Finite element demagnetization analysis of permanent magnet synchronous motor considering magnetization process

The paper deals with the two-dimensional finite element analysis (FEA) for the irreversible demagnetization characteristics of a rare-earth permanent magnet in the permanent magnet synchronous motor (PMSM). The motor is designed for electric power steering (EPS) of automotive application. The irreversible demagnetization has been carried out for high temperatures due to an external magnetic field during the specified test procedure for EPS. At first, the magnetization model using a special magnetizing fixture is employed to analyze the proper distribution and radial orientation of the magnetization vectors in the radial anisotropic ring magnet. The nonlinear demagnetizing curves for permanent magnet as well as the influence of temperature on the demagnetization have been taken into account. Also the nonlinear BH characteristic of the magnetic iron core is considered. The described coupled field analysis has been performed using the commercial finite element software ANSYS Multiphysics. Finally, the obtained simulation results with good accuracy have been verified by comparing with performed measurements.