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Old 04-01-2014, 11:29 AM   #6374 (permalink)
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Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000
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By the way, I'm planning on running it at 8KHz PWM, which is audible. If it turns out to be a problem, I'll have to go with software PWM, and spread spectrum switching. It's just that the IGBTs are so big, that they really can't switch all that fast. But if you have software PWM, then you can have the pwm frequency spread over a range of values: 7.800 kHz, 7.801kHz, ... 8.200kHz, etc.. At this point I don't know how much the frequency has to vary for it to be effective.
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