An Extendable Transformer-Less Bidirectional DC–DC Converter With High Voltage Gain and Zero-Current Ripple

In this article, a novel extendable nonisolated bidirectional dc–dc converter based on a quadratic circuit with a switched-capacitor and a zero-current ripple cell is proposed. First, the proposed bidirectional dc–dc converter achieves a wide voltage conversion ratio and low voltage stress on semiconductor devices by combining the quadratic circuit with a switched-capacitor cell. Second, when the switching frequency of the converter is much higher than the resonant frequency of the system, the zero-current ripple cell exhibits a highly effective suppression of current ripple. Furthermore, a family of expandable bidirectional dc–dc converters is derived by embedding n extendable modules, thereby improving the voltage transfer ratio of the converter. The working principle and steady-state characteristics under boost and buck modes are analyzed in detail with the synchronous rectifier modulation strategy. Finally, a 200 W experimental platform is established to verify the infallibility of the theoretical analysis.