A Switched-Capacitor Interleaved Bidirectional Converter With Wide Voltage-Gain Range for Super Capacitors in EVs

A switched-capacitor interleaved bidirectional dc-dc converter that combines a three-phase interleaved structure with switched-capacitor cells is proposed. The converter features a wide voltage-gain range, low-current ripple on the low-voltage side, low voltage stresses across power switches, an absolute common ground between input and output, and can be easily extended into a topology family. The operating principle and power switch voltage and current stresses are analyzed in detail. An 800 W prototype with a wide voltage-gain range ( U high = 400 V, U low = 30-100 V) is described, demonstrating a maximum efficiency of 95.8% in the step-up mode and 95.9% in the step-down mode.