ZHANG Guoping, WANG Fuqiang, ZHANG Hongfu, YUAN Guili
In the grid-connected control of multiphase permanent magnet synchronous motor (PMSM) flywheel energy storage systems, maintaining stable DC bus voltage and ensuring fast response of grid-side instantaneous active power are critical requirements. However, conventional control strategies often suffer from slow dynamic response and large steady-state deviations. To address these issues, this paper proposes a grid-connected control strategy for a high-speed flywheel energy storage system driven by a six-phase PMSM. Corresponding control methods are designed for the three sequential stages of the grid-connection process: flywheel acceleration, grid-connection preparation, and grid-connected operation.During the acceleration stage, the DC bus voltage is controlled by the grid-side converter, while the flywheel speed is regulated by the motor-side converter. In the preparation and operation stages, the motor-side converter maintains the DC bus voltage, and the grid-side converter controls the power delivered to the grid. Simulation results based on a six-phase PMSM mathematical model verify the effectiveness of the proposed strategy. The system achieves stable DC bus voltage during grid-connected operation and demonstrates faster power response compared to conventional methods. Under step changes in power commands of 100 kW, 200 kW, 300 kW, 400 kW, and 500 kW, the response time is reduced by 3 ms, 9 ms, 14 ms, 27 ms, and 53 ms.
