Impact of PWM Control Frequency onto Efficiency of a 1 kW Permanent Magnet Synchronous Motor

The paper explains how to select the best PWM control frequency for specific Permanent Magnet Synchronous Motors (PMSM) to achieve its maximum efficiency. Examinations were carried out for a PMSM unit with the power of 1 kW, rated speed of 1000 rpm and rated torque of 6 Nm. The PWM frequency ranged from 4 kHz to 20 kHz with the increment of 1 kHz. Measurements were taken for each of the foregoing frequencies, for the load torques of 2 Nm, 4 Nm and 6 Nm and for the rotation speeds of 300 rpm, 500 rpm, 750 rpm, 1000 rpm and 1200 rpm to find out efficiency of the PMSM motor. The achieved results make it possible to properly adjust the PWM control frequency for each PMSM motor to operate the motor in the most efficient way and, in consequence, save energy consumed by that motor.