Non-isolated high gain DC-DC converter for PV-fed DC microgrid

Abstract

This paper presents a high-gain DC-DC converter for photovoltaic (PV) applications. The proposed high gain DC-DC converter employs two coupled inductors, a voltage-lift capacitor, and two diode-capacitor multiplier cells to achieve a voltage gain of 21.11. The novel hybrid gain extension mechanism was validated by testing a 300 W prototype converter. During experimentation, it yielded an output of 380 V from an 18 V DC input and switched at 50 kHz. Because the switches in the interleaved stage are operated at a duty ratio of 0.5, the input current is ripple-free, and the switch current rating is also reduced. Owing to the location, the voltage stress on the switches was only 10.5% of the output voltage. Due to the adopted gain extension mechanisms, the voltage stress on the diodes was also reduced. The output voltage of the proposed converter is regulated by implementing a closed-loop control. In practice, the converter exhibits a good dynamic response when the line voltage and load current are subjected to step changes. The availability of a common-ground point is an additional advantage. Furthermore, the significant features of the proposed converter were validated by comparing its key parameters with many state-of-the-art converters available in the literature.