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Old 08-25-2014, 12:42 PM   #1013 (permalink)
MPaulHolmes
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Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000
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Software-wise, the differences are actually very minor. The main difference is computing the rotor flux angle. In the pmsm case, it's the rotor angle, so you just need to read the dang angle! In the acim case, you have to make a running guess at the rotor flux angle, using some formula that makes no sense to me. haha. In fact, it's the only formula from start to finish that I didn't derive myself. That bothers me, as it's hard to look for bugs when you are doing things that don't make sense. I haven't tried to make sense of it in several months, and I haven't tried that hard, so maybe I should give it another go. One interesting fact about the formula is, you cannot use it when the motor isn't turning, so FOC is useless at zero rpm. You need to use some sort of thing like V/HZ to get it turning, and then switch over to FOC. Otherwise, that formula divides by zero!!! NOO!!!

The PMSM motor also uses a resolver. If the motor is turning at 6000rpm, you'd have to check the angle at about 6.4KHz in order to get a resolution of 5 degrees (64 ticks per revolution). I think that's doable.
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Last edited by MPaulHolmes; 08-25-2014 at 12:47 PM..
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