Bidirectional Soft-Switching Converter With Reduced Current Ripple at Low-Voltage Side

Bidirectional dc-dc converters with storage devices and high-voltage conversion ratio are widely utilized in renewable energy systems in order to manage power flow between renewable sources, storage devices, and load. One of the most important parameters in these converters, which affects the lifetime of storage devices, is the pulsating current flowing through them. This article presents a bidirectional buck/boost converter that employs a coupled inductors technique to increase the voltage conversion ratio while the current in low-side voltage source is continuous. Furthermore, only an active clamp circuit, including a clamp capacitor and an auxiliary active switch, is utilized to create soft-switching conditions for the main switches and absorb the leakage inductance energy of coupled inductors for both high step-up/step-down operating states. In this converter, the soft-switching condition is provided for all switches without any extra element in the power flow direction. Also, all diodes turn off at the ZCS condition, which removes the reverse recovery problem. A low number of elements and fully soft-switching condition for all semiconductor devices have contributed to the converter efficiency. Theoretical analysis of the proposed converter in both operating states is presented in detail, and a 500-W prototype circuit is implemented to verify the validity of the theoretical analysis and converter performance.