Research On Novel Dual-armature Switched Flux Permanent Magnet Linear Machines

Linear machines can realize the conversion between electric energy and linear motion mechanical energy in the absence of mechanical transmissions.Therefore,linear machines have become more and more popular in the fields of linear motion,such as high-grade CNC machine tools,semiconductor processing devices,electromagnetic launch systems,etc.However,with the ever-increasing demands of applications,the thrust force density of linear machine should be further improved.Based on the existing research works of secondary permanent magnet(PM)linear machines and primary PM linear machines,this thesis combines the topologies of these two kinds of machines,and innovatively proposes a kind of dual-armature switched flux PM linear machines(DASFPMLMs).Then,the machine topologies,operation principles,mathematical models,and electromagnetic performances are analyzed in depth.The superiority of DASFPMLMs in performance is investigated,while the results of analysis are validated by a prototype machine and experiments,which lay a foundation for the further research and application of DASFPMLMs.The detailed research works of this thesis are as follows:1.The advantages of linear machines in linear motion systems are introduced,and the corresponding applications are identified.Then,for the research hot spots in recent years,i.e.,primary PM linear machines,the research status of such machines is comprehensively summarized,and the topologies of these machines are compared.2.By adding another set of armature winding on the secondary of conventional switched flux PM linear machines,a kind of DASFPMLMs are proposed.The operation principle and mechanism of thrust force production are analyzed from the perspectives of coil flux-linkage and air-gap field.During the analysis of air-gap field,the spatial harmonics of air-gap flux density are derived through a simplified magnetomotive force-permeance model,and the effective harmonics which may produce average thrust force are investigated.After that,the contribution of each harmonic to average thrust force is calculated by the finite element method.3.By deriving the equations of flux linkage,voltage,power,thrust force,and mechanical motion,the mathematical models of DASFPMLMs are built under both static coordinate and synchronous motion coordinate.Then,the influence of mutual-inductance between primary and secondary armature windings is investigated,while the thrust force equation is validated by the finite element method.4.The electromagnetic performances of DASFPMLMs with different primary iron core structures are compared.Then,for the DASFPMLM having the optimal primary iron core structure,its primary/secondary pole number combinations are investigated.By theoretically analyzing the machine detent forces,winding arrangements,inverter topologies,and numbers of power electronic devices under different pole number combinations,several pole number combinations potentially having better performances are selected.Afterwards,the corresponding machine performances of those pole number combinations are analyzed.5.Based on the aforementioned research works,the DASFPMLM with the optimal primary iron core structure and pole number combination is selected.The performances of that DASFPMLM and a conventional surface-mounted PM linear machine are compared from the perspectives of electromagnetic and thermal characteristics.It is found that under the same limitation of temperature rise,the DASFPMLM can exhibit higher thrust force density than the surface-mounted PM linear machine.Meanwhile,a DASFPMLM prototype is manufactured and the corresponding test rig is established.The theoretical analysis and predicted results of finite element method are validated through the performance test of the prototype machine.