Smooth Voltage PWM for Vibration and Acoustic Noise Reduction in Switched Reluctance Machines

This article proposes and investigates a control technique for vibration and acoustic noise reduction in Switched Reluctance Machines (SRMs). A large vibration generally occurs at the turn-off stage of SRM phase voltage due to a sudden decrease in the attraction force. The proposed technique is a smooth voltage Pulse-Width Modulation (PWM) method that utilizes the PWM technique to reduce the rate of change of voltage during the turn-off commutation angle. The aim of this proposed method is to control the vibration with high PWM frequency at the very beginning stage when the vibration is low before being developed into higher amplitude at the turn-off stage, without having to generate anti-phase vibration. Both simulation and experimental testing are implemented to confirm the capabilities and limitations of this technique.