High-gain Boost-Boost-Flyback converter for renewable energy sources applications

In this paper, a non-isolated step-up high-gain DC-DC converter for renewable energy sources applications is proposed. The circuit is composed by a conventional Boost stage and a Boost-Flyback stage, thereby it is possible to attain a high-voltage gain without compromising the converter efficiency. The pulse-width modulator (PWM) applies the same gate drive signals to both switches, which are connected to the same reference as the load and the source, simplifying the gate drive circuitry. The principle of operation and the analysis of the converter in continuous conduction mode will be discussed thoroughly. To validate the analysis, some simulations are presented herein and a 350 W prototype was designed, built and tested in laboratory with an input voltage of 24 V, an output voltage of 400 V and a switching frequency of 40 kHz.