A New Control Strategy for a Bidirectional qZSI as an Interlink Converter in a Hybrid AC/DC Microgrid

This paper presents a new control strategy for a bidirectional quasi-Z source inverter (qZSI) used as the interlink converter in hybrid AC/DC microgrids. The proposed strategy provides the maximum constant boost (MCB) for the qZSI in the islanded and gird-connected modes of microgrid operation. The MCB is also fulfilled for the transition of the microgrid between the two modes. Furthermore, as opposed to the conventional qZSIs, the proposed approach maintains the MCB without need to additional control loop for regulating the voltage of the capacitor at the DC side of the qZSI interlink. The efficiency of the proposed method to control the voltage of the DC and the AC subgrids is evaluated by applying it on a typical hybrid microgrid simulated in MATLAB/Simulink environment. It is shown that the proposed method properly works in the grid connected mode, islanded modes and the transition between them.