A Study on the Design of IPMSM for Reliability of Demagnetization Characteristics-Based Rotor

This paper describes a study on an design of IPMSM (Interior Permanent Magnet Synchronous Motor) for reliability of demagnetization characteristics-based rotor. The IPMSM in this paper is located at a lower part of a railway vehicle and has a totally enclosed type structure so heat does not circulate within it and its temperature rises high. In order to increase power density of the motor, a neodymium permanent magnet with high energy density is used. However, this neodymium permanent magnet has properties that demagnetization occurs at a high temperature or by a reverse magnetic field and that as a new demagnetization curve called a recoil line is drawn in the B-H characteristic curve, magnet becomes permanently demagnetized. This permanent demagnetization property decreases the torque characteristics of or power output of the motor, eventually making it impossible to drive the railway vehicle and also reducing its reliability. In order to prepare for these problems, it is definitely necessary to consider analysis of the demagnetization property in the analysis stage. Hence, this study aims to propose an analysis method of demagnetization characteristics by considering the recoil line and to establish a base capable of securing reliability of IPMSM for traction of and highlights the proposed analysis method through a performance test and temperature saturation test of the prototype.