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Old 09-16-2014, 05:25 PM   #1114 (permalink)
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It would take maybe a day of getting a good resolution graph from the waveform, and building a lookup table, where the index of where to look in the table is the A/D value, and the content of the table is the angle. But that would only get you angles where the function is one to one. So, for sine, it would only work from -pi/2 to pi/2. Then, the other table can have just -, 0, + for the other function (is it negative, 0, or positive). From that, you can know the angle, since sin is positive and cos is positive in Q1, sin is positive and cos is negative in Q2, sin and cos are negative in Q3, and cos is positive and sin is negative in Q4.

The SVM doesn't make use of sin and cos at all. It just has Va, Vb, and Vc, which are the voltages along 0 degrees, 120 degrees, and 240 degrees.
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