An Improved Power Supply Switching Method of Segmented Long Primary Linear Motors for High-Speed Applications

Segmented power supply of Linear motors (LMs) is usually adopted for the purpose of reducing converter capacity and improving efficiency. In high-speed occasions, thyristor-based switches are always employed to achieve power supply switching for segmented LMs. However, thyristor-based switches can only be turned off at the moment of current zero crossing point, leading to unbalanced operations and overcurrents of LMs during power supply switching duration. To address this issue, the current dynamic characteristics of the LM is analyzed, and the analytical expressions are also derived during the turning off process. Furthermore, an improved power supply switching method is proposed to complete fast switching and to avoid overcurrent. Finally, the correctness of the presented analysis and the effectiveness of the proposed method are both validated by simulation results.