A Novel Submodule Voltage Balancing Control Strategy for iM²DCT in MVDC Distribution Network

The iM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>DCT features high scalability and modularity, making it a key component in DC distribution networks. A critical challenge in controlling the iM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>DCT is balancing the submodule (SM) capacitor voltages. However, the traditional methods cannot effectively balance the SMs’ voltage under non-unity voltage conversion ratio scenarios. To facilitate the iM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> DCT’s operation range with balanced SMs’ voltage, this paper proposes a novel SM capacitor voltage balancing strategy by assigning the group signal pulses with the negative charge value in the descending order of SM voltage, followed by the distribution of phase-shift pulses with the positive charge value. The effectiveness and feasibility of this strategy are verified using a full-power MATLAB/Simulink model.