| The complex driving conditions of electric vehicles(EVs)require that the driving motor has a wide speed-torque range,maximum efficiency and a wide range of high-efficiency area,i.e.,wide-range high-efficiency.The most direct tool for evaluatingthe design of a driving motor is the motor efficiency MAP.However,the conventional method to obtain the motor efficiency MAP map is time-consuming and laborious,and cannot be obtained quickly in the initial design,in order to evaluate the motor design.To address this problem,this thesis establishes a fast calculation method to obtain the efficiency MAP of permanent magnet synchronous motor(PMSM),and analyzes the performance of the motor based on the fast calculation method.The main contents include:(1)The wide-range high-efficiency design requirements for driving motors are proposed.Combined with the driving conditions of EVs,the driving motor has constant torque characteristics and high torque overload capability below the base speed,so as to adapt to the vehicle's operating conditions,such as quick start,load ramping and frequent start and stop;above the base speed,a wide range of constant power characteristics and a large flux weakening ratio are required to meet the dynamic requirements of the vehicle's maximum speed;maximum efficiency and a wide range of high efficiency are designed to satisfy the energy-saving design features.(2)A motor efficiency MAP fast calculation methodis established.Firstly,based on the equivalent magnetic circuit analysis,the magnetic and motor parameters of the external rotor PMSM are calculated.The stator control current is calculated at different torques and speeds through the introduction of the motor control strategy.Then,the stator control current is used to calculate the loss of the motor under different torques and speeds,so the motor's efficiency MAP can be quickly obtained.(3)Analysis of factors affecting driving motor's wide-range high-efficiency performance is conducted.Using the efficiency MAP fast calculation program,the motor body structure parameters and motor controller parameters that affect the motor wide-range high-efficiency performance are analyzed.The analysis provides theoretical guidance for the design and optimization of the driving motor's wide-range high-efficiency performance.(4)Finite element method simulation of the motor's wide-range high-efficiency performance isconducted.Through the method of finite element method simulation,the efficiency MAP of the motor is obtained,which further validates the correctness and general application of the motor efficiency MAPfast calculation program.(5)Optimization design to improve the motor's wide-range high-efficiency performance is conducted.The genetic algorithm and the MATLAB calculation program are combined to optimize the design of the motor's main body structure parameters and motor controller parameters,with an optimization goal of the motor's maximum efficiency and high-efficiency range ratio.The optimized wide-range high-efficiency performance was further improved. |
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