Research On Optimization Of Heat Source Loss Of Electric Vehicle In-wheel Motor Based On Game Theory

The rapid development of electric vehicles has made great contributions to the sustainable development of society.In recent years,in-wheel motor drive systems have made significant progress in the field of electric vehicles.However,due to the structural factors of the in-wheel motor,the heat generated by the loss conversion during operation is not easily dissipated to the outside,which causes the temperature in the motor to rise too fast,which affects the performance and life of the motor.Therefore,it is of great significance to optimize the structure of the motor and reduce its heat source loss during operation.Firstly,the calculation method of heat source loss of permanent magnet synchronous motor(PMSM)core loss,winding copper loss,permanent magnet eddy current loss and friction loss is theoretically deduced;the simulation software Motor-CAD is used to calculate the heat source loss of the motor under different working conditions;combining theoretical derivation and software simulation,the influence of motor structure parameters on its heat source loss is studied.Secondly,the equivalent thermal network analysis model of the PMSM is established,and the calculation method of the thermal resistance of each node of the motor and the motor temperature field is deduced;the iterative calculation method of the heat source loss and the temperature field considering the temperature factor is proposed;an improved equivalent thermal network coupling analysis model is established;MATLAB software is used to write a program to solve the thermal resistance and temperature of the motor node;the motor simulation model is established by Motor-CAD to verify the thermal network model.Then,the basic theory of game theory and the application method in multi-objective optimization problem is introduced;based on the improved particle swarm optimization algorithm,game torque and spatial distance,a game strategy set partition method is proposed;the Nash equilibrium game model is used to solve the problem of optimal design of heat source loss of in-wheel motors;a multi-objective optimization design method based on Nash equilibrium game model is proposed.Finally,the proposed multi-objective problem optimization method based on game theory is adopted to the optimization of in-wheel motor,the heat source loss and efficiency of the in-wheel motor are used as the optimization goals,the size parameters of the stator slot shape are used as the variables;simulation results before the optimization are compared separately with the ones after the optimization aiming at three aspects including efficiency maps built in Motor-CAD,steady state temperature fields in stator slot analyzed by FEA and temperature distributions of the PMSM,the results also verify that the calculated values of the motor losses and temperature field are consistent with the simulation results.Through the research on the multi-objective optimization problem of heat source loss of in-wheel motor based on game theory,it shows that the results obtained by using the method of combining theoretical derivation and experimental verification to analyze the influence of motor structure parameters on heat source loss are more accurate;the results obtained by using the calculation model established by the improved equivalent thermal network coupling analysis method are more consistent with the actual situation;the results obtained by using the improved equivalent thermal network coupling analysis method are more accurate;the multi-objective optimization method based on game theory can not only fully consider the relationship between each player,but also get the optimal objective solution,which has a certain application value.