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In this study, a novel soft-switched high step-up DC/DC converter is presented. This converter is suitable to be employed in photovoltaic and fuel cell systems. The proposed topology is based on coupled inductors and switchedcapacitor techniques to provide high step-up gain. Also, due to high conversion ratio, and symmetrical structure of the proposed topology, the voltage stress of semiconductor elements is low; therefore, high performance metal-oxidesemiconductor field-effect transistors with low ON-resistance, and also low-voltage rating diodes can be utilised to reduce the circuit cost, conduction, and reverse-recovery losses which improve the converter efficiency and power density. Furthermore, by adopting an active clamp circuit, the stored energy in the leakage inductance of coupled inductors is recycled and zero-voltage-switching turn-on condition for both main and clamp switches are provided. Operating principle and steady-state analysis of the converter are discussed in detail. Finally, an experimental prototype of the proposed converter with 200 W output power is implemented which verifies the theoretical analysis.

A new interleaved high step-up DC-DC converter is presented in this study which integrates coupled inductors and voltage multipliers techniques into interleaved structure to provide high voltage gain without extreme duty cycle. The voltage stress across power metal-oxide-semiconductor field-effect transistors is very low, so low voltage rating switches with lower R ds (on) can be used. A modified version of winding cross-coupled inductors technique is employed to minimise the input current ripple, and also the reverse recovery problem of the output diodes is alleviated because of the leakage inductance of the coupled inductors. Also, the leakage energy is absorbed and recycled to the output by the passive clamp scheme. In addition, automatic current sharing performance between the interleaved phases is established without any extra circuit. The operating principles of the proposed converter are explained and the theoretical analysis is provided, and in order to verify the effectiveness of the proposed converter, a 170 W, 30-360 V laboratory prototype is implemented.

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This study introduces a soft-switching non-isolated bidirectional DC-DC converter with high voltage conversion ratio and low voltage stress across semiconductor devices. The presented topology is well suited for high step-up/step-down applications. By integrating coupled inductors and switched capacitors techniques, a high step-up/step-down voltage gain is achieved. Active clamp circuits are employed in both high step-up and high step-down operating states to recycle the leakage inductance energy and realise zero-voltage-switching condition for all switches to mitigate the switching losses and improve efficiency. Also, the reverse recovery problem of the body diodes is completely alleviated owing to zero-current-switching performance. The operation principles and theoretical analysis of proposed converter are presented in details. Finally, the experimental results of a 200 W prototype circuit are provided to confirm the validity of the proposed topology.