Soft-Switched Nonisolated High Step-Up Three-Port DC–DC Converter for Hybrid Energy Systems

In this paper, a nonisolated high step-up three-port converter is proposed which provides two separate power flow paths from each input source to the output load. In order to reduce the number of converter components, some components play multiple roles. Accordingly, the energy storage device is charged with the same components which are used in transferring power to the load. In this converter, the coupled inductors technique is used to increase the voltage gain, and to mitigate the leakage inductance effect and to provide soft-switching condition, two active clamp circuits are employed. Since the voltages across the switches are clamped, switches with low voltage stress and consequently low conduction loss can be used. Various converter operating modes are discussed and design considerations are presented. A converter prototype to supply a 150 W–400 V load is implemented and the theoretical analysis is validated by the experimental results.