Yes, there is a particular frequency that the motor works better, and
that value should be find by experiment in a dynamometer or something
like that.  Lots of variables set that particular frequency, including
the inertia and vibration (and reverberation) at the motor ball
bearings. Just to start to think about it, imagine your pwm signal being
ON for 10 seconds, and OFF for 30 seconds, so your pwm would be 25%,
right? It will be not the right frequency (0.025 Hz) and the motor will
act in an undesireble way.  Also using 2.5GHz will cause strange motor
behavior, so it means that the right frequency is in between somewhere.
Everyone sits in a different spot on the beach, also the motor pwm
frequency.

Wagner

Jinx wrote:
>
> From: soon lee <psln@CYBERWAY.COM.SG>
>
> > Hi    guys
> > got a question here
> > is there a standard for the value of PWM frequency for motors and how you
> > determind it??
> >
> > thanks
> > regards
>
> I'm not too sure, but one factor to consider is the audible noise that
> comes from motor at the freq you drive the PWM at. Does a motor
> resonate at a particular freq, like a speaker ? If so, is this affected
> by the number of poles, or whether a motor is electro- or permanent
> magnet type ?
>
> I noted Russell McMahon's comments about the rotor losing touch
> with the magnetic fields as the frequency is increased. This would
> seem to imply that there's an optimum range of driving conditions.
>
> Jinx