Comprehensive Performance Evaluation of a High Speed Brushless DC Motor Using an Improved Phase Variable Model

Abstract

This paper presents the performance evaluation of a high-speed surface mounted PM brushless DC motor by using an improved phase variable model. Magnetic field finite element analyses are conducted to accurately calculate the key motor parameters such as air gap flux, back electromotive force and inductance, and their dependence on rotor position and magnetic saturation. Based on the numerical magnetic field solutions, a modified incremental energy method is applied to effectively calculate the self and mutual inductances of the stator windings. In order to evaluate the comprehensive performance of the motor, especially the motor output at high-speed operation, which is affected by the dynamic inductances, an improved phase variable model is derived to simulate the motor performance. In the model, the rotor position dependence of key parameters is taken into account. The motor prototype has been constructed and tested with both a dynamometer and a high-speed embroidery machine, validating successfully the theoretical calculations.