Design And Analysis Of Double-layer Built-in Permanent Magnet Synchronous Motor With Hairpin Winding

With the development and progress of the times,human demand for energy has increased significantly.The rising price of fossil energy and the damage to the environment have become the problems that must be faced by the development of human society.The concept of green economy and environmental protection has gradually gained people’s attention and recognition.In terms of travel,new energy vehicles are considered to be the future development direction of vehicles because of their advantages of zero emission and high efficiency.As a key part of new energy vehicles,the performance of drive motor directly affects the dynamic characteristics of vehicles.Permanent magnet synchronous motor has become a hot spot in the field of electric vehicle drive motor because of its simple structure,long service life and high efficiency.According to the requirements of high efficiency and high power density of new energy vehicle drive motor,a card winding double-layer permanent magnet built-in permanent magnet synchronous motor is designed in this thesis.Firstly,according to the design index of drive motor and the basic equation of permanent magnet synchronous motor,a two-dimensional finite element model of motor was established.The effects of hairpin winding size,stator slots height and width on winding eddy current loss and torque performance were analyzed by finite element method.The permanent magnet size of double-layer v-pole was designed by Taguchi calculation method,By analyzing the output performance of the motor under different inclined pole segments and inclined pole angles,the segmented inclined pole design of the rotor was determined.Secondly,the no-load back EMF,no-load air gap flux density,cogging torque,magnetic field distribution and output torque under rated load were simulated by finite element method;By calculating the losses of the motor,the efficiency map of the motor under different working conditions was obtained;In order to ensure the safe operation of the motor at the maximum speed,the equivalent stress of the motor rotor at high speed was calculated by using the statics module in the finite element software,and the mechanical strength of the rotor is checked.The results show that the electromagnetic and mechanical properties of the motor can meet the design requirements.Finally,the mechanism of demagnetization of permanent magnet material in the motor was analyzed.According to the characteristics of large armature current and high working temperature under peak working condition,the demagnetization of permanent magnet under peak working condition was calculated and analyzed,and the working point of irreversible demagnetization was obtained;The relationship between the demagnetization of permanent magnet and the effective value of armature current,the working temperature of permanent magnet and the angle of current leading back EMF was analyzed.