Loss Analysis And Efficiency Research Of Surface Mount Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)is widely used in new energy vehicles because of its high efficiency,simple structure,high power factor and good control performance.However,its power loss often leads to the temperature rise of the motor,which also has an important impact on the steady-state operation efficiency of the motor.In this paper,the loss and steady-state operation efficiency of permanent magnet synchronous motor are analyzed and calculated in detail,and the influence of various parameter changes on the loss is discussed.Based on the typical vector diagram of permanent magnet synchronous motor,the steady-state efficiency map of the motor is calculated.Completed the motor matching design.According to the basic performance parameters of the motor,the main size of the motor,the rotor pole structure and the materials of the stator and permanent magnet are selected to determine the original electromagnetic scheme of the motor.The two-dimensional model of the motor is established by using Ansys EM finite element software,and the magnetic line of force,magnetic density distribution,output torque and back electromotive force of the motor are simulated and analyzed to verify the rationality of the motor design scheme.The relationship between eddy current loss and slot width is studied.A two-dimensional motor model with different stator slot width is established,combined with the theory of harmonic magnetic field and Maxwell equations,the influence of slot width on rotor eddy current loss is discussed.With the increase of slot width,the differential of the magnetic vector potential with respect to time at the same point of the rotor increases,that is,the induced eddy current density increases;affected by the skin effect,the eddy current is concentrated on the outer surface of the rotor;the relationship between rotor eddy current loss and slot width is quadratic function.The influence of stator tooth shape on motor performance is studied.The radial,tangential and frequency domain decomposition of magnetic flux density at different positions of stator teeth and yoke are carried out,and the harmonic magnetic field ellipse is drawn.The middle and yoke of stator teeth are mainly affected by the alternating magnetic field,while the top and root of stator teeth are affected by both the alternating magnetic field and the rotating magnetic field;the pole-arc coefficient of the permanent magnet is optimized,and the comprehensive performance of the motor is optimal when the pole-arc coefficient is 0.74.Based on the above research,the steady state vector diagram of permanent magnet synchronous motor is deeply analyzed and the phase voltage,phase current and power factor Angle are calculated,the loss of each part of the motor is calculated by two-dimensional finite element software,the calculation and simulation results are fitted in Matlab,the steady-state efficiency diagram of the whole working range is obtained,and compared with the finite element simulation results The calculated efficiency of the motor under rated condition is 94.56%,and the efficiency of the finite element simulation motor is 94.81%;the results of the surface fitting motor efficiency map are consistent with the finite element simulation results,the conclusion is confirmed.