Design And Analysis Of Hybrid Permanet Magnet Axial Field Flux-switching Memory Machine

Memory machine is a new type of variable flux permanent magnet(PM)machine.This type of machine directly adjusts the magnetization state of the PM by the short-time pulse mag-netic field to realize continuous adjustment of the air-gap magnetic field.The merits are fast responding speed,wide regulation range,continuous regulation and extremely low energy con-sumption.Therefore,it has broad application prospects in the field of adjustable speed drives.According to the amount of PMs used,memory machines can be divided into two categories:single PM memory machine and hybrid PM memory machine.Existing research shows that al-though the former has a an extremely wide flux regulation range,it also faces many bottlenecks such as low power density and easy demagnetization of PMs.Therefore,using hybrid PMs to improve the performance of PM memory machine has become the focus of current research.In this dissertation,a series PM axial field flux-switching memory(SPM-AFFSM)ma-chine is studied.The characteristic modeling of low coercive force PM in hybrid PM and the memory flux regulation mechanism due the magnetizaiton state variation is investigated.The general analysis and design method of hybrid PM memory machine is proposed.The ma-chine topology,electromagnetic characteristics and flux regulation characteristics are deeply analyzed,which lays a certain theoretical and technical foundation for the application of hybrid PM memory machines in the field of adjustable speed drives.The main research works of this dissertation are summarized as follows:1.The research background and significance of the subject are introduced.The research status of PM memory machine at home and abroad,including different types of memory ma-chines,their topological structure and machine analysis and design methods,are analysed and summaried.2.A mesh-based equivalent magnetic circuit method considering the hysteresis character-istics of PM is proposed on the basis of the existing research.The hysteresis model of AlNiCo is established based on the classical Preisach hysteresis model.Then,the hysteresis model is coupled with the lumped parameter magnetic equivalent circuit model and a mesh-based mag-netic equivalent circuit model respectively to obtain the work trajectory of low coercive PM during the process of flux regulation.The working mechanism of the hybrid PM is studied.The flux regulation capability and anti-demagnetization capability of PMs with different hybrid PM topologies are compared and analyzed.Based on the analysis results,the basic rules of hybrid PM parameter design are given,which lays a foundation for subsequent analysis.3.Based on the analysis of the topology and working principle of hybrid PM axial field flux switching machine.The topology of SPM-AFFSM machine with additional magnetization winding is proposed.The power-size equation of the SPM-AFFSM machine is derived.The general design method of SPM-AFFSM machine is proposed.4.The hybrid PM is the key factor for the memory flux regulation.Based on the above-mentioned mesh-based equivalent magnetic circuit model that takes hysteresis into account is used to build the magnetic circuit model of SPM-AFFSM machine for the first time.The node magnetic potential matrix is derived.The magnetic hysteresis characteristics are processed by the fixed-point technique,and the nonlinear magnetic circuit equation is solved by the Newton-Raphson method.The influence of the parameters of PMs on the flux regulation performance is studied.The method reduces the complexity of magnetic circuit modeling and improves the design efficiency of the PMs in SPM-AFFSM machine.5.Based on the 3D finite element method(FEM),the electromagnetic properties of the SPM-AFFSM machine under different magnetization states are studied.The unique hysteresis magnetic characteristics of the memory machine are explored,which enriches the connotation of the magnetic modulation characteristics of the memory machine.By switching the magneti-zation winding to the hybrid excitation winding to achieve hybrid excitation,the flux regulation range of the memory machine can be further broaden.6.Based on the above research,a prototype of SPM-AFFSM machine is manufactured,and the magnetization control hardware and experimental platform were built.The static and dynamic flux regulation characteristics,hybrid excitation characteristics and electromagnetic performance of the prototype were tested to verify feasibility of the proposed design method.