Reconfigurable Resonant DC-DC Bidirectional Converter for Wide Output Voltage Applications

The bidirectional DC-DC converters are essential for various applications such as electric vehicles, energy storage systems and distributed energy systems. The conventional bidirectional DC-DC converters has limited soft switching region, which further reduces the wide output voltage operation. The bidirectional resonant converters are most suitable for wide voltage applications due to its gain characteristics and soft switching capabilities. However, the LLC/CLLC-based topologies can provide wide output voltage by operating the converter in wide frequency range, which affects the performance of the converter. This article proposes a reconfigurable resonant DC-DC bidirectional converter for wide output voltage applications. This converter integrates two resonant networks (CLLC and CLLC-C) using topology morphing for wide output voltage operation. The converter has an additional feature of soft switching for the reverse power transfer. The gain characteristics shows the regulation of the output voltage over a wide range within a narrow operating frequency. In addition, the converter has the inherent soft startup capability to prevent inrush currents or voltage spikes during startup. The detailed analysis and design of the proposed reconfigurable converter that can operate over a wide range of output voltages is presented in this article. Additionally, a laboratory prototype of the 500 W is developed to validate the operation of the proposed converter.