Performance analysis and design optimization of asymmetric interior permanent magnet synchronous machine for electric vehicles applications

A novel asymmetric delta-type and Spoke-type interior permanent magnet synchronous machine (ASD-IPM) is proposed for electric vehicles (EVs) application that uses the magnetic field shifting technique to maximise the average torque and lessen torque ripples. The proposed ASD-IPM is deduced from the conventional asymmetric spoke and V-shape IPM by attaching additional asymmetric flux barriers (AFB) to the left side of the spoke-type PMs and to the other side of the delta-type PMs. This configuration helps in reducing the leakage flux and achieving good flux concentration. The proposed design is optimised through a Genetic Algorithm (GA) to investigate the electromagnetic performances at no-load and on-load conditions. Also, the efficiency maps of both the proposed design and conventional design are analysed and compared. The results show that the proposed ASD-AIPM has superior efficiency and a favorable torque profile, making it a suitable choice for electric vehicle applications. Furthermore, the proposed design is rescaled to the Toyota Prius 2010 design, with the only change in the slot/pole pair combination due to the presence of spoke-PMs in the proposed design. The proposed ASD-IPM achieves 7% higher torque than the existing Toyota Prius 2010 model. The efficiency maps of the rescaled design are also analysed and compared.