Patent ID: 7800333

Claim:
A method for reducing audible motor noise in a motor drive, wherein the motor drive includes a motor controller driving a PWM space vector modulator providing gating pulses to an inverter providing phase currents to the phase windings of the motor, and wherein phase currents of the motor are determined by taking samples of the DC link current in a DC link powering the inverter, the method comprising: determining the speed of the motor and comparing the speed to a preset threshold, said preset threshold defining a speed at which audible noise is generated by the motor due to a minimum pulse constraint being imposed on the motor phase currents in order to reliably sample the DC link current to measure the phase currents; and if the speed is below the threshold, sampling the DC link current in the DC link using a reduced number of current samples for a PWM cycle of said PWM space vector modulator to reduce audible motor noise.