A new bidirectional DC-DC converter with a high step-up/down conversion ratio for renewable energy applications

A new bidirectional DC-DC converter based on switched-capacitor-inductor cell was proposed. It features: high step-up/down conversion ratio with a moderate duty cycle; low voltage stress on the switches; non-pulsating input current (step-up mode); easiness of control and driving circuit. The proposed converter contains five switches and four reactive elements (two capacitors and two inductors). It can achieve quadratic-like conversion ratio. Steady-state for both step-up mode and step-down mode were analyzed in this paper and the proposed converter was simulated by PSIM. Results of step-up mode from 66V to 400V, or step-down mode from 400V to 66V, matched the theoretical analysis. Further examinations and experiments can be done to optimize the performance of the circuit. The proposed converter can be widely used as front-end to renewable energy system, e.g. between battery and DC bus, where bidirectional power flow is required.