A Subsection Flux Weakening Scheme Based on Direct Traction Control for Long Primary Permanent Magnet Linear Synchronous Motor

The long primary permanent magnet linear synchronous motor (PMLSM) used for high speed maglev train needs to adopt flux weakening (FW) control to increase its speed due to the limitation of the traction inverter output voltage. In this paper, a subsection FW scheme in the linear modulation region based on the direct traction control (DTC) is proposed. By controlling the reference primary flux directly in different working states, the target speed is achieved faster compared with SFOC-FW control, and the demagnetization current is saved. The primary flux and traction fluctuation are reduced in the low speed working condition by leading the space vector modulation (SVM) algorithm into the proposed DTC-FW scheme. The simulation analysis is carried out and the effectiveness of the proposed scheme is verified.