Analysis of Magnetization Characteristic Based B-H Curve Fitting According to the Operation Conditions for Traction Motor

This paper examines the demagnetization characteristics of rare earth permanent magnets (PMs) used in electric machinery. An analytical model was designed considering a controllable shape, temperature, and the external magnetic field in PMs used in the rotor of an interior permanent magnet synchronous motor (IPMSM) for driving an electric railway vehicle (ERV). The demagnetization process was analysed based on the magnetization and demagnetization theory for PM materials in computer simulation. The result of the analysis can be used to calculate the magnetization and demagnetization phenomenon according to the input B-H curves. So, this paper presents the conditions of demagnetization by the external magnetic field in the running and stopped states and proposes a simulation method that can analyse demagnetization phenomena according to each condition and be used to design the IPMSM that maximizes efficiency and torque characteristics. This was experimentally verified.