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Old 09-17-2015, 10:26 AM   #2026 (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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I have a command on there (well, I'll send another hex file, because I don't remember if it's on there or not) that captures Va and Ia (phase A current and voltage) at 10KHz. IT only captures about 250 data points for each of them, but it's enough for quite a few cycles. Then from that you just look at the peaks of the voltage and current, and the RPM, which is also outputted, and then plug them into some random formula that tells you the stator inductance. You can run that test several times as the motor speed gradually increases, and it will give the stator inductance at several RPMs. From that we can see how the curve behaves as rpm changes.

If you hit 1 a couple times, it will spin the motor one way. If you hit 2, it will slow the motor down, and then eventually spin the motor the other way. At least in theory. haha. that's what my motor does.

There are several interesting things going on that we need to get to the bottom of. The hardware overcurrent protection is basically a comparator and latching circuit that turns the IGBTs off if the current in any of the 3 phases goes outside of -600amp to 600amp (even for a couple microseconds). That's separate from the undervoltage protection circuit. The undervoltage protection disables the IGBTs if the 5v supply goes below like 4.5v and the 24v supply goes below maybe 22.5v or something like that.
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