A capacitance minimization control strategy for single-phase PV quasi-Z-source inverter

In single-phase photovoltaic (PV) system, there is double-frequency power mismatch existed between the dc input and ac output. The double-frequency ripple power needs to be buffered by passive network. In a conventional PV system, electrolytic capacitor is usually used for this purpose due to its high capacitance. However, electrolytic capacitor is considered to be one of the most failure prone components in a PV inverter. In this paper, a capacitance minimization control strategy is proposed to buffer the double-frequency ripple energy in single-phase Z-source /quasi-Z-source inverter application. Consequently, highly reliable film capacitor can be used. Without using any extra hardware components, the proposed control strategy can minimize the capacitance requirement and achieve low input voltage double-frequency ripple. A 1kW quasi-Z-source PV inverter using GaN devices is built in the lab. Simulation and experimental results are provided to verify the effectiveness of the proposed method.