How do you choose a PWM Frequency to drive a DC motor?
As already mentioned, you want the PWM period to be much shorter than the L/R time constant of your DC motor to better approximate constant current for a given setpoint. I'll just add that the other side of the trade is that as you go to higher and higher PWM switching frequencies, your controller FETs (in your H-bridge) start dissipating more power because their ~fixed switching time is larger as a percentage of the PWM period.