A Single-Current-Regulator Flux-Weakening Control for PMSM Under Square-Wave Mode With Wider Operation Range

In the rail transit traction system, the traction motor will operate under square-wave mode at high speed. The voltage amplitude will be fixed under the square-wave mode, while only the voltage angle can be regulated. The single-current-regulator (SCR) method is a good choice to regulate the voltage angle while keeping the voltage amplitude constant. However, the existing SCR methods cannot work stably in the whole flux-weakening area of the infinite speed system. The single
$d$
-axis current regulator-regulates
$q$
-axis voltage (SDCR-RQV) method that can provide a wider operation range is proposed in this article. SDCR-RQV is qualified for the permanent magnet synchronous motor (PMSM) used in rail transit, whether it is a finite speed system or an infinite speed system. The proposed method is analyzed in detail and verified by simulation and experimental results.