A high step-up DC/DC converter for PV panel application

In this paper, a high step-up DC/DC converter is proposed, which can boost low PV panel voltage or battery voltage to a high level so as to power the dc side of grid-connected PV inverter. The proposed converter is composed of an inductor, a power switch, and a coupled inductor and is derived from the integration of buck-boost and flyback for high voltage-gain achievement. Even though it possesses buck-boost and flyback features, there is no the problem of reverse voltage polarity and the energy stored in the leakage inductance can be recycled without additional active clamp circuit. Furthermore, since the input source, active switch, and output port are in common ground, the proposed converter has the advantages of easy control-circuit design and simple control-circuit configuration. In particular, the proposed converter can be expanded to multi-layer topology to stack up output voltage such that a much higher voltage gain can be obtained. A prototype, of which input voltage is 48V, output voltage is 400V and power rating is 200W, is built to validate the proposed converter. Experimental results have verified the feasibility and functionality of the proposed converter.