Design,Modeling And Analysis Of Novel Dual-armature Flux-switching Machine

Thanks to the substitution of permanent magnet(PM)for DC excitation winding,the PM machines exhibit higher torque density and efficiency compared to the electrically excited machines.Consequently,they are promising for industrial applications such as electrical vehicle,wind power generation and aerospace application.The flux-switching PM(FSPM)machine is a type of stator-PM machine whose PMs and armature winding are integrated on the stator.The rotor of the FSPM machine is simple and robust,thus it is suitable for high speed applications.However,the space conflict between PMs and armature winding limits the torque density improvement of FSPM machine.Moreover,the conventional FSPM machine only consists one set of armature winding,thus its fault-tolerant capability is relatively low.These deficiencies limit the application of conventional FSPM machine in aerospace.Therefore,this thesis proposes a novel dual-armature FSPM(DAFSPM)machine with high torque density and high fault-tolerant capability.The DAFSPM machine can be derived from the conventional FSPM machine plus a rotor armature winding in rotor slots,which has the characteristic of dual-armature structure with stator and rotor armature windings.The torque density and fault-tolerant capability are improved prominently in the DAFSPM machine,thus it is very suitable for aerospace application which requires high torque density and high fault-tolerant capability.In this thesis,the topology,operating principle,electromagnetic performances,mathematical model,winding configuration,stator pole/rotor tooth number combination,equivalent magnetic circuit model and parameter optimization of the DAFSPM machine are investigated in detail,which lays a foundation for the popularization and application of DAFSPM machine.The main research of this thesis are as follows:Firstly,the deficiencies of the existing FSPM machine research are summarized and a novel DAFSPM machine topology is proposed.Then,the operating principle and main electromagnetic performances of the DAFSPM machine are analyzed.Secondly,the mathematical model of the DAFSPM machine is built under stator and rotor reference frames,respectively,which lays a theoretical foundation for the performance analyses and design of control strategy.Since the phases of stator and rotor windings and the fundamental frequencies of stator and rotor flux linkages are different,two Park transformation matrix with different dimensions are proposed in this thesis to transform the variables under stator reference frame into rotor reference frame,and then the mathematical model under rotor reference frame is obtained.Based on the mathematical model,the contents of flux linkage,phase voltage and electromagnetic torque of the DAFSPM machine are analyzed.It shows that the phase flux linkage of the DAFSPM machine is composed of PM flux linkage,stator and rotor armature reaction flux linkage,and the flux linkage due to magnetic coupling between stator and rotor windings.The variation of stator and rotor armature currents affect both stator and rotor phase voltages,while the PM torque is the major content of electromagnetic torque in DAFSPM machine.Thirdly,the design rules of winding configuration and stator pole/rotor tooth number combination of DAFSPM machine are established,which provides a theoretical basis for the design of winding configuration and selection of stator pole/rotor tooth number.Since there exists complicated restriction between stator pole number,rotor tooth number,stator and rotor phase number,the selection of stator pole/rotor tooth number and phase number of DAFSPM machine is different from that of FSPM machine.Therefore,the connection of stator and rotor coils of DAFSPM machine and the design of phase windings are investigated in this thesis using coil-EMF vector diagrams,and then,the relationships between stator pole number,rotor tooth number,stator and rotor phase numbers are investigated.It shows that the numbers of stator and rotor phases must be co-prime,so are the numbers of spokes in stator and rotor coil-EMF vector diagrams.Based on the former analyses,the feasible combinations of stator pole/rotor tooth number and stator/rotor phase number are proposed,and the influence of the number of winding layers and stator pole/rotor tooth number combination on electromagnetic performances of the DAFSPM machine are analyzed in order to optimize the winding configuration and stator pole/rotor tooth number combinationFourthly,in order to provide a fast and high accuracy tool for performance analyses and parameter optimization of the DAFSPM machine,the equivalent magnetic circuit models of the DAFSPM machine are built.The features of the magnetic flux distributions from PM flux source,stator armature reaction flux source,and rotor armature reaction flux source are investigated at first.It shows that the magnetic flux distribution from the three magnetic flux sources are different,which means that single magnetic circuit structure can not model the magnetic field of the DAFSPM machine accurately.Therefore,two conventional equivalent magnetic circuit models are established,and then,a novel equivalent magnetic circuit model is proposed in this thesis,which calculate the PM flux,stator armature reaction flux and rotor armature reaction flux separately.The electromagnetic performances of the DAFSPM machine predicted by the equivalent magnetic circuit models are compared.It shows that the proposed novel equivalent magnetic circuit model exhibits higher accuracy compared with conventional equivalent magnetic circuit models,while its solution speed is much faster than finite-element model.Finally,the topology of the DAFSPM machine is further developed and the design parameters of different DAFSPM machine topologies are optimized,which provides a guidance for the design of the machine.Firstly,the E-shaped and C-shaped stator core DAFSPM machine topologies are proposed and their operating principles are analyzed.Then,the influence of design parameters on average torque of the DAFSPM machines are investigated and the main design parameters are optimized.Thereafter,the performances of the DAFSPM machines with different stator core shapes and stator pole/rotor tooth number combinations are analyzed and compared with their FSPM counterpart machines.Finally,two DAFSPM prototype machines are manufactured and tested to validate the finite-element analyses in this thesis.