Research On Electromagnetic And Temperature Rise Characteristics Of High Torque Density Permanent Magnet Synchronous Motor

Solar unmanned aerial vehicles(SUAV)have attracted more attention internationally due to their high military,civil and commercial value.In order to improve the endurance and payload carrying capacity of SUAV,its propulsion motor must achieve high torque density and meet strict efficiency indexes at different working points.Meanwhile,due to the difference between high altitude and ground environment,it is increasingly important to check and analyze the heat dissipation and temperature rise of the motor.Based on the background of SUAV propulsion,this paper studies the electromagnetic and temperature rise characteristics of high torque density motor.Firstly,in order to quickly analyze and accurately calculate the performance of the motor,the torque calculation model of the surface magnet synchronous motor is established based on the equivalent magnetic network method,and the application scope of the equivalent magnetic network model is extended by combining the existing air gap magnetic field analysis method.After verifying the accuracy of the model,the influence law of electromagnetic load,the pole and slot combination and magnetic pole structure on torque density is analyzed with the model.Secondly,the loss of permanent magnet synchronous motor is calculated by the equivalent magnetic network model,and the accuracy of the calculation results is verified by finite element and experiment.Then,based on the advantages of fast calculation of equivalent magnetic network,on the basis of obtaining electromagnetic torque and loss,the influence law of motor torque density on loss and efficiency at different working points is summarized and analyzed from the perspective of loss distribution.The effect of pole number on the relationship between torque density and efficiency is analyzed.After that,the changes of environmental conditions and air physical properties within the range of SUAV operation space are analyzed.The convective heat transfer coefficient and its distribution on the surface of the motor were calculated by analyzing the fluid field of the motor.On this basis,the influence of atmospheric temperature and air density on convective heat transfer coefficient in high altitude environment is analyzed.By means of the heat pipe sample test,the change rule of its thermal conductivity under low temperature environment is obtained,which provides the basis for the analysis of motor temperature rise.Finally,based on the analysis of the motor loss and heat dissipation conditions,the temperature field analysis model of the stator of the motor was established to calculate the temperature rise of the motor in the high-altitude environment,which is compared with the experiment.The influence of the heat pipe-fin structure and the pole and slot combination on temperature rise of motor was analyzed.