm not even sure that I'm ready for the training courses, let alone an attempt to educate!



major said:


> The control has some complexities.


Ah! This is a phrase that should be memorized since I feel it could well be useful to quote it over the smoking remains of a large pile of electronic.


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