Comparative analysis of the magnet effects on the permanent magnet BLDC motor performance used in electric vehicles

Abstract

The importance of electric vehicles has increased in recent years due to their environmental friendliness and the growing need for clean energy. The main traction power that provides the movement of these vehicles is supplied by electric motors. Along with other electric motors used in electric vehicles, permanent magnet brushless direct current (PMBLDC) motor could be more advantageous to use for light electric vehicles due to its robustness, simple structure, large torque/volume ratio and high efficiency. These PMBLDC motors are desirable because they contain magnets that have a high impact on power density, efficiency, reliability and controllability. Alnico, Ferrite (ceramic), SmCo, and NdFeB magnets are included on the surface/inner surface or embedded in the structure of PMBLDC motors. Among these, the rare earth element neodymium, iron, and boron (NdFeB) magnets, composed of elements having different densities, are widely preferred because they provide a good magnetic field per volume. In this study, a prototype PMBLDC motor with a nominal power of 2.45 kW was designed, which can be used as a traction motor in small electric vehicles. Each mechanical and electrical design of this motor was determined by the detailed drawings produced using the design program. The permanent NdFeB magnet used in the motor was determined by the parameters affecting the performance of the magnets at different grades of power density, different operating temperature ranges, and varying in thickness (conditions observed under magnet wear, etc.). Its effects on performance were investigated by electromagnetic analysis using the finite element method (FEM) and the optimum value ranges were determined. In addition, the study comparatively evaluated the NdFeB magnet types in the designed PMBLDC electric vehicle traction motor in terms of their best performance ranges at different power density ratings.