A Novel Capacitor Voltage Control Strategy of MMC Applied for Permanent Magnet Synchronous Motor Drive

In order to improve the control performance of permanent magnet synchronous motor (PMSM) drive based on modular multilevel converter (MMC), a novel capacitor voltage control strategy of MMC applied for PMSM drive was proposed in this paper. With which the capacitor voltage of a sub-module was controlled to high or low flexibly according to the motor speed, and a mathematical analysis model of the flexible control strategy was also developed. Compared with the capacitor voltage stability of the traditional control, the control dimension of the novel control strategy was increased. With the proposed control strategy, the efficiency and precision of the output of the converter could be improved significantly. A laboratory prototype of a five-level MMC-based PMSM drive was built and experiments were carried out. The validity of the control strategy under steady and dynamic states was verified.