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Originally Posted by MPaulHolmes
I was actually switching at 10KHz.
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Sorry - I relied on my faulty memory. Thanks for the correction
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The good news at least on my end so far is, this layout hasn't had any problems in the DC case, and that's been with current up to 1550amp at maybe 160v.
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The largest motor I can test (at least, I'll try to test) is 400VDC bus (maybe 280 VAC) with 300 amps continuous. I'm not sure what over-current the motor can take for 10 - 30 seconds, but I hope at least 3X. I hope the DC motor that will be coupled to it can put out that sort of power for 10 - 30 seconds .. before it melts
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I had set the DC controller's PWM frequency to like 4KHz at one point (on accident), and it was making some of his instrumentation go bonkers. When it was changed to 10KHz (and 9-12kHz in the spread spectrum case), that problem went away.
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Good info. My wiring is pretty hideous, especially in testing. So any potential problems with noise *SHOULD* be a problem for me during my testing.
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It may help that the control stuff is several inches away from the high power switching, and the face of the high power switching is a copper sheet rather than a cable. There's almost no loop area between the copper sheets. The sides where the radiation can leak out is small and far from the bulk of the control board. It will be very interesting to see how things go at higher voltage and current. I've only tested it at 20 amps and maybe 120 volts. I hope the results are similar to the DC controller, as the layouts are the same.
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I remember the discussions - you agonized over a *LOT* of details. I'm not saying that we will have problems. I'm not questioning your design. I'm a paranoid .. I'm actually *TRYING* to have noise problems during testing so that when you wire neatly and follow some rules .. we should never see any issues.
Onward!