Performance Analysis of a Surface Mounted Permanent Magnet Brushless DC Motor Using an Improved Phase Variable Model

This paper presents the performance analysis of a high-speed surface mounted permanent magnet (PM) brushless DC motor by using an improved phase variable model. Magnetic field finite element analyses are conducted to accurately calculate key motor parameters such as air gap flux, back electromotive force and inductance, and their dependence on rotor position and magnetic saturation. 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. In the model, the rotor position dependence of the 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.