Single Switch Nonisolated Ultra-Step-Up DC-DC Converter With an Integrated Coupled Inductor for High Boost Applications

This paper introduces a new single-switch nonisolated dc-dc converter with very high voltage gain and reduced semiconductor voltage stress. The converter utilizes an integrated auto-transformer and a coupled inductor on the same core in order to achieve a very high voltage gain without using extreme duty cycle. Furthermore, a passive lossless clamp circuit recycles the leakage energy of the coupled magnetics and alleviates the voltage spikes across the main switch. This feature along with low stress on the switching device enables the designer to use a low voltage and low RDS-on MOSFET, which reduces cost, as well as conduction and turn on losses of the switch. The principle of operation, theoretical analysis, and comparison supported by some key simulation and experimental results of a 500 W prototype are presented.