Sixth torque harmonic in PWM inverter-fed induction drives and its compensation

The sixth-order torque ripple harmonic in induction motors under field-oriented control with voltage space phasor modulation is investigated by means of a simulation model. It is shown that the main reason for its appearance lies in the pulsewidth modulation. Measurements on a 220-kW asynchronous drive confirm the simulation results. A compensation strategy is proposed.