Topology And Electromagnetic Characteristic Investigation Of Novel Doubly Salient Permanent Magnet Machine

With the development of economy and society,the environmental protection and sustainable development have attracted more and more attention globally.Thus,the application of motor drive system instead of traditional fuel drive system in electric vehicles,ship propulsion and other fields is gradually becoming a research hotspot.And many demands for the driving motor,which is the heart of motor drive system,have been proposed containing high torque density,high power density,high efficiency,high reliability,and wide constant power speed range,et al.With both permanent magnet(PM)and armature winding placed on the stator,the doubly salient permanent magnet machine(DSPMM)has the merits of convenient heat dissipation,simple rotor structure,high reliability,suitable for high speed operation,et al.Besides,the DSPMM has the advantages of high torque density,high power density,high efficiency,et al.Therefore,the DSPMM could be one good candidate for the driving motor of motor drive system and has broad application prospects in electric vehicles,ship propulsion,et al.Currently,the research of DSPMM is conducted mainly based on the traditional structure with unipolar flux linkage.Though several novel topologies have been proposed and analyzed to improve the torque density or constant power speed range of DSPMM,there are still some issues in the relevant investigations,such as: The study on the new topology is insufficient(For the current single-phase DSPMM,the torque density and starting torque are relatively low.For the current three-phase DSPMM,the flux linkages of coils or winding are unipolar and the torque density is relatively small);Lacking of investigation on the modeling method of air-gap magnetic field;The study on the air-gap magnetic field regulation theory of HEDSM is insufficient.Thus,based on the single-phase and three-phase DSPMM,this thesis has proposed several novel DSPMMs and HEDSMs with bipolar coil and winding flux linkage.Moreover,the sduties on the new topologies,air-gap magnetic field model(including simple equivalent magnetic circuit model and magnetomotive force-specific permeance model),design and analysis methods of electromagnetic performance(finite element algorithm and theoretical calculation),air-gap magnetic field regulation theory of HEDSM,et al.,are conducted comprehensively.The organization of this thesis is as follows.(1)Based on a DSPMM with bipolar winding flux linkage,the modeling method of analytical model of the air-gap magnetic field is investigated.Moreover,the winding function,no-load air-gap flux density,flux linkage,back electromagmotive force(EMF),et al.of the DSPMM are studied and analyzed comprehensively.A novel DSPMM is also proposed and analyzed to improve the power factor.(2)A novel single-phase DSPMM with asymmetric stator poles is proposed to improve the torque density and starting torque.Besides,the design and analysis methods of the proposed single-phase DSPMM are also investigated,including the derivation of dimensional equation,modeling and calculation of simple equivalent magnetic circuit,analytical calculation of current and torque,analysis method of starting performance,and so on.The topology,operation principle,dimensional equation,analytical model,et al.of the proposed machine are analyzed comprehensively firstly.Then,the pole shoe,step air gap,and auxiliary teeth are introduced to further improve its torque performance.Besides,the comparison of torque and starting performance of the traditional and proposed single-phase DSPMM is studied comprehensively.Finally,a prototype is designed and manufactured to validate the relevant analysis.(3)The air-gap magnetic field regulation theory and operation principle of HEDSM are investigated comprehensively based on a novel HEDSM with bipolar coil and winding flux linkage.Firstly,the magnetomotive force-specific permeance model is made,and the no-load air-gap flux density,flux linkage and back electromotive force(EMF)are analyzed in detail.Then,based on the simple equivalent magnetic circuit,flux linkage equation and phasor diagram,the influence of field winding on the no-load flux density,flux linkage,back EMF,power factor,and torque is studied comprehensively.Besides,the key design parameters affecting the constant power speed range of HEDSM are also investigated and given.The relevant research could be one good reference for the design and optimization of HEDSM.(4)The electromagnetic performance of the proposed HEDSM is studied comprehensively.Firstly,the comparison of key performance indexes of different topologies of the HEDSM is made.Then,the influence of main structure parameters,which includes stator split ratio,size of permanent magnet,stator and rotor pole width,stator pole angle,et al.on the no-load flux linkage,back EMF,cogging torque,average torque and flux regulation ability is investigated comprehensively.Besides,the effect of distribution coefficient of thermal load of armature and field winding on the no-load flux linkage,back EMF,cogging torque,average torque,power factor,flux regulation ability,constant power speed range,et al.is analyzed in detail.A full comparison of the proposed HEDSM and traditional machines is also carried out.Finally,one prototype of the novel 12/7 HEDSM is manufactured and tested to validate the relevant theoretical analysis.