A Novel High Step-up/Step-down Transformer-Less Bidirectional DC-DC Converter for Energy Storage Systems

In this article, a new type of bidirectional DC-DC converter with ultra-high voltage conversion capability applied in the field of energy storage systems is proposed. The new converter consists one inductor, two capacitors, and four power semiconductors. Compared with the traditional buck-boost converter, the proposed topology doubles the effective duty cycle, and can obtain a higher voltage gain without using extreme duty cycles. In addition, lower voltage stress of semiconductor devices can also be achieved. The control strategy is uncomplicated due to the simple structure. The steady-state analysis and small signal analysis of the topology in continuous conduction mode are introduced in detail, and the voltage stress of the components in the topology is deduced. The novel structure compared with the structure in the existing literature, it shows the excellent performance of the proposed converter. Finally, a 4S-400V/400-48V simulation model was established to verify the reliability and correctness of the proposed topology.