Design and control of a high torque density and high field-weakening performance permanent magnet vernier machine

The technology using the permanent-magnet vernier machine (PMVM) in electric vehicle (EV) to improve torque density and field-weakening performance is presented. The gap flux density analysis indicates that the torque is was produced both by fundamental and harmonic component of the field. Based on the analysis of the relationship investigations between the torque and structure parameters, the structure parameters are determined. The high torque/volume ratio and torque/mass ratio of the new design shows the high torque density characteristics of PMVM. The optimum current control strategy is presented for PMVM and compared with the sample permanent magnet synchronous machine (PMSM) in the end. The comparisons indicate that PMVM has well field-weakening ability while holding high torque density and is another good choice for the EV drive.