Magneto-thermal Coupling Analysis And Optimization Design Of A Controllable Flux Leakage Motor Considering Driving Cycle

In recently years,the pure electric vehicles(PEVs)have been strongly supported and promoted by governments and automobile manufacturers in various countries,which is because of the advantages of high security and efficiency,energy-saving and friendly to environment.Flux controllable permanent magnet motors have been widely recognized and valued by experts in the field of PEVs due to the wide speed range,high efficiency,and high torque density.As a driving motor for PEVs,the heat caused by long-term operation and frequent flux control and mode switching during operation has a serious negative impact on the normal operation of the motor.It is a key and technical difficulties for the driving motors in PEVs that how to realize the reasonable magnetothermal design,check the heat of the motor under multiple operating conditions,and achieve effective thermal management.According to the requirements of EVs under multiple operating conditions,a controllable leakage flux V-shape permanent magnet(CLF-VPM)motor is researched from perspective of the magneto-thermal coupling mechanism and design,optimization in this paper.The main research content includes the following parts:First,the development situation of new energy electric vehicles is introduced and the research status of the PM motors with the wide-speed and the thermal management of driving motors.The topology of the CLF-VPM motor is analyzed,and the loss performance of the CLF-VPM motor is researched.In addition,the relationship between the motor temperature rise and loss performance is qualitatively discussed.Secondly,the fundamental principle of temperature field analysis is introduced in detail,and a three-dimensional temperature field simulation model of CLF-VPM motor is established.the mathematical model,solution domain and boundary conditions of which are given.In addition,in order to make the simulation results closer to the true value,the magnetic-thermal two-way coupling method is applied to construct the CLF-VPM motor temperature field analysis model.Then,the steady-state temperature field analysis of convergence is achieved by the repeated iterative update.Then,considering the requirements of driving motors under multiple operating conditions,a temperature-constrained layered multi-objective optimal design under multiple operating conditions for the CLF-VPM motor is proposed.The layered optimization design includes working condition layer,electromagnetic layer and temperature layer.In the working condition layer,by establishing a vehicle model,the features of the motors under the multiple operating conditions is analyzed and the equivalent operating point is selected.The optimization target and structural design variables are picked up.Meanwhile,the methods of sensitivity analysis is applied classify design variables.The design variables with high sensitivity and low sensitivity are optimized by different methods,the aim of which is to obtain the optimal solution set.In the temperature layer,based on the motor performance optimization solution set,the loss performance of the motors is analyzed.In addition,the structure parameters of the CLF-VPM motor is optimized by the iterate of the temperature field model.Finally,the prototype of CLF-VPM motor parameters with the optimal structure is manufactured and the corresponding experimental test platform is built.The no-load back EMF,steady-state torque current waveform,start-up performance,variable-speed variable load and other dynamic performance are tested.In addition,by the results of the temperature curve under variable speed and variable load,the rationality of the selected motor and the feasibility and effectiveness of the proposed optimization method are verified.