Wide Frequency Range Control Strategy of Modular Multilevel Matrix Converter based on FCS-MPC

The modular multilevel matrix converter (M3C) can realize direct AC-AC operation, which could be applied in the fields of urban power grids as the core equipment of frequency conversion stations. However, if its input port frequency is close to or equal to the output frequency, the sub-module (SM) capacitor voltage will have a large low-frequency oscillation or even be out of balance. Therefore, the wide range frequency control strategy based on finite-control-set model predictive control (FCS-MPC) is proposed in this paper. Vector control injects circulating current, and the FCS-MPC tracks the current reference value and stabilizes the capacitor voltage in each branch. The proposed strategy can realize the energy balance of SMs and the stable power transmission under different conversion frequency ratios. The feasibility of the proposed strategy is validated through simulation results in MATLAB/Simulink.