Irreversible Demagnetization Fault Diagnosis of Permanent Magnet Synchronous Motor for Electric Vehicle

Recently, researchers have an interest on the electric vehicle because it is more eco-friendly and efficient than gas vehicle. Instead of a gas engine, the electric vehicle has a motor for propulsion. The permanent magnet synchronous motor which has permanent magnet instead of field winding in the rotor has especially higher efficiency and torque per weight than other types of motor. When the irreversible demagnetization is occurred, users can be expose to high risk of accident by the fault operation of motor. Because of this, the irreversible demagnetization of permanent magnet should be detected by using any kinds of method to reduce the risk of accident. In this study, the demagnetization diagnosis method based on the result of locked rotor test is proposed. Base on short measurement time, the proposed diagnosis method aims to detect the demagnetization fault when the electric vehicle is at a complete standstill. The proposed method is verified by using the finite element analysis.