Loss And Thermal Analysis Of Harmonic-Shaped Permanent Magnet Synchronous Motor

Aircraft is widely used in the modern life,and requirements of aircraft performance has gradually improved with the development of the society.However,traditional aircraft has low efficiency and low reliability,and can also result in the greenhouse effect,so the single-energy-all-electric aircraft emerged at the historic moment.For all-electric aircraft,the driving motor is the core component,which has high performance requirements.As a high efficiency motor,permanent magnet motor is the first choice to be the driving motor.Harmonic-shaped permanent magnet synchronous motor is a motor applying the harmonic-shaped method to the design,which can greatly improves the torque density of the motor.However,the improvement of torque density often means that the loss and temperature increase,and the heating problem of the motor directly affects the lifetime and reliability of the motor.In this paper,a series of studies and experiments are carried out on the loss and thermal analysis of the third-time harmonic-shaped permanent magnet synchronous motor.Firstly,in this paper,to improve the performance of the harmonic-shaped permanent magnet synchronous motor,the edge thickness and magnetization of permanent magnet are optimized.The electromagnetic performance under different magnetizations are analyzed and compared,and the optimal shape and magnetization are selected.Based on the optimal model,the following study is conducted.Considering the third harmonic component introduced in the airgap flux density will result in variation of flux density distribution in the stator laminations,and then change the losses and thermal field,this paper analyzes flux density and losses of the stator lamination by analytical method and finite element method.The results show that when the fundamental amplitude keeps the same,the influence of 3rd harmonic on stator flux density and losses is related to slot-pole combination.When the maximum thickness of the permanent magnet is maintained,3rd harmonics will increase the stator flux density and losses.Based on the heat transfer theory,the heat transfer path of the motor is analyzed,and equivalent lump parameter thermal model and steady thermal finite element calculation model are established according to the results of the losses discussed above.And the thermal field distributions on no-load and load are obtained.Thermal fields of sine-shaped motor and 3rd-harmonic-shaped motor are compared and the influence of 3rd harmonic on thermal fields is analyzed.Lastly,experiments of harmonic-shaped motor are carried out.Back-EMF and torque are measured to validate the correctness of theoretical analysis.The losses of the motor are measured using power analyzer and the temperature of windings in the motor is obtained by the method of embedding thermometry components.All the experimental results are analyzed and compared with related calculated results and good consistency is shown.