After a lot of research and simulation tries, I cannot determine how a brushed DC motor would act if given a high PWM frequency, ignoring any losses in the controller due to switching.
What I know so far: When a brushed DC motor recieves low frequency PWM, there will be a current ripple and a reduction in effeciency. Increasing the frequency reduces ripple amplitude, and it is generally adviseable to go above 20 kHz if driving with high frequency to avoid audible noise. A basic model of a DC motor is an inductor, a resistor, and back EMF.
However, I cannot find information for what happens at higher frequncies. I believe that the motor also has a capacitance (other than any capacitor that may be added to reduce EMI). So, at what frequency range can a typical motor be driven efficiently and without reduced speed and torque?
If even in the MHz region the capacitance is so small that it is negligible , then I would expect the DC component to not be attenuated, while the AC component of the PWM signal would become negligible. This would possibly allow PWM drive without significant current ripple, needing only small ceramic capacitors and thus a smaller driver board, ignoring switching losses.
I was not able to simulate this, and I dont have the equipment to test it. I would appreciate any help. Thank you.