A Novel Method to Reduce of Cogging Force in a Linear Flux-Switching Permanent Magnet Brushless AC Machine

The primary linear flux-switching permanent magnet (LFSPM) motor has the merits of high speed, high response, and direct drive. However, the presence of the cogging force in LFSPM motors compromises position and speed control accuracy, which can be particularly troublesome at low speeds. A novel approach of suppressing the slot effect cogging force for LFSPM is proposed according to repetitive control of time-varying periodic signals. The time-varying periodic thrust disturbance in t-domain is transformed to the signals defined in the x-domain, and a repetitive controller is designed. Furthermore, a series of specific harmonic currents are added into q-axis reference current, resulting in additional force components to counteract the end effect cogging force. Finally, experimental evaluations of the control strategy are performed on an AD5435-controlled LFSPM drive platform. The simulations and experiments verify that the proposed method can suppress the thrust ripple effectively.