Basic Research On Novel Magnet-Axis-Shifted Interior Permanent Magnet Machine

The traditional interior permanent magnet(IPM)machines employ symmetrical rotor structure,which normally suffer from compromised utilization rates of magnet torque and reluctance torque due to their different optimal current angles.A new IPM machine,which usually employs asymmetrical rotor structure such as additional slot design,is proposed for improving torque capability.The asymmetrical rotor IPM machine can make the reluctance axis shift towards the magnet axis to make magnet torque and reluctance torque reach their peak values at nearly identical current angles,which can be called as “reluctance-axis-shifted(RAS)effect”.However,the magnet axis and reluctance axis of RAS IPM machine change simultaneously due to the asymmetric additional slot design,which leads to relatively sophisticated design effort and complicated structure.Based on the review on the state-of-art of symmetrical and asymmetric IPM machines,a novel magnet-axis-shifted IPM(MAS-IPM)machine is proposed.This type of machine achieves the MAS effect by using asymmetrical magnet arrangement to make the two torque components share approximately same optimal current angles.According to permanent magnet location,this thesis proposes two novel MAS-IPM machine topologies.Compared with traditional IPM machines,the proposed MAS-IPM machines can provide higher torque density with the same magnet volume,which makes the novel machines become promising for electric vehicle(EV)applicationsThis thesis establishes basic studies on the proposed MAS-IPM machines in terms of their basic principle,design optimization,electromagnetic characteristics,experimental validation and possible applications for EV.The main works include several aspects,which can be summarized as follows:(1)The recent developments of symmetrical and asymmetrical IPM machines are reviewed,based on which the advantages and the disadvantages of different machines are introduced,and the research significance of this thesis is stated.(2)Two novel topologies of MAS-IPM machines are proposed.The basic principle of the MAS effect is illustrated.In addition,the asymmetry of air-gap flux densities is studied.(3)Based on finite element software JMAG 16,the initial MAS-IPM machine models are designed and built.Besides,the optimization procedures of the two rotors are presented in order to optimize the torque capability.(4)The electromagnetic characteristics of the MAS-IPM machines are investigated and compared with those of the corresponding traditional IPM machines.(5)The experimental results of two manufactured MAS-IPM machine prototypes are obtained by establishing the platform,and the simulation and experimental results are compared to verify the feasibility of the MAS-IPM machine designs(6)Based on A novel MAS-IPM machine with the same dimensions of the Prius 2010 IPM machine is designed.The the electromagnetic characteristics comparison between the two machines are presented to confirm the feasibility of the proposed MAS-IPM machine for electric vehicle applications.