High Step-Up/Down Switched-Capacitor Based Bidirectional DC-DC Converter

In this paper, a new non-isolated switched-capacitor/switched-inductor based bidirectional dc-dc transformerless converter with high voltage conversion ratio is proposed. The proposed converter is able to provide improved voltage gain with lower voltage stresses on switches and its number of components is less than other compared similar switched-capacitor bidirectional DC-DC converters. In addition, the voltage stresses on switches and diodes of the proposed converter is low, as a result, the switching losses are decreased. Due to the expandable structure of the proposed converter, the voltage gain of the proposed converter can be increased by adding more diode-capacitor cells at output side. In this paper, the proposed converter is analyzed theoretically during a switching period which has two operating modes for both boost and buck operations. Moreover, the average current through the switches, diodes and inductors, voltage stresses on switches and diodes, voltage gain, maximum and minimum current of switches and diodes are calculated for boost and buck operations. Finally, in order to verify the accuracy performance of the proposed converter, a 200-W 25 to 448 V prototype is implemented practically.