Abstract
DESIGN AND CONTROL OF LOW FREQUENCY RIPPLE FREE CURRENT FOR QUASI Z-SOURCE PV GIRD CONNECTED INVERTER
G. Neelakrishnan*, D. Chellapandi, R. Satheesh, K. Tamil selvan
ABSTRACT
In single-phase photovoltaic (PV) system, there is double-frequency power mismatch that exist between the dc input side and the ac output side. The double-frequency ripple (DFR) energy needs to be buffered by passive network. Otherwise, the ripple energy will flow into the input side and adversely affect the PV energy harvest. In a conventional PV system, electrolytic capacitors are usually used for this purpose due to their high capacitance. However, electrolytic capacitors are considered to be one of the most failure prone components in a PV inverter. In this paper, a capacitance reduction control strategy is proposed to buffer the DFR energy in single-phase Z-source/quasi-Z-source inverter applications. Without using any extra hardware components, the proposed control strategy can significantly reduce the capacitance requirement 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 control strategy will also be discussed.
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