Loss Analysis And Electromagnetic Optimization Of High Power Permanent Magnet Synchronous Motor In Electric Vehicle

Permanent magnet synchronous motor(PMSM) used in electric vehicle, which has small volume and limited installation space, usually operates variable working conditions. With the increase of motor power and motor speed, the temperature rise becomes increasingly prominent and effects on the performance and life of motor. It has important engineering significance to study how to reduce high power density and high speed motor losses for higher efficiency.The stator core loss is one of PMSM losses, colsely related to magnetic flux density changes and frequency. Studied stator core flux density rotational magnetization and higher harmonics in rated operating conditions (50kW,3000r/min) and peak operating condition (85kW,9000r/min) with orthogonal decomposition and fourier transform. Based on a rational core loss model, the central part of teeth loss and yoke loss were calculated. Compared with software simulation value, the central part of teeth and yoke loss based on model respectively increased by 4.2%and 3.2% under rated operating conditions, and increased by 8.2% and 7.4% under peak operating condition.From the perspective of electromagnetic structure, studied the influence level of main size parameters of permanent magnet, stator and rotor punching on core loss and determined the five size parameters as optimization variables. Based on Ansoft parametric function, obtained a better electromagnetic structure which meets the requirements of the electromagnetic torque, the lesser core loss and the higher efficiency. Compared with privious motor performance, the optimized motor core loss reduced by 8.1% and efficiency increased by 0.05% under rated operating conditions; and the core loss reduced by 19.1% and efficiency increased by 0.59% under peak operating conditions. The optimized motor stator core teeth flux density waveform was improved. Based on optimized electromagnetic structure, further research about electromagnetic characteristics of motor with different turns winding was carried out. Winding turns change has an important effect on the motor torque and efficiency.Temperature rise test of prototype verification was done. The motor temperature performance with optimized electromagnetic structure was better. The motor steady-state temperature reduced by 1℃ under rated operating conditions and the duration increased by 3s under peak operating condition.