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.
OK, I could keep the frequency fixed, and above 20 kHz, but that only minimises the vibration. Filtering the drive's output would silence the motor, but would longevity be noticeably improved, I wonder? (Any anecdotes would be most informative. :-) Erik _______________________________________________ AVR-chat mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/avr-chat
