Improve power stage design, use planar DC bus, put closer modules, ddd snubbers and it shuld live much longer 
DS conclusion is correct, and this is not a regenerative braking. After turning on lower transistors, the current circulates through the motor and transistors, dissipating power in their resistances. Fortunately, most controllers allow external PWM control (as a last resort, you can apply APWM directly to brake input pin), and this should allow regeneration: when transistors are on, circulating current rises and stores energy in motor phases leakage inductances, then after switching off, that energy discharges through aniparallel diodes to DC bus.One thing I was never able to verify is if the chip is capable of offering an effective regenerative braking. I think the three adjustments were for the acceleration, deceleration, and peak current limit. In theory the deceleration constant could affect regen, but the datasheet also mentioned the chip was designed to "coast" the motor if rotor speed exceeded the commanded speed, and the actual brake switch could be dangerous since it's basically uncontrolled and amounts to shorting out the motor.
This is perfectly normal for speeds beyond base speed. BEMF has exceded DC bus voltage and regenerative current has flowed through antiparallel diodes even in the case the transistors have been completely switched off.What's strange is I did observe a fairly powerful electric braking effect when the motor was spun above the normal operating range from driving downhill in a low gear.
It was a real regenerative current. Uncontrolled, so it might be dangerous for your controller.Although again, I had no way to know if power was really going back into the battery in that instance. I guess I'll never knowIt felt like hitting a speed governor.
David,...I've seen that line of powerex IPMs and they are very nice. Integrating the gate drive into the IGBT sounds like a great way to simplify everything and improve reliability. Not to mention space savings. 300 amps is a bit low for what I need (currently have 400amp modules) but $400 is a decent price for what it is. Its already getting close to what I would spend on external gate drivers that would be needed for rebuilding my existing setup.....
Hmm........David,
There are other choices for amperage. The sister module is 450 amps and runs about US$700 as I recall.
I was already thinking to do that since I can easily make an aluminum liquid cooling setup in our shop.You would probably want to consider using liquid cooling with a chill plate, pump, and radiator regardless of which module you used.
You are very likely correct. The car struggled to reach 65 MPH and I highly doubt it really needs 50Hp to sustain that speed. I wonder if I was getting around on as little as 20 kw of power? Eventually I should be able to do some comparisons once its running again and I have working meters. Its one of a few questions that kept me up at night.You do have 400 amp rated modules in your existing controller.
Do you REALLY get anywhere near that current through them though?
I suspect not.
How do I know if it gets over amped? It never overheated, but I realize thats not much to go on.And you do have a BLDC motor with magnets inside too, don't you?
Be careful not to over-amp the motor and risk losing some of the magnetism.
You probably can't totally demagnatize them, but you can permanently reduce it and lose some level of performance.
haha, no - and no. But if I need to I will get it. I'm in too deep to back out now so I might as well start looking for the tools.Do you have, or have access to, test gear such as an o'scope and peak reading current probe?
I agree, but after all thats happened, there doesn't seem to be much choice.All of that considered, it could be a great project to explore.
Mark
Relying on rules like "derate current by 50%" will end up costing you a lot of money with IGBT modules. I generally assume that whatever current rating is given at a realistic case temp (like 70-80C) is an attainable maximum with good heatsinking (e.g. - liquid cooling).So what do you guys think about the IGBT rating verses the actual controller output? What sort of safety net should there be?