A METHOD FOR OPERATING A MECHANICALLY COMMUTATED ELECTRIC MOTOR

摘要

A method for operating a brush commutated electric motor(1). The method comprising the steps of supplying a pulse width modulated supply signal having a first predetermined frequency to said brush commutated motor, and adjusting the duty cycle of said pulse width modulated supply signal to a desired value. The method also comprises the further step of adjusting the frequency of the pulse width modulated signal to a second frequency differing from said first predetermined frequency, while maintaining the desired value of the duty cycle.