A Study on the Performance and Demagnetization Characteristics of an Interior Permanent Magnet Synchronous Motor According to the Arrangement of Permanent Magnets

Interior permanent magnet synchronous motors (IPMSMs) are widely used as traction motors in electric vehicles (EVs), with performance largely dependent on the arrangement of the permanent magnets. Rare-earth permanent magnets can weaken under high temperatures and external magnetic fields due to demagnetization, making it essential to consider both performance variations and demagnetization effects when designing these motors. This study investigates a 40-kW IPMSM with a V-shaped permanent magnet arrangement, focusing on its magnetic flux characteristics. To assess how magnet arrangement influences performance, two alternative models were developed with bar- and delta-shaped magnet configurations. Finite element analysis was used to evaluate their performance, while a demagnetization analysis was conducted to compare reductions in back electromotive force across the different designs. The temperature conditions for the demagnetization analysis were determined through thermal simulations. Despite having the same total permanent magnet area, the models exhibited distinct motor and magnetization characteristics. The V-type model demonstrated greater resistance to demagnetization, the bar-type model achieved higher output power, and the delta-type model provided improved control performance.