Comparative Study on Three Novel Hybrid Excited Multitooth Flux-switching Permanent Magnet Machines

In this paper, to apply the advantages of hybrid excited (HE) machine to flux switching permanent magnet machine with multi-tooth stator structure (MFSPM), three novel hybrid excited multitooth flux switching permanent magnet (HE-MFSPM) machines are proposed. The three topologies are basically the same except that PM with radial magnetization is added in each dummy slot in Model II, while a fault tolerant tooth is employed and wound with field winding in Model III. In order to have better flux regulation and lower demagnetization risk, parallel-hybrid-excited structure is adopted in all of the three machines. Then, to evaluate the electromagnetic performance and flux regulation capability of the three HE-MFSPM machines, a series of comparisons, such as flux linkage, back electromotive force (back-EMF), cogging torque, electromagnetic torque, torque ripple, overload capability and flux weakening capability, are conducted by finite element analysis (FEA). The predicted results show that all the proposed three HE-MFSPM machines exhibit good ability of flux regulation due to the addition of field windings. But Model III is superior to Model I and Model II since it exhibits most effective flux regulation capability, highest average torque on rated current density, best overload capability and widest speed range. Moreover, fault-tolerant ability and modularity exist in Model III because of the existence of fault-tolerant teeth.