Research on Smooth Soft-Start Control of Two-Switch Buck-Boost

The two-switch Buck-Boost converter has an ultra-wide voltage regulation capability and low switching loss, which widely used in airborne power supply. Since the gain curve of TSBB is quite different in CCM and DCM states, with traditional soft-start control method, the soft-start waveform of output voltage will have platform and oscillation under light load conditions. In this paper, the DCM gain and the reasons for the platform and oscillation are analyzed. A novel soft-start control method is proposed to achieve smooth soft-start under different load conditions. An 800 W prototype is built using the TSBB+LLC-DCX topology to verify the effect of the proposed smooth soft-start control strategy.