Torque ripple reduction in trapezoidal back EMF machines

Abstract

The widespread electrification has made high efficiency and high torque-to-weight ratio a must in the pumping, rolling, and automotive industries. Brushless direct current motors fill this gap at the expense of a condition called torque ripple, which may cause tear, wear, and a low life cycle. This thesis introduces the fundamentals of motors, magnetic behavior, and the torque ripple condition of brushless direct current motors. It introduces common control schemes along with several ripple reduction approaches. Then, it adapts one of the common control schemes called field-oriented control and implements a feature of voltage injection to reduce the reference condition. Finally, it implements the scheme on a physical test bench and compares its behavior against conventional operation, successfully reducing the 6th harmonic amplitude of the torque output signal by at least 50%.