Grid current control strategy based on Z-source capacitor voltage change

Z-source inverter is a single-stage system. It has some advantages such as simple structure, high reliability of the inverter for avoiding influence of the shoot-through by EMI, and small output waveform distortion. Especially, this topology applies to the occasions of large rang input voltage such as PV power generation, etc. In PV grid-connected system, the frequent change of output current will bring the negative impact on the power quality. This paper proposes the Z-source capacitor voltage-change adjustment method to control ac line current amplitude, combined with the characteristics of single-phase Z-source PV grid-connected inverter. The proposed method can improve the power quality of the grid and minimize the injected ac line current variation. The experimental results verify the validity of the proposed control strategy.