Torsional Resonance Noise Reduction by Motor Torque Phase Adjustment

A Hybrid Vehicle (HEV) and an Electric Vehicle (EV) are some of solutions to improve efficiency of a cruse and to reduce CO2 gas by regenerative breaking and operating the engine in optimum condition. It is requested to decrease the motor size and to increase the maximum torque for minimizing the driving units. For these purposes permanent magnet applied motors have been commonly used recently. The motor driving systems of HEV or EV must operate at variable speed ranges of up to 1:5. For this large range, Silent and smooth operations are desirable and important. Skew method is often adopted to ensure smooth start and stop and silent operation by reducing the torque ripple. But it possibly causes noise and vibration of the motor. This paper describes the mechanism of torsional resonance noise and vibrations arising from the skew method and the countermeasure to decrease them.