Influence of Permanent Magnet Arrangement and Iron Core Material on the Performance of IPMSMs with Strong Magnet for Automotive Applications

Abstract

Recently, interior permanent magnet synchronous motors (IPMSMs) have been mainly utilized as the traction motors of eco-friendly vehicles. Moreover, the permanent magnet used for IPMSMs is an important factor that determines their performance. In general, the permanent magnet with a higher remanence increases not only the magnet torque—which in turn increases the torque—but also the iron loss. A rotor structure that is suitable for the permanent magnet, therefore, has to be researched. This paper uses a virtual permanent magnet (VPM) designed to have higher remanence. The single-layered model with the conventional magnet, the single-layered model with the VPM, and the double-layered model with the VPM are compared to investigate the influence of the arrangement and the properties of permanent magnets on the performance of IPMSMs for automotive applications. In addition, the stack length of the best of these motors is reduced in order to downsize it and reduce its volume, and the iron core material is changed to a low iron loss material in order to improve the efficiency. It is observed that the double-layered model with the VPM produces the highest torque and efficiency. Furthermore, both the downsized model and the model with the low iron loss material have a higher efficiency.