Analysis And Design Of A Compound Flux-switching Permanent Magnet Machine For Extended Range Electric Vehicles

With the shortage of fossil energy and the increasingly serious environmental pollution,new energy vehicles have become the focus of attention in academic and industrial circles at home and abroad.Presently,the main types of new energy vehicles are pure electric vehicles,hybrid electric vehicles and extended-range electric vehicles.As a classification of hybrid electric vehicles,the fuel based extended range electric vehicles(FB-EREVs)own the advantages of long driving distance,high fuel saving rate and low reliance of charging piles.However,FB-EREVs adopt series power system which needs two machines,namely,generator and drive motor.Thus,the power system of FB-EREVs greatly occupies the available space of the vehicle,further more,the complexity and the processing difficulty of the power system have been increased.In order to solve this problem,a compound machine,which integrates generator and drive motor together,is proposed and named as compound flux-switching permanent magnet machine(CFSPM machine).CFSPM machine not only increases the integration of the power system of FB-EREVs,but also saves the internal space of vehicles,supplying a new route for the development of extender in EREVs.The main contents and innovations of this dissertation are as follows:1.The types as well as advantages and disadvantages of new energy vehicles at home and abroad are introduced.Power systems of FB-EREVs at home and abroad are analyzed and their defects are summarized.The research status and progress of dual-rotor machines are summarized.2.The structure and operation principle of CFSPM are introduced.Firstly,inner and outer machines structures of CFSPM machine are analyzed,and then the principle of air gap magnetic field regulation in CFSPM machine is studied and revealed,and the relationship between PMs field and armature reactive magnetic field and the mechanism of torque generation are clarified.The operation principle mode of CFSPM machine are introduced,including the generation principle of the inner machine while generating electricity and the electricmotion principle of the outer machine when operating electronically.3.The mathematical model of three-phase CFSPM machine is built.By analyzing the inductance coupling of armature windings of the inner and outer machines,the conditions for complete electromagnetic decoupling of inner and outer machines are proposed.Furthermore,the complex CFSPM machine model is simplified to two independent three-phase PM machines,which provides a theoretical basis for subsequent analysis and control.4.The phenomenon of magnetic field coupling between inner and outer machines of CFSPM machine is analyzed.Firstly,according to the relative position between inner and outer stator teeth,three kinds of stator teeth relations are defined,namely series teeth,parallel teeth and independent teeth.Secondly,according to the relative position of stator teeth of inner and outer machines,four representative machine structures are selected for analysis,and their different magnetic field coupling mechanisms are elaborated.Then a quantitative method of coupling degree is proposed,on this basis,the effect of armature magnetic field on the PM field couplings of inner and outer machines is studied,the results indicate that the armature reaction magnetic field can be neglected.Thirdly,the influence of PM field coupling on CFSPM machine performance is studied.Finally,the optimal combination of inner and outer stator teeth is clarified.5.The power distribution criterion for inner and outer machines of CFSPM machine is proposed.Firstly,the power dimension(PD)equations of inner and outer machines are derived respectively,on this basis,PD equation of whole CFSPM machine is given.Secondly,according to the geometry structure of CFSPM machine,the volume matching relationship between inner and outer machines is deduced,combined with the PD equation,the power distribution criteria of inner and outer machines are proposed.6.The optimization design method of CFSPM machine is proposed.Firstly,on the basis of armature windings complementarity,the criterions of optimum pole-slot matchings of inner and outer machines are proposed.Secondly,ten key dimension coefficients are defined and optimized,and the optimum design range of dimension parameters is given.7.A CFSPM machine prototype is manufactured and the experimental verification is completed.Cup-shaped outer rotor,L-type bracket,non-magnetic isolation ring opening assembly hole and inner and outer air-gaps re-processing are adopted to ensure the machining accuracy and installation reliability of CFSPM machine prototype.The power generation performance of the inner machine and the electricmotion performance of the outer machine are tested.Aslo,the experiment of PM field coupling between inner and outer machines is completed.