TMS320F28069M: High Speed motors

The pwm frequency depends on motor's maximum electric frequency, expected speed/torque control precision and MOSFET/IGBT. The maximum electric frequency of your motor is 1750Hz, so the pwm frequency should be higher than 31.5KHz, 41+KHz is more better.

The voltage filter pole frequency is calculated from voltage sampling circuit, it must meet >200Hz, >IQ_FULLSCALE_FREQUENCY_Hz/4. So in your case, the USER_VOLTAGE_FILTER_POLE_Hz must >437.5Hz and < 875Hz.

Yanming,

Could you point to some rules of thumb you are using to go from 1750Hz to 31.5kHz?

Thanks,

-- Will

No any critical rule, only need the pwm frequency is more bigger than the IQ scale frequency, it's better to be an integer multiples.

Thanks for the response. Could you elaborate?

Curious because I don't see the integer multiplier between 1750Hz and 31.5kHz (or 41kHz). It looks like a factor of around 15-20 above fullscale frequency?

I assume the to stay above Is the goal to keep the PWM at least a decade above both the electrical frequency and the filter?

Right. Only need to set the pwm frequency is more than 12 times than maximum electric frequency, even non-integer multiplier. 3*N multiple is just a prefer value, you can set any pwm frequency according to your hardware.