Design And Flux-weakening Performance Of Hybrid Permanent Magnet Synchronous Reluctance Motor For Vehicle

Drive motor for vehicle is the central component of electric vehicle.Motor type selection and design are the key factors that determine the performance of electric vehicle.Permanent magnet synchronous reluctance motor is one of the common types of drive motor for electric vehicle,which has the characteristics of wide speed regulation range,high power density and low permanent magnet consumption.In order to further improve the output characteristics of this type of motor in a wide speed range,this thesis analyzes the influence of rotor structural parameters of permanent magnet synchronous reluctance motor on torque performance,and studies the use of hybrid permanent magnet to improve the power and efficiency in the fluxweakening operation region.Firstly,in order to clarify the influence mechanism of key structural parameters of permanent magnet synchronous reluctance motor,a scheme of permanent magnet synchronous reluctance motor is designed.The effects of rotor structural parameters such as the number of flux barrier layers and the thickness of flux barrier on the torque density are analyzed.Secondly,based on the Lorentz force law,the generation mechanism of torque ripple of permanent magnet synchronous reluctance motor is clarified,and it is obtained that the torque ripple of the motor comes from the interaction of stator and rotor magnetomotive force harmonics of the same order.The harmonics of stator magnetomotive force with two pole-slot combinations are calculated.Based on the magnetic circuit method,the rotor magnetomotive force with three flux barriers is calculated,and the main influence factors of the rotor magnetomotive force are obtained.The influence of the end position of flux barrier on the torque ripple and average torque under two pole slot combinations is analyzed.The influence of four equal permanent magnet placement methods on the rotor magnetomotive force and torque ripple is considered.Finally,aiming at the problem of high power in the flux-weakening operation region but low efficiency in the high-speed and low-torque operation region of ferrite and Nd Fe B hybrid permanent magnet synchronous reluctance motor,the design method of the ferrite,Nd Fe B and Al Ni Co hybrid permanent magnet synchronous reluctance motor is studied,the efficiency of the motor in the high-speed and low-torque region can be improved to a certain extent without reducing the power in the flux-weakening operation region.Considering the flux-weakening rate and flux regulating current,the relative amount of Al Ni Co and Nd Fe B is designed.By analyzing the flux regulation process of the motor,the maximum and minimum magnetization states are determined,and the efficiency distribution and other relevant electromagnetic characteristics are analyzed.