High voltage step-up integrated double Boost–Sepic DC–DC converter for fuel-cell and photovoltaic applications

In this paper, an integrated double boost SEPIC (IDBS) converter is proposed as a high step-up converter. The proposed converter utilizes a single controlled power switch and two inductors and is able to provide high voltage gain without extreme switch duty-cycle. The two inductors can be coupled into one core for reducing the input current ripple without affecting the basic DC characteristic of the converter. Moreover, the voltage stresses across all the semiconductors are less than half of the output voltage. The reduced voltage stress across the power switch enables the use of a lower voltage and RDS-ON MOSFET switch, which will further reduce the conduction losses. Whereas, the low voltage stress across the diodes allows the use of Schottky rectifiers for alleviating the reverse-recovery current problem, leading to a further reduction in the switching and conduction losses. A detailed circuit analysis is performed to derive the design equations. A design example for a 100-W/240 Vdc with 24 Vdc input voltage is provided. The feasibility of the converter is confirmed with results obtained from simulation and an experimental prototype.