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Old 04-07-2009, 07:15 PM   #799 (permalink)
MPaulHolmes's Avatar
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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 think the shudder is probably not the hardware current limiting (unless you were pulling 500 amps). I'm guessing that it is the noisy signal from the current sensor. I'm partially using the current sensor to control throttle, so you are probably feeling the variation in the reads in the input to the A/D converter. I have gotten advice on how to clean that signal up, so it shouldn't be a problem on version 2.

I wish I would have tried this test too, to see if my smaller motor behaves the same. I only drove the car, never spinning the motor in neutral, and I didn't notice a shudder while driving. It will be interesting to see if you notice the shudder while driving or while taking off from a stop.

EDIT: Actually, it's not just noise from the current sensor. The problem is that the motor current isn't constant. It goes up and down, but I'm not reading the current at the same part of the PWM waveform each time, so the current sensor is spitting out values that reflect different parts of the motor current variation. I'll also fix that in version 2.
kits and boards

Last edited by MPaulHolmes; 04-07-2009 at 08:34 PM..
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