Efficiency-Oriented Optimized Design and Control of Hybrid FSBB–CLLC Converters With Partial Power Processing Capability

Combining the highly efficient CLLC topology with the exceedingly flexible four-switch buck–boost (FSBB) topology, this article introduces a novel hybrid FSBB–CLLC converter incorporating partial power processing capability. This hybrid structure utilizes FSBBs to regulate its output voltage by adjusting its duty cycle, handling a small portion of the total power, and providing a fast dynamic response. Meanwhile, the CLLC in the structure operates in a complete resonant state to ensure high system efficiency. By sharing a bridge arm between the FSBB and the CLLC, where one arm from each system serves a similar function, the number of switches utilized is significantly reduced, resulting in higher system efficiency. In addition to the structural improvements, to achieve a higher average system efficiency under different loads, this article presents an efficiency-based parameter design methodology. Furthermore, phase shift, an additional control freedom of FSBB, is employed to further enhance the system's overall efficiency; however, calculating the relationship between efficiency and phase shift can be burdensome, especially in real-time controllers. To address this issue, this article proposes a fitting-model-based maximum efficiency tracking approach to reduce calculation complexity. Ultimately, experimental results demonstrate the effectiveness of the proposed design, highlighting its enhanced performance.