A Novel Concept of Pseudo Harmonic Transmission Ratio in PM Vernier Motor for In-Wheel Traction Application

This paper proposes the novel concept titled as pseudo harmonic transmission ratio (PHTR) in permanent magnet vernier motor (PMVM) for in-wheel traction. The PHTR is equivalent to the mechanical gear in conventional transmission. Hence, the torque expressions of PMVM and PMSM plus mechanical gear are both derived and analyzed by theoretical analysis and FEA respectively. Moreover, the output capability of PMVM with same PHTR is compared with the PMSM plus mechanical reduction gear under the same in-wheel space. Meanwhile, in order to evaluate the harmonic discount degree comparing with the mechanical reduction gear, the harmonic transmission factor k_htf is introduced and defined in PMVM, which will contribute to further understanding the harmonic working principle. Finally, the results between theoretical analysis and FEA method match well, which exactly validates the accuracy of results.