Paul & Sabrina's cheap DIY 144v motor controller

[Dwffy]

Thanks, Jack

[wakinyantanka]

Originally Posted by jackbauer

It can handle 30 amps. At 12v! You'd need to use a kilovac or other ev rated hvdc contactor.

Hi Jack,
I'm asking you because you seem to have success with igbts, but anyone with knowledge please feel free to elaborate.
I found some high power igbts, not cheap but I think I can afford them, anyways it's got me rethinking my design. They claim to have internal freewheel diodes, does this mean that these can be installed without external freewheel diodes? If so, will the control board that Paul has drive them without issue?
If not, please explain why.
Thanks

[Weisheimer]

Originally Posted by snakub

Yes I have almost exactly what blackpantherst does. ....I am using an 8 amp hour twelve volt battery and a battery charger powered off of the traction pack to power B not Bx which would take a lot more drive current I measured the current going to B and it is only about 2 amps so all in all my power section took 8 amps.

The battery is being called upon to deliver 8 amps now, though I think it might work for a test,
You are looking at 96 watts of drive already and you haven't even kicked it in the butt yet!
I'd be looking to up the size soon.
I'd add a .1uf 50v ceramic cap from the collector of the driver MOSFET to common too.
I'd also keep a close eye on that battery while testing too.
You may have more blown module issues if it starts going flat.

Are your BX lines tied together as in BlackPanthers schematic?

Originally Posted by snakub

But can I put the fuse in as one of the series connection to my batteries or would it be better to have it connect to the positive going out?

You can put the fuse anywhere in series with the battery loop.

I have a fuse at the most positive battery, a circuit breaker at mid pack
(because it is convenient and in between the seats for easy reach)
and another fuse in the negative lead of the pack.
You'd be fine with one fuse at any point in the loop.
Just put it in a convenient spot to check and replace if needed.

Originally Posted by snakub

I wasn't really talking about if the mosfet shorted I was just trying to say that if I have the current sensor hooked up to motor negative wouldn't that still limit my current by resetting the PWM at appropriate times by turning off the mosfet? What did tesseract mean by hard saturate?

The control board is only going to be able to limit current when it has proper control of the modules.
I'm not so sure that you're there yet.

And this is important to understand:
NO CONTROL BOARD can limit the current through an Emitter-Collector short in a module.

That is part of what the fuse is for.
It is also why I am fond of multiple disconnects.
You won't plow yourself into a tree if you can get the power turned off after that kind of a failure!

Take a look at:

Baker clamp - Wikipedia, the free encyclopedia

It speaks to the issue of saturation and turn-off.
A couple of high speed diodes are used in a baker clamp
and would keep the module from reaching saturation
which will help with the turn-off time.


I'll see if I have a spare rev C board that is populated enough
to compare with your measurements. I know mine is missing
the DC-DC converter, but I think it is mainly intact otherwise...
It will be tonight before I do that.
I've got to move along to log splitting for now!

[jyanof]

Originally Posted by Dwffy

I open the 12v bosch relay which I used to switch the heater on and off because it says it can handle 30 amps. The contacts were welded together so I now conclude that there must be a way that I can turn my heater on and off without burning up relays, but I am at my wits end.

as Jack said, you'll have to find a relay rated for your voltage. But, just to reiterate, make sure you find something that is DC rated. A 120V AC rated relay will not be able to break 120 VDC (I think it's only like 38VDC, some of the AC relays will also have a lower DC rating).

I had purchased a 150VDC 20A relay from one of the EV suppliers... shoot, i can't figure out where I got it, but it was about $20.

[jackbauer]

wakinyantanka can you post the part number?

[jyanof]

Originally Posted by jyanof

I had purchased a 150VDC 20A relay from one of the EV suppliers... shoot, i can't figure out where I got it, but it was about $20.

oops, I was off a little. It's a 10A relay, and it was $30.

EV Source - Relays

[jackbauer]

the new build continues. Hope to do final testing and assembly this evening. Note the two resistors and schottky diode used on the igbt drive and the shorted gate to emitter pins on the high side for use as freewheel diode.

[jackbauer]

Done! I'll test it on the motorcycle tomorrow before dispatching to my friend on monday.

[Weisheimer]

Originally Posted by jackbauer

the new build continues...Note the two resistors and schottky diode used on the igbt drive and the shorted gate to emitter pins on the high side for use as freewheel diode.

Jack,

Nice job as always!

Could you do the kindness of posting the values of the resistors and diode.
I think that you did that earlier in the thread, but this is a pretty complete
picture of using the Revolt with a different power section.

Also, remind us of the part number of the IGBT module.
Is this pair "matched" for Vce from a case lot?
IE, it isn't two random modules put together.
I can see that you have used a number of poly caps here as well, and
that is a good thing!

Anyone contemplating this type of build will be well guided by this fine example.

Thank You for sharing!

Mark

[jackbauer]

Resistors are 10R 0.25w carbon. Diodes are Vishay SB160-E3/54 but any standard 1A schottky would do. The igbts are Powerex CM400DU-12F. These are 400A 600V. They are matched pair from a group buy organised by Adam. Poly caps are 1uf 250v.

a useful modification would be upgrading the dc dc to one with a 15v output. This would be more suited to igbt drive. A Traco TEN 5-1213 is a drop in replacement.