Research On The Hybrid Analytical Model For Fault-Tolerant Flux-Switching Permanent-Magnet Machine

As a type of stator permanent magnet machine,Fault-tolerant flux-switching permanent-magnet(FT-FSPM)machine has a simple rotor structure,and has the merits of high torque density and efficiency,excellent fault-tolerance,which has attracted many scholars’ attention in recent decades.The air gap magnetic field analysis of machine is the basis of all kinds of electromagnetic performance calculations.However,the fault-tolerant teeth and double salient structures make the modeling of FT-FSPM machine by using the finite element method more complicated.Consequently,this paper sets up the exact subdomain model of the FT-FSPM machine,which realizes the fast calculation of magnetic field distribution and electromagnetic performances.And a hybrid analytical model is proposed combining subdomain and equivalent magnetic circuits taking the influence of nonlinearity effect to electromagnetic performance into account.The hybrid model improves the calculation speed while maintaining high accuracy.The main research contents of this work include the following aspects:1.Research on the FT-FSPM machine is carried out.The structural characteristics and operating principle of machine are analyzed.The process of air-gap magnetic field modulation of stator and rotor salient pole structure is briefly described.The ratio of mutual-inductance and self-inductance of machine and the influence of shortcircuit current to back-EMF of adjacent phases under short circuit fault is employed to evaluate the fault tolerance performance.2.In the two-dimensional polar coordinate plane,the FT-FSPM machine is divided into sub-domains.The slot region and permanent-magnet region are equivalent to sector regions.The accurate subdomain model is established,the expressions of particular solution under different magnetization modes of the permanent magnet and different arrangements of windings are given,which lays a foundation for the further establishment of hybrid analytical model.3.The equivalent current sheets are introduced to modify the nonlinearity effect of material.The rotor and stator equivalent magnetic circuits are built,and the magnetic vector potential analytical expression in each region of the nonlinear subdomain is derived.The values of current densities used as the boundary conditions of subdomain model are obtained by the iteration of magnetic circuits,and the nonlinear hybrid analytical model of the FT-FSPM machine is established.4.On the basis of nonlinear hybrid analytical model,the improvements are developed to rotor equivalent magnetic circuit.The flux inputs in opposite directions of rotor teeth are calculated.Based on the principle of conservation of magnetomotive force,an iterative calculation is introduced to post-process magnetic flux density.The errors of radial magnetic flux density are eliminated.The nonlinearity effect is predicted more accurately.5.The experimental prototype of the FT-FSPM machine is manufactured.The relevant experimental platform is built.The unload back-EMF and output torque are tested.The correctness of the theoretical analysis and nonlinear hybrid analytical model are verified by comparing the simulation,analytical and experimental data.