The optimum design of the magnetic orientation of permanent magnets for IPMSM under hot environments

Abstract

In this study, we investigate the optimum design for improving the demagnetization resistance of a concentrated winding permanent magnet synchronous motor (IPMSM) by changing the magnetization direction of the permanent magnet under a high-temperature environment. IPMSMs (flat plate type, V-shaped type, spoke type) are investigated by finite element analysis (FEA) using the same volume of the permanent magnet while changing the magnet's width, and thickness and magnetic field orientation angle. FEA found that a V angle of 130° and a changed magnet length of 107% (or V angle of 100° and a changed magnet length of 97%) using an oblique magnetic-field-oriented magnet strike a good balance between demagnetization resistance and torque at 180°C. In the V-shaped arrangement, for a motor with the same magnet length, the demagnetization resistance at a magnetic field orientation angle α = 20° is better than that at α = 0°. The magnetic field orientation angle α = 20° has a magnetic flux density distribution closer to a sinusoidal wave form than α = 0° and is thus effective for reducing torque ripple.