Demagnetization Analysis of a High-Speed PMSM for an Aerospace Application

As the more-electric aircraft concept is gaining popularity, electric motors such as Permanent Magnet Synchronous Motors (PMSMs) are widely used in various aerospace applications. Though they have high torque and high power density, the presence of Permanent Magnet (PM) makes PMSMs vulnerable to demagnetization faults. This can significantly impact the performance of the machine. Hence a demagnetization analysis should be studied while designing the motor. In this paper, the selection of PM material for a 150 kW, 20000 rpm PMSM designed for an aerospace propulsion application is presented. A finite element 2D and 3D model of the motor is developed. Two NdFeB-PMs are studied for demagnetization under three possible causes: the rise in temperature, large short circuit fault currents and external demagnetizing field. The performance of the magnets with these cases are compared, and the magnet which shows superior demagnetization withstanding capability is chosen for the final design. A step-by-step procedure of demagnetization analysis under these conditions are presented in detail.