Hello, Erik!
Erik Christiansen wrote:
While fooling with FET drive for a 200 watt DC motor, there was a fair
howl emanating from the motor when the PWM frequency passed through
mechanical resonances. I've read of ruined bearings in large motors, due
to arcing through the lubricant, due to voltage build-up on the rotor,
apparently exacerbated by peaky drive, but the wear effects of
continuous high frequency mechanical vibration doesn't seem to be
mentioned much.
This is really OT.
I did some motion control with high-end motion controllers
from Delta Tau about two years ago. There are ton's of Amplifier
Manufacturers for DC Brushless motors i.e. (i.e. ELMO Flute) Check their design and
you will see that they have (sometimes) some pretty complex Filters mainly to
improve the loop stability, but also to reduce EMI.
You could also contact some Motor Manufacturers (i.e. Maxon) and ask
them about their opinion, but I guess they will just tell you that everything is fine,
as long as you use their motors. :-)
But please, that's too complex to be discussed here. Find a proper list
for your questions.