Why does the motor governor need to set the frequency?

Motor governor frequency is too low, power ripple, motor vibration;The frequency is too high, the switch loss is large, the electromagnetic noise is obvious.If the frequency is not chosen properly, the effective power output of the motor will be greatly reduced.The factory default frequency of this product is 20KHz, which can meet most of the motor requirements.Consult motor manufacturer for specific frequency selection.

Why does a motor governor use a digital encoder knob instead of a normal potentiometer?