Quote:
Originally Posted by jackbauer
I've been running an igbt based controller for over a year now without one problem. Not one. And its quite a "rough" build. I discovered this project and purchased a control board from Paul i think in sept 09. I opted for igbts in the power stage as they offer the ease of drive of mosfets with the ruggedness of a bipolar. Electrical issues aside they are also much more physically robust than pcb mountable plastic cased mosfets. This feature greatly assisted with the hardware build. I was able to use one device as the switch and one with its g-e shorted as the freewheel. This meant i had no parallel device issues to worry about. The 1200v rating also helped with the poor design as its much more tolerant of overshoot than a 200v mosfet. Its driven by a stock control board. No modifications beyond a miller clamp circuit comprising two resistors and a diode. The amount of naysing that went on on another forum when i was building the controller was unreal. One always sticks to my mind. "You won't drive 3 feet with that". Done 1500 miles actually and still counting. Recently upped voltage to 152v lifepo4.
Understand i'm not trying to prove anyone wrong here or say that anyone using mosfets is a moron. The point is that both parts have advantages and disadvantages.
I would gently disagree with the premise of old igbts via ebay beiing useless. The parts i have are fuji 1mbi800-u4l if my memory serves. Quite old 3rd gen devices of 2005 vintage. Purchased from a surplus dealer in Germany for 30 euros each second hand.
When i was having some problems driving the device sucessfully , Jeffrey Jenkins of soliton 1 fame rather criptically posted "There's a reason the solition 1 uses 8khz switching in performance mode". This set me off on the trail of lowering the switching frequency from 16khz that suited the mosfets to 8khz that the "old" igbts just loved  Thanks to paul and the gang for doing the software mods to make it happen.
So in short i'm a happy camper with igbts. Others are likewise with mosfets. Now , the only way to settle this battle of the silicon is a drag race |
Thanks Jack. that makes me happy to hear. could you possibly pm me your power board schematic? i think i understand how it all has to go together, but i want to make sure i'm not missing anything. i'm pretty sure i could get away with a single igbt, but from what i can tell from the data sheet, the Vce increases exponentially (to a point) with higher Ic. My thought is that running three in parallel with drastically reduce the current through each one, and increase overall efficiency.
i've also got some giant SCR's....i wanted to use them for a controller but i don't know how to utilize them and i haven't done enough research on it to know for sure. maybe i can use one as the diode or something (: