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Unread 05-01-2011, 02:32
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Ether Ether is offline
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Re: Modeling motor control

Quote:
Originally Posted by kamocat View Post
Thank you for the straightforward answers.

How would I measure it in a way that any waveform with the same current would create the same torque? You said algebraic average?
That's a fair question but the answer has a lot of ifs, ands, and buts.

If the waveform is nice and flat like a 5% 15Khz CIM curve then any sample taken with be both the algebraic average and the RMS, approximately.

If the waveform is an exaggerated sawtooth like a 5% 150Hz CIM curve, then you'd have to sample the instantaneous current and run it through a low-pass filter of some sort. You'd have to make sure your samples captured a reasonable picture of the entire waveform and were set up in such a way that aliasing didn't distort the results. OR, I think a better way would be to hardware-filter the raw analog signal (the amplified voltage across the shunt resistor) before it goes to the ADC. I think a filter could be designed that would give the algebraic average.



Last edited by Ether : 05-01-2011 at 02:48.