Enhanced Dynamic Voltage Balance Control of Modular Multilevel Matrix Converters with Switched Circulating Current Control

This paper proposes an enhanced dynamic voltage balance control strategy for a modular multilevel matrix converter (M3C) that alternately injects two types of circulating currents. The strategy, referred as switched circulating current control (SCCC), injects single-frequency circulating current (SFCC) to reduce the capacitor voltage fluctuation during transients, and then switches to dual-frequency circulating current (DFCC) to improve the harmonic performance during steady-state. As a result, fluctuations in the capacitor voltage are effectively reduced using the SCCC strategy when compared to solely using the DFCC injection approach. Meanwhile, current harmonics during steady-state are also substantially reduced when compared to the SFCC injection method. Simulation investigations in Matlab/Simulink demonstrate the performance and effectiveness of the proposed control strategy.