Low-stiffness comfort shift characteristics of a permanent magnet two-speed transmission for low-speed EV

Abstract

Jerk during shift in mechanical two-speed transmissions often have a serious impact on driving comfort. Within this paper, a proposed two-speed permanent magnet transmission is presented for low-speed electric vehicles, which utilizes magnetic non-contact transmission. This transmission is composed of a magnetic drive mechanism, a clutch, and a selectable one-way clutch. Then, a mathematical model is established for the magnetic-machine composite transmission based on the principles of magnetic field modulation and the concentrated parameter method. Additionally, a shift method that operates without power interruption is presented. Finally, the process of shifting is simulated for permanent magnet drive systems with varying magnetic coupling stiffness in a MATLAB/Simulink environment. The resulting torque calculations are compared with those obtained from the commercial software Maxwell. Simulation results indicate that the two-speed permanent magnet transmission does not experience power interruption during upshifting. Less jerk when shifting gears. Low magnetic coupling stiffness can reduce high-frequency vibration and enhance shift comfort. The findings from the torque calculations obtained through the proposed model align with those obtained from the commercial software Maxwell.