Design And Performance Study Of Halbach-array Split-pole Permanent-magnet Vernier Motor

Halbach-array permanent-magnet vernier motors have broad development prospect,which have the magnetic field self-shielding while achieving the high output torque in direct-drive applications such as electric vehicles and wind power generation.Based on the previous research about permanent-magnet motors,a new Halbach-array split-pole permanent-magnet vernier motor(HASP-PMVM)has been proposed in this paper.The main contents are as follows:Firstly,the development and research status of permanent-magnet motors,vernier motors and Halbach-array motors have been introduced,and the topology of the HASP-PMVM has been confirmed.The radial and tangential air-gap flux density of the rotor permanent magnets have been calculated before or after the magnetic field modulation.Combined to the theory of electromagnetics and electromechanical energy conversion,the principle of the HASP-PMVM magnetic field modulation has been derived,then being contrasted with the traditional vernier motor.The mathematical model of the HASP-PMVM electromagnetic theory has been established.Combined with the magnetic field modulation principle,a series of the HASP-PMVM electromagnetic theory has been derived in detail,providing theoretical basis for motor design.Secondly,aiming to the parameters of basic dimensions,pole-slot fit,stator-slot shape,permanent magnets and windings,the HASP-PMVM structure and magnetic circuit have been designed,analogous to the traditional vernier motor design theory.Based on magnetic field distribution,magnetic cloud map and no-load air-gap flux density,the rationality of the HASP-PMVM magnetic circuit design has been verified in main working harmonic and harmonic periods by the finite element analysis software.The electromagnetic and output performances of the HASP-PMVM have been calculated and compared using the finite element method and the analytical method.The theoretical feasibility and the finite element model correctness of the HASP-PMVM have been verified in the aspect of magnetic field,magnetic circuit,electromagnetic and output performance.The effects of the factors including magnetization angle,pole-pole thickness,air-gap length,permanent magnets thickness,stator-cogging ratio,radial magnetic circuit size and permanent magnets space size on the electromagnetic and output performance of the HASP-PMVM have been explored by control variable method.The value range of each factor has been confirmed on the premise of maintaining high output and low pulsation.Thirdly,in order to maximize output torque,minimize torque ripple and maximize air gap flux density,the HASP-PMVM parameters have been optimized by the orthogonal experiment method and the mathematical statistics,using the output torque,torque ripple and air-gap flux density as test indicators.The effects of level and degree of the pole-pole thickness,air-gap length,permanent magnets thickness,stator-cogging ratio and their interactions on the output torque,torque ripple and air-gap flux density of the HASP-PMVM have been confirmed by the “Range Method” and “F Test Method”.The electromagnetic performance,output performance and magnetic circuit distribution of the optimized motor and initial motor have been compared.For different arrangements and magnetization methods of permanent magnets,a variety of Halbach-array permanent-magnet vernier motors have been proposed.Combined with HASP-PMVM,the electromagnetic performance,output performance and magnetic circuit of each proposed motor have been compared.Finally,the HASP-PMVM transient three-phase inductance and the d-q axis inductance have been calculated under rated conditions.The loss composition of the HASP-PMVM has been analyzed under rated conditions,and the efficiency maps have been drawn.Another expression form of the HASP-PMVM electromagnetic power and electromagnetic torque has been derived by the space-time vector diagram,and the HASP-PMVM constant speed and variable speed operating conditions have been confirmed.The HASP-PMVM electromagnetic performance and output performance under constant speed and variable speed conditions have been discussed.