Design And Research Of Outer-Rotor Flux-Switching Permanent Magnet Motors

With the rapid development of economy,the automobile productions and sales have been increasing year by year,which bring the convenience to our lives.However,they also have resulted in the environmental pollution and resource shortages.Therefore,the electric vehicles(EVs)have become the development trend in the automotive industry due to the advantages of energy saving and environmental protection.Among them,four-wheel drive(4WD)EVs have attracted increasing attention in automotive industrial applications because of the merits of high stability and comfort.As the key components in 4WD system of EVs,the in-wheel motors have become one of the emerging research orientations in automotive drive motor applications as they offers potential superior features of high efficiency,control flexibility.Being a member of permanent magnet brushless(PMBL)motors,the flux switching permanent magnet(FSPM)motor possesses the advantages of high power density,high efficiency,simple rotor,which has the potential application prospects in the in-wheel direct drive applications.By incorporating the concept of in-wheel motor into FSPM motor,two outer-rotor in-wheel FSPM motors with innovative structures are investigated deeply in this paper.The main research results are as follows:1.The basic structures of the two outer-rotor in-wheel FSPM motors are proposed,including I-shaped flux-switching permanent magnet(I-FSPM)motor and V-shaped flux-switching permanent magnet(V-FSPM)motor.Then,the basic operation principle of this type of motor is narrated.2.The general design method of the outer-rotor FSPM motor is established.In particular,the general relationship between the output torque,the stator slot area and the permanent magnet utilization is deduced,which provides the theoretical basis for designing the outer-rotor FSPM motor with high torque density.3.Considering the relative complicated structure and large numbers of design variables in outer-rotor FSPM motor,a multi-objective optimization strategy based on the sensitivity stratification of design variables is proposed in this paper.The design variables are devided into two levels and the two levels of design variables are respectively optimized with different methods,which realizes the comprehensive optimal solution between the multiple design goals of output torque,torque ripple and cogging torque;4.After determining the optimal values of two motors,the basic performances of two motors are compared in detail.To extensively evaluate the structural features of the two motors,the torque characteristics and permanent magnet usage efficiency are further analyzed and compared under the three different conditions,consisting of the same current density and winding filling factor,same copper loss,and same phase current.The effective conclusion of the V-FSPM with higher torque density and permanent magnet utilization is obtained.5.Two prototyped motors are manufactured and the corresponding experimental platforms are set up.The experimental results verify the accuracy of the theoretical analysis and the finite element simulation results,which provides the theoretical and experimental basis for the practical study of outer-rotor FSPM motor.