Study On Flux Adjustment Capability And Efficiency Of Novel Multi-tooth Switched Flux Permanent Magnet Memory Machine

The conventional permanent magnet synchronous machines are widely used due to the small size,light weight,high efficiency and high torque density.However,the conventional permanent magnet application synchronous machines reduce the operation efficiency and increase the risk of irreversible demagnetization in flux weakening region.The memory machines use low coercive force permanent magnet to adjust the flux,which really achieve the flux adjustment.When the air-gap flux density are changed,the magnetization level and direction of low coercive permanent magnet are changed by current pulses in memory machines,in which the copper loss is negligible.The flux adjustment method of memory machine widens the speed range of the machines and improves the operation efficiency in flux weakening region,which has broad prospects in industrial applications.Based on the review on the state-of-art of memory machines,this paper proposes a novel multi-tooth switched flux permanent magnet memory(MSFPMM)machine by combining the switched flux permanent magnet memory(SFPMM)machines and multi-teeth switched flux permanent magnet(MSFPM)machines,which not only inherit the advantages of MSFPM machine with high torque density,but also has the advantages of memory machines with flexible magnetization adjustment capability.Furthermore,this thesis presents the study on the MSFPMM machine in terms of structure,operation principle,electromagnetic characteristics,flux adjustable capability as well as efficiency.The main work of this paper includes the following aspects:Firstly,the recent development of the memory machines is introduced.The existing memory machines are reviewed including the machines topology and operation principle.Then,the applications of the memory machines are discussed.Based on the MSFPM machines,the novel MSFPMM machine is proposed.Furthermore,the structure,the combination of stator and rotor and the operation principle of the novel permanent magnet memory machine are analyzed.Meanwhile,the simplified magnetic circuit models of novel machine with different magnetization states of low coercive force permanent magnet are established.Secondly,the performance of the novel MSFPMM machine is calculated by the two-dimensional finite element analysis.In the machine,the electromagnetic characteristics with PM flux enhanced,weakened and low coercive magnet non-magnetized such as air-gap flux density,back-EMF and torque-speed characteristics,are presented.Furthermore,the flux weakening factors of the novel machine under different magnetization states are calculated,in which the flux weakening performance of the machine is analyzed.Meanwhile,the efficiency of the proposed machine with different magnetizations is calculated.Finally,the electromagnetic characteristics of MSFPMM machine and conventional SFPMM machine are compared.Then,the influence of small tooth and low coercive force permanent magnet on flux adjustment is studied.Meanwhile,the comparison of the MSFPMM machine and the conventional MSFPM machine is also researched,in which the efficiency improvement of the novel permanent magnet memory machine is presented.In addition,a prototype MSFPMM machine was built to verify the machine performanceIn this paper,a novel MSFPMM machine is proposed.Meanwhile,the flux adjustment capability and efficiency improvement of MSFPMM machine are investigated,which helps to the design of high efficiency memory machine.