Bidirectional High Step-Up/Down DC/DC Converter With a Coupled Inductor and Switched Capacitor

This article is a study of bidirectional DC/DC converter for the energy storage systems. Non-isolated interleaved bidirectional high step-up/down (NIBH) DC/DC converter consists of a coupled inductor and a switched capacitor. The NIBH converter has important features such as low ripple current on the low voltage side, low cost, low component count, high voltage conversion ratio, low voltage stress, and soft switching operation of switches. Two coupled inductors are connected in parallel to the low voltage side to have low ripple current and increase the turns ratio to achieve high step-up/step-down voltage gain. The switched capacitors can be stacked in series with the high voltage side to achieve high voltage gain, and the active clamp circuit enables the switches to reduce conduction and switching losses with low voltage stress and soft switching operation. To verify the theoretical analysis and performance of the proposed converter, a 650W prototype circuit was implemented in the laboratory.