Modeling and Current Control Method for LVPMM including Longitudinal End Effects

Compared with the conventional rotary motor, linear vernier permanent magnet machines (LVPMM) break at both ends, leading to three-phase asymmetry. The electromagnetic thrust ripple caused by the so-called longitudinal end effects worsens the precision of servo system. This paper focus on the elimination of the electromagnetic thrust ripple caused by the special structure of the LVPMM. Taking longitudinal end effects into consideration, the mathematical model of the LVPMM is deduced. To suppress the thrust force ripple and improve the current control performance, d-q axes current commands given method and decoupling algorithm is analyzed. The bode diagram of the proposed method is compared with the conventional method and shows its superiority. Joint simulation results of MATLAB/Simulink and ANSYS and experimental results are presented. It verifies that the proposed current control strategy reduces electromagnetic thrust ripple and improves the current control performance.