Design And Simulation Optimization Of Permanent Magnet Brushless DC Motor For Low Speed Pure Electric Vehicles

Low-speed electric vehicles are characterized by low pollution,low cost,low technical requirements and large market demand,which make them have good development prospects.The performance of the motor drive system is an important indicator to measure the quality of low-speed electric vehicles.Hub motors have the advantages of simplifying the system structure,improving transmission efficiency and independent control,etc,and have become an important direction for the development of electric vehicles.As a low-speed hub drive motor,the torque ripple of permanent magnet brushless DC motor is relatively large,so reducing the torque ripple is one of the main research directions in the optimal design of permanent magnet brushless DC motor.Based on the basic structure and working principle of permanent magnet brushless DC motor,this paper analyzes the basic equation and mathematical model of permanent magnet brushless DC motor,and proposes the design scheme of outer rotor hub direct drive motor.Then,according to the power performance requirements of electric vehicles,a direct-drive three-phase 32-pole 5kW permanent magnet brushless DC hub drive motor is designed.The Ansoft Maxwell software is used to model and analyze the motor.Some parameters of the motor are simulated and analyzed parametrically.The influences of pole arc,permanent magnet thickness,iron core length and multi-parameter coupling on the torque of the motor are discussed.The motor parameters are determined by using the principle of minimum torque ripple.The effects of cogging torque and magnetic field radial force on torque ripple are further discussed,and quantitative analysis results are given based on simulation analysis.Using the average torque as output variable,the relationship between input and output under the least squares support vector machine is established,and the sample space is established,and compared with the finite element simulation.Finally,the improved genetic algorithm based on simulated annealing method optimizes the parameters of the motor,and compares the motor performance before and after optimization.The optimization results show that the torque of the permanent magnet brushless DC motor has been improved,the torque ripple is suppression.Thus verifying the feasibility and effectiveness of the optimization.