High step‐up passive absorption circuit used in non‐isolated high step‐up converter

Abstract

To obtain a high step‐up gain with high efficiency in distributed power sources application, such as photovoltaic (PV) and fuel cells, a passive absorption circuit with voltage step‐up character is inserted in the interleaved flyback‐forward converter for leakage energy recycle and voltage gain extension. By applying the high step‐up passive‐clamp circuit, the voltage spike on the metal‐oxide semiconductor field‐effect transistor is clamped and the energy stored inside the leakage inductance of the coupled inductor can be recycled to get high‐output voltage. Moreover, it offers another design freedom to obtain higher voltage‐conversion ratio. The operational principle and characteristics of the improved flyback‐forward converter are presented, and verified experimentally with a 500 W prototype converter. The proposed high step‐up passive‐clamp can be widely used in high step‐up DC–DC converter applications, and a new high step‐up topology is deduced to illustrate the theoretical analysis.