A Nonisolated Switched-Capacitor-Based Bidirectional DC–DC Converter With Low Input Current Ripple and Common Ground for EV Application

In electric vehicle applications, bidirectional DC-DC converters with low input current ripple are ideal due to the sensitivity and charging characteristics of energy storage systems like batteries and super-capacitors. This paper introduces a non-isolated bidirectional converter that hybridly integrates a coupled-inductor and switched-inductor-capacitor cell at the input with a traditional bidirectional DC-DC topology, while quasi-hybridly incorporating a switched-capacitor (SC) cell at the output. The proposed converter achieves high voltage gain, minimal input current ripple, low semiconductor voltage stress, and high efficiency. It further offers key features such as low component count, shared common ground between the input and output to mitigate electromagnetic interference (EMI), and soft-switching capability in both buck and boost modes, which reduce switching losses, cooling demands, system volume, and cost, making it well-suited for EV applications. Steady-state analysis and design of the proposed converter are provided, with its advantages assessed through a comparison with other similar structures. Furthermore, its Controllability is enhanced through an improved pole-placement control strategy. Finally, the theoretical results are verified by experimental results obtained from a 300-W laboratory prototype operating at 50 kHz and a 400-V output. Theoretical maximum efficiencies at 150-W are 97.72% in boost mode and 96.88% in buck mode.