Voltage Imbalance Correction Using Trapezoidal Modulation in Asynchronous PWM

Abstract

Permanent magnet synchronous motors (PMSMs) generate torque ripple through the pulse width modulation (PWM) method of voltage source inverters. In this report, we propose a method to reduce torque ripple during overmodula- tion in asynchronous PWM. In asynchronous PWM, when the number of pulses decreases during high-speed rotation, three-phase voltage imbalance occurs and torque ripple occurs. By controlling the PWM pulse edge using trapezoidal wave modulation, seamless control from asynchronous PWM down to a single pulse can be achieved. The effectiveness of the proposed method was confirmed by its simulation and experimental results.