Analysis and Modeling of a Four-Switch Buck-Boost Converter with PWM plus Phase-Shift Control

Four-switch buck-boost (FSBB) converter features positive output voltage and low voltage stress of power switches. In this paper, the operating mode of FSBB converter, the optimal switching sequence to achieve zero-voltage- switching (ZVS) and minimize the ripple of the inductor current, and the control method with PWM plus phase-shift control are all be introduced. In order to design the parameters of the analog control loop, the averaged small signal model of FSBB converter is derived to provide the theoretical basis in this paper. The simulation and experiment results verify the correctness of the average small signal model.