Modeling and Controller Design of a Hybrid Input-Parallel Output-Serial Modular DC-DC Converter for High Efficiency and Wide Output Range

Modular input-parallel output-serial (IPOS) DC-DC converter is becoming a crucial solution for high-voltage applications due to its flexible combination form without switching device pressure limitation. It requires high efficiency, fast response, and wide-range output for broader applications. However, the existing solutions cannot simultaneously meet all these requirements. This paper proposes a new hybrid structure with interleaved LLC converters and a DAB converter. The interleaved LLC converters provide the most output voltage with fixed switching frequency and duty cycle, while the DAB converter regulates the output voltage. The wide range output is achieved by switching the LLC converter module and continuously adjusting the output voltage of the DAB converter. Furthermore, a switching control method based on the sliding-mode variable structure is proposed to achieve a smooth and fast output voltage response during the switching process. Finally, a 0.3/0.9-1.8kV, 2kW experimental platform is established to verify the proposed converter's effectiveness and advantages.