Analytical Model Research Of A Novel Double-layer Winding Ironless Permanent Magnet Linear Synchronous Motor

Because the ironless permanent magnet linear synchronous motor(ILPMLSM)with non-overlapping windings has simple structure,low thrust ripple and fast response,it is widely used in precise applications such as semiconductor processing device,machine center and so on.But the disadvantage of low thrust density is also obvious.The novel asymmetrical double-layer winding ILPMLSM(DW-ILPMLSM)with quasi-Halbach magnets can not only increase the thrust density,but also maintain the advantage of its simple structure.The research is focus on a 9s/6p DW-ILPMLSM.Firstly,the winding designing method,working principle and mathematical model of DW-ILPMLSM are introduced.However,the double-layer windings of the 9s/6p DW-ILPMLSM studied are asymmetric and the two ends of the primary are not closed,resulting in non-periodic armature current.To analyze this asymmetrical and aperiodic structure,and investigate its influences on electromagnetic characteristics,an improved twodimensional(2-D)analytical model is proposed.The model solves the no-load magnetic field based on the traditional subdomain method and equivalent magnetizing current method.Besides,the research introduces “virtual periodic primary” and solves the magnetic field of each winding layer to obtain armature reaction field.Based on the proposed analytical model,the back-EMF,electromagnetic thrust,normal force and inductance parameters are deduced finally.And the source of thrust ripple/ normal force ripple and the influences of asymmetrical inductances are analyzed in detail.By the results of Finite Element(FE)and experiments,the proposed analytical model is verified eventually.Moreover,the analytical model requires less computation time,which is helpful for optimizing the design of DW-ILPMLSM faster.