Waveform Programming Control for Four-Switch Buck–Boost Converter With Minimum RMS Current

This article proposes a waveform programming control strategy for the four switch Buck–Boost converter. By adopting the quadrilateral inductor current modulation method, the degree of freedom is optimized, thereby enhancing the control accuracy. Zero-voltage switching is achieved within a wide input voltage and load range. Without changing the modulation mode, smooth switching between Boost and Buck modes can be realized, avoiding complex control logic during transient. The complete loss distribution is constructed in the structure, optimizing the system design, improving efficiency, and achieving the lowest root mean square value of inductor current. Under the dual-loop control mode of voltage and current, the debugging difficulty is greatly reduced, and the robustness and response speed of the converter are enhanced. Finally, a 20 kW FSBB converter experimental prototype is built to verify the correctness of the control scheme and the feasibility of the control strategy.