Optimization Design And Research On Hybrid Excitation Double-stator Bearingless Switched Reluctance Motor

Bearingless switched reluctance motor(BSRM)combines the advantages of switched reluctance motor(SRM)and magnetic bearings,which can be applied in high-speed,high-power density,high-reliability applications,such as aerospace,flywheel energy storage,automotive industry and other fields.To solve the coupling problems between the torque winding and the suspension winding and improve the system suspension output capacity,a hybrid excitation double stator bearingless switched reluctance motor(Hybrid Excitation DSBSRM)is proposed.Firstly,the basic structure and operation principle of hybrid excitation DSBSRM are given.On the basis the established equivalent magnetic circuit model and mathematical model of the motor is derived in detail.Then magnetic circuit formulas can be deduced for solving the radial force and torque.Electromagnetic characteristics are the basis of design and optimization,therefore three-dimensional finite element analysis(3D FEA)of the motor was established and the electromagnetic characteristics of the motor were systematically studied,including magnetic field analysis,air gap magnetic density analysis,inductance analysis,torque analysis,iron loss analysis,suspension force analysis and eccentric characteristics analysis.Due to the complex topological structure of the motor and large number of parameters,the motor design has become one of the focuses and difficulties in the research.According to the performance requirements of hybrid excitation DSBSRM,the structural parameters and electromagnetic parameters of the motor are preliminarily designed.The proposed hybrid excitation DSBSRM has excellent decoupling between the torque and suspension systems,from which we start to design motor.The design of the suspension system is based on the equivalent magnetic circuit of the bias magnetic field and the control magnetic field.And the design of the torque system is based on the power equation to derive the body size formula.In order to obtain the optimal performance of the motor,it is necessary to optimize the design structural parameters.The motor structure is optimized by finite element analysis to improve power density and realize magnetic circuit decoupling.The paper studies the generation of the suspension force and the mutual inductance ratio under different excitation modes to optimize the excitation mode.The influence of structural parameters on the performance of the motor was studied by univariate analysis to obtain the key parameters.Finally,the genetic algorithm(GA)is studied by motor parameter optimization design in detail and the optimized results are compared with initial parameters to obtain the optimalstructural parameter combination.