A high step-up DC-DC converter based on coupled inductor and diode-capacitor with improved voltage gain and efficiency, and reduced voltage stress for photovoltaic systems

This paper proposes a nonisolated high step-up dc-dc converter, which optimally integrates coupled inductor, and diode-capacitor and provides superior features such as high gain, high efficiency, and low voltage stresses on power switches. Moreover, the common ground between the input and output of the proposed converter makes it appropriate for photovoltaic systems. It consists of two power switches, one inductor, one coupled inductor (CI), four diodes, and four capacitors. The power switches are exposed to low voltage stresses and are selected from low voltage ratings and low on-resistance semiconductors. The topology, operating principle, complete steady-state and ac small-signal models, loss model, and design criterion are presented and described in detail. Also, the proposed topology is compared with other previous topologies. In order to evaluate the performance of the proposed converter, a 400 V/400 W experimental prototype has been designed and built. Experimental results validate the theory and show the converter produces high gain (14.25 times in the full-load condition tested) and operates with high efficiency (94.9% in the full-load condition).