Design And Analysis Of Novel Magnet-Axis-Shifting Interior Permanent Magnet Machine For Electric Vehicle Application

High torque/power density,high efficiency using minimum PM are the requirements for electric vehicle(EV)application.Interior Permanent Magnet(IPM)machines are regarded as the best choices for EV applications.However,symmetrical structures of the conventional machines generally suffer from a compromised utilization rate of the torque componentsmagnet torque(MT)and reluctance torque(RT),since they reach the peak values at different current angles.An asymmetric configuration of the rotor in the IPM machine can shift either one of the d-axes of the MT or RT,which reduces the current angle difference of the torque components resulting in better utilization rates.Reviewing the state-of-art of symmetrical and asymmetrical IPM machines,a novel magnet-axis-shifting IPM(MAS-IPM)machine is proposed for traction applications in this thesis.By asymmetrical PM distribution and adjustment of barriers width of the rotor,MAS effect can be achieved to make the two torque components reach their peaks at closer current angles.Compared with the benchmark Toyota Prius 2010 IPM machine,the proposed MASIPM machine can provide higher torque density and higher efficiency using same volume of PMs,which makes the novel machines become promising for EV application.The main works include several aspects,which can be summarized as follows:(1)The research background,significance and the recent developments of symmetrical and asymmetrical IPM machines are reviewed.The research significance of this thesis is stated.(2)Two asymmetric IPM machine topologies are designed and compared with respect to the achievements of the MAS effect and the output torque to select a promising candidate.(3)Based on Prius 2010 IPM machine,a novel MAS-IPM machine of the same dimensions is designed and optimized.(4)To verify the utility of the proposed design,the electromagnetic characteristics of Prius 2010 IPM and novel MAS-IPM machines are compared and analyzed to illuminate the MAS-IPM machines’ prospect for EV applications.