Analysis of Axial Temperature Variation Effect on the Performance of Five-Phase Permanent Magnet assisted Synchronous Reluctance Motor

Abstract

This paper presents the impact of magnet axial temperature variation on the electromagnetic performance of a five-phase permanent magnet assisted synchronous reluctance motor (PMaSynRM). The torque performance, manet demagnetization, vibration, and control of permanent magnet (PM) machines are highly dependent on the PM temperature variation. Commonly, in machine control, an average radial magnet temperature is estimated and used, while the temperature variation along the axial direction is assumed as uniform. However, in practice, the magnet axial temperature variation is not uniform, and it can lead to unbalance magnetization, localized magnet hot-spot, increase in torque ripple, and machine noise. These effects can be even more crucial in the high-speed and high-power density machine. In this study, the non-uniform PM axial temperature distribution has been estimated by using a novel axial thermal model adopting the finite volume method (FVM). Furthermore, its effects on the machine performance, especially back EMF, radial force, and torque ripple, have been investigated using the 3-D FEA model. The estimated and simulated results have been validated by an innovative wireless experimental setup.