System Control Strategy of an MMC-Based PMSG Rectifier for Ship MVDC Integrated Power System

Integrated power system (IPS) technology is a revolution for ship power platform. To provide a medium-voltage dc (MVDC) source for the ship IPS, an MMC-based PWM rectifier for permanent magnetic synchronous generator (PMSG) is presented in this paper. The capacitor voltage fluctuation of MMC is modelled in this paper and the required capacitance in PMSG PWM rectifier is derived. The result indicates that although the MMC features the capacitor low-frequency fluctuation problem when driving a motor, it is suitable for high-speed motor drive applications. The higher the fundamental frequency, the smaller the voltage ripples. The system control strategy is also discussed, including the optimal flux-weakening control of PMSG and the voltage balance control of MMC. The proposed control strategy is demonstrated by the simulation on a 10kVDC MMC-based PMSG rectifier.