Research On Electromagnetic Performance Of Multi-tooth Switched Flux Memory Machine Of Different Stator Structure

Multi-tooth switched flux memory machine(MSFMM)which combines the concepts of switched flux memory machine and multi-tooth switched flux permanent magnet machine has the excellent magnetic adjustment performance,wide speed range and high efficiency operation area,as well as the advantages of sinusoidal induction electromotive force,bipolar flux,small torque ripple and so on.The low coercive force(LCF)permanent magnet is used to excite the machine,and the magnetization state of LCF permanent magnet can be changed by applying a short-time current pulse to the stator excitation windings so as to adjust the air gap magnetic field with little excitation loss,which solves the problem of the difficulty in adjusting the air gap magnetic field of the traditional permanent magnet synchronous machine.As a stator hybrid permanent magnet memory machine,LCF permanent magnet,NdFeB permanent magnet,armature windings and excitation windings are all placed on the stator of MSFMM,and the stator teeth are multi-tooth structure.The rotor structure is the same as switched reluctance machine,which has high reliability and good heat dissipation performance.Therefore,the stator structure parameters have a great influence on the machine performance.By designing the stator structure of the machine,the E-core MSFMM is proposed based on the C-core MSFMM,and three E-core stator tooth structures are given.Combined with the finite element simulation and magnetic circuit model,the distribution of the internal magnetic field of the machine is analyzed,and the influence of the stator structure on the electromagnetic performance of the MSFMM is studied.Taking MSFMM as the research object,firstly,the topological structures of two kinds of MSFMM with different stator structure are proposed,the principle of switched flux is introduced,the magnetic circuit structure and working principle are analyzed,and the mathematical model of MSFMM is established.Secondly,the electromagnetic performance of two kinds of MSFMM with different stator structure,including flux,back EMF,dq-axis inductances,torque and efficiency are analyzed and compared by establishing the 2D finite element models of MSFMM.Through theoretical analysis,the design principles of the structural parameters of MSFMM are given,including the size of stator teeth,rotor poles and permanent magnets.Combined with the finite element simulation,the stator structure of MSFMM is optimized to improve the flux linkage and electromagnetic torque.Finally the basic principle of the magnetic circuit method is introduced,and the magnetic circuit model of MSFMM is established based on the magnetic circuit method.The analytical expression of electromagnetic parameters is derived,and the influence of stator structure on the electromagnetic performance of MSFMM is analyzed.The research results show that the proposed E-core MSFMM can improve the machine’s magnetic adjustment performance and electromagnetic torque.Compared with the C-core MSFMM,the magnetic adjustment performance is improved by 11.8%,and the maximum torque is increased by 7.7%.