A Novel High Step-Up High Efficiency Interleaved DC-DC Converter With Coupled Inductor and Built-In Transformer for Renewable Energy Systems

This article proposes a novel step-up interleaved dc-dc converter that is suitable for renewable energy systems. Coupled inductor and built-in transformer voltage multiplier cell are applied to extend the voltage gain while increasing the power density. Hence, the step-up ratio can be adjusted by the turns ratios of the coupled inductor and the built-in transformer. Compared with the other converters with only built-in transformer or only coupled inductor, the combination of these techniques gives an extra degree of freedom to increase the voltage gain. The configuration of the proposed converter not only reduces the current stress through the components, but also the input current ripple is maintained at low values that lengthen the life time of the renewable power source. The energy of the leakage inductors is successfully recycled and the high-voltage spikes across the power switches are avoided, which improves the conversion efficiency. Due to the reduced voltage stress, low-voltage power MOSFETs can be adopted for reduction of conduction losses and cost. The principle operation and steady-state analysis are given to explore the advantages of the proposed converter. Finally, a 1-kW prototype with 45-675 V voltage conversion is built to demonstrate the effectiveness of the proposed converter.