A New Single-switch, Electrolytic Capacitor-less Step-up DC/DC Converter Topology with Complete Soft-switching Operation for Photovoltaic Application

A new quasi-resonant, soft-switched electrolytic capacitor-less step-up DC/DC converter for photovoltaic applications is presented in this paper. The proposed circuit is a coupled-magnetics based topology that requires only a single switch. The proposed circuit is able to achieve zero voltage switching (ZVS) turn-on and zero current switching (ZCS) turnoff for the switch. Since the input inductor in the proposed circuit operates in continuous conduction mode, the required input capacitance is reduced and hence, this allows small-size film capacitor to be used. The proposed circuit is able to achieve a large step-up gain while minimizing the ratio between the peak switch voltage and the circuit output voltage. In addition, the proposed circuit is able to achieve maximum power operation with PV panels through the use of variable switching frequency control. Results from a simulated 140W, 150 kHz system and a proof-of-concept hardware prototype are provided to highlight the merits of the proposed circuit.