Research And Implementation Of A New Parallel Hybrid Excitation Machine Constituted By PMSM And Variable Reluctance Machine

Hybrid excitation machine (HEM) is beneficial tobroadening the speed rangeand overcoming thedifficulty of de-excitation at faultunder generating operationfor permanent-magnet (PM) machine, andreduces the dosage of rare earth permanent magnets. Parallel hybrid excitation machines, which are animportant branch in the research area of HEM, havea strong field adjusting capacity and reduce the riskof demagnetizationfor PM.In this paper, the traditional concept that thesame kind of machines withdifferent excitation source constitute the parallel hybrid excitation machine and then the basic issue oforganic combination of two different brushless mahine are investigatedto form a new hybrid excitationmachine.The high efficiency and high power density of permanent magnet synchronous machine(PMSM) are given full play, which is as same as the economic, reliable structure and strongfieldregulation ofelectro-magneticdoubly salient machine (DSEM).Firstly, hybrid excitation machinesare classified and summarizedsystematically from theperspective of magnetic circuit. The distinctionbetween the parallel-connection magnetic potential typeand parallel magnetic circuit type is indicated specially. The research status and development directionof parallel hybrid excitation machineare summarizeddetailedly.The principle and characteristics ofconcentrated winding PM machine andvariable reluctance machine are discussed. According to theprinciple of parallel type hybrid excitation, the basic constraints thatPMSM and variable reluctancemachineare integrated into aparallel hybrid excitation machine are studied, including the considerationand design criteria of slot/pole number, rotor pole-width of DESM, and windings configuration.etc. Thecore length ratio of the electric excitation partto the PM excitation partis analyzedunder different speedrequirements.The other scheme that PMSMis combined with the electric excitation flux-switchingmachine or other electrical excitation reluctance machines to constitute parallel hybrid excitationmachine are given. The field of the electric excitation partand the PM excitation part are studyed andoptimizedrespectively by two-dimensional finite element method (FEA) to get the electromagnetic andoutput characteristics, which lays the foundation for efficient and reasonable combination of twoparts.And then the field regulation capability is analyzed by three-dimensional FEA.A prototypeofpermanent magnet synchronous/doubly salient parallel hybrid excitation machine is developed. Theloadless and load experiments are completed.The experimental results show that the bidirectionalfield-regulating capabilityfacilitates wide field regulating range of6.5:1and de-excitation at fault ofinternal short-circuit. More, under loading conditions, due to thesalient effectof doubly salientmachine,the field regulating range will further increase. The output power of parallel hybrid excitation machine is the sum of the PM excitationand electrical excitation part. The reasonable structure andexcellent propertiesof parallel hybrid excitation machineare verified, which willlay the technicalfoundation of achieving a new type of brushless starter/generator.