PROJECT TITLE :

A Single-Phase PV Quasi-Z-Source Inverter With Reduced Capacitance Using Modified Modulation and Double-Frequency Ripple Suppression Control

ABSTRACT:

In single-section photovoltaic (PV) system, there is double-frequency power mismatch existed between the dc input and ac output. The double-frequency ripple (DFR) energy desires to be buffered by passive network. Otherwise, the ripple energy will flow into the input side and adversely affect the PV energy harvest. During a conventional PV system, electrolytic capacitors are usually used for this purpose because of their high capacitance. However, electrolytic capacitors are considered to be one of the foremost failure prone elements during a PV inverter. In this paper, a capacitance reduction management strategy is proposed to buffer the DFR energy in single-section Z-supply/quasi-Z-source inverter applications. Without using any additional hardware components, the proposed management strategy can considerably cut back the capacitance demand and achieve low input voltage DFR. Consequently, highly reliable film capacitors can be used. The increased switching device voltage stress and power loss due to the proposed management strategy can also be mentioned. A one-kW quasi-Z-supply PV inverter using gallium nitride (GaN) devices is made in the lab. Experimental results are provided to verify the effectiveness of the proposed method.