Design And Analysis Of Pole-Changing Modular Rotor-Permanent-Magnet Flux-Switching Motor

Electric tractors have attracted extensive attention from governments and agricultural equipment manufacturers all over the world because of its advantages of less pollution,high energy efficiency and convenient operation,.In view of the requirements of electric tractors on the torque density,speed range and operating efficiency in full speed range,this paper proposes a 24-slot 11/22 pair poles polechanging rotor permanent-magnet flux-switching motor(PC-RPMFS).According to the requirements of pole-changing operation,two kinds of pole-pair permanent magnetic fields are generated by designing the rotor topology reasonably.Two working modes of the motor are finally formed by changing the connection form of armature winding,.On the basis of inheriting the high torque density of permanent magnet motor,the speed regulation range and full speed domain operation efficiency of the motor are effectively improved.In this thesis,the topological structure,operation principle,polechanging speed regulation principle,parameter design and electromagnetic performance analysis of PC-RPMFS motor are studied in detail.The main contents of this thesis are as follows:Firstly,the research status of pole-changing motor and flux-switching motor is reviewed.According to the requirements of pole-changing operation,the topological structure and operation principle of PC-RPMFS motor are discussed.The magnetomotive force-permeability model is established by equivalent magnetic circuit method,and the air gap magnetic density of the motor is analyzed.The speed regulation ability of the motor is discussed by using the limit circle of voltage and current,and the feasibility of changing pole and expanding speed of PC-RPMFS motor is verified theoretically.By comparing the results of finite element simulation and analysis calculation,the accuracy of calculation is proved.Secondly,the design method of PC-RPMFS motor is proposed.in the first place,the slot pole ratio of the motor is determined based on winding factor and positioning torque.Then the influence of main parameters on the motor performance is analyzed by finite element analysis.Take the torque maximization of mode I as the goal,the final design parameters of PC-RPMFS motor are obtained by comprehensively considerging the factors such as torque ripple and saturation of stator and rotor core,.Thirdly,the electromagnetic parameters of the motor in different operating modes are calculated and analyzed,including no-load flux linkage,cogging torque,torque,loss and efficiency,which verifies the rationality of the motor design.Finally,a PC-RPMFS prototype is manufactured and tested,by which the accuracy of theory and simulation is verified based on the comparison among the test results and theoretical analysis and simulation results.