Capacitor Voltage Round-robin Transmission Modes for MMC Distributed Control Systems

Most MMC distributed control systems require the central controller to collect capacitor voltages measured by local controllers to perform the phase average capacitor voltage control. Transmitting considerable capacitor voltages can greatly increase the communication burden in an MMC with numerous submodules. In this letter, we aim to significantly reduce the communication burden with adequate data exchange to maintain the control performance by proposing two round-robin transmission modes with voltage-ripple-filtering capability. The two transmission modes are elaborately designed to filter out specific harmonics for the removal of the low-pass filter in the voltage control loop. The feasibility of the capacitor voltage transmission modes is confirmed by the simulation and experimental results.