| Since the 19 th century,vehicles have become an important transportation tool for human beings.However,the consumption of fossil fuels and pollutant emission has become an important obstacle to human survival and development.Electric vehicles(EVs)which feature non-pollution,energy conservation,environment protection,and high energy efficiency,is becoming a new development direction in the field of the automobile.The outer-rotor permanent magnet flux switching(PMFS)motors have a wide application prospect in electric vehicle field due to the advantages of high efficiency,high torque density and simple rotor structure.The finite element analysis(FEA)method is a common method for the motor analysis.Although the accuracy of this method is high,the complexity computation and high time consuming restrict the application of the method in the rapid design and analysis of the motor.In addition,due to the phenomenon of the magnetic field saturation in the outer-rotor PMFS motor,the sophisticated relationship of the magnetic field,and other issues,the traditional magnetic circuit method and analytical method are no longer applicable,and the computation errors also cannot accept.Consequently,a varying-network magnetic circuit(VNMC)method is proposed in this paper.Based on the method,the electromagnetic performances and optimization of the outer-rotor PMFS motor are investigated.This method not only inherited the rapidity and simplicity of the traditional magnetic circuit method,but also improved the accuracy of the calculation results,and the design efficiency of the motor is also improved effectively.The main research contents of the paper are as follows:1.Research on the basic theory and modeling of the VNMC method.The magnetic circuit law in the VNMC was obtained through the analogy with the circuit theory,including Ampere circuital law,Ohm's law and Kirchhoff's law.Based on these magnetic circuit theories,combined with the structural characteristics of the outer-rotor PMFS motor,the equivalent permeance model is given for the stator androtor,armature windings,air-gap,and permanent magnet of the motor,and the equivalent permeability calculation formula is deduced,thus the VNMC model of the outer-rotor PMFS motor and the corresponding node permeability matrix are established.In order to improve the accuracy of the calculation,the VNMC model was modified.2.Computation model of the outer rotor PMFS motor.Based on the VC++software platform,the original and modified VNMC model of the outer-rotor PMFS motor are programmed.According to the flow chart of VNMC method,the equation of node permeability matrix is solved by using successive over relaxation(SOR)iteration method.And the electromagnetic properties of the flux,back-EMF and the electromagnetic mean torque of the outer-rotor PMFS motor under two models are respectively obtained by the aforementioned method.The results are compared with the finite element method to verify the validity and accuracy of the VNMC method.3.Multi-objective optimization design of the outer rotor PMFS motor based on the VNMC method combined with sensitivity analysis.On the basis of the application background and situation of the motor,the optimization target of the motor is determined,and the corresponding optimization model is established.The design parameters of the motor are stratified according to the sensitivity analysis method,and the design parameters of the different layer is optimized specially.The sequential nonlinear programming algorithm method is used to determine the optimal solution,the optimal structural parameters of the motor are obtained.The FEA method is employed to verify the rationality and accuracy of the VNMC method.4.Prototype manufacture and experimental platform establishment.The prototype is constructed,and the experiment platform is set up.The related experiments are done.The results are compared with that obtained by the VNMC and FEA method,and the results further verify the accuracy and effectiveness of the VNMC method. |
PDF Full Text Request