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Old 01-20-2011, 04:05 AM   #4235 (permalink)
MPaulHolmes's Avatar
Join Date: Feb 2008
Location: Maricopa, AZ (sort of. Actually outside of town)
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Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000
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Exactly squiggles. A guy on here from the frozen north had a similar issue happen. The pedal contactor engaged after there was already some throttle. It could even be as simple as if pwm > x and current < y, then FAULT. I was hesitant to add it though, because I wasn't sure about a situation like very high revs down a hill or something. Couldn't it happen that pwm is very high, and the current is very small under healthy conditions? Just when the rpm is sufficiently low would it be a problem?

Hey DJ Becker! I was just thinking that because I'm limited to 3 and 4 ounce copper right now, that I shouldn't push too much current through too short of a board. I was thinking that 100 amps per leg was asking for trouble with the solder joints and the pcb tracks. I thought if I could just make the board a bit longer and use maybe 14 of the irfp4668's instead, which would keep the current down. Man, there are schottky 200v diodes in a TO-264 package that are rated for 250 amps. An almost perfect match to the TO-264 gigamos mosfets that are rated for 230amps. My main reason for doing SR before was because I couldn't find any diodes that matched the current of the mosfets.
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