Family of cascaded high-voltage-gain bidirectional switched-capacitor DC-DC converters

High-voltage-gain step-up DC-DC converters are required for the applications of distributed energy resources (DERs). A family of bidirectional switched-capacitor (SC) converters with high gain ratio of any positive integer are proposed in this paper. These converters are of high efficiency, easy to control, and are with low output voltage ripple of less than 1%. The proposed converters are also capable of delivering bidirectional power, which is a key requirement for the applications with battery storage. A prototype of 9-time SC converter at 20 V input voltage, 100 W output, 75 kHz, is built and tested. Experiment results show that the maximum efficiency of the 9-time SC converter is over 98% without driver´s loss and the efficiency over the entire load range between 25 W and 100 W is over 95.5% including the driver´s loss.