Dual-mode control of cascade buck-boost PFC converter

Abstract

This paper proposes a simple and effective control method for unity-power-factor rectifiers based on cascade buck-boost (CBB) converter. The proposed "dual-mode" control method effectively exploits the additional degree of control freedom provided by the CBB converter and achieves sinusoidal input current while providing a tight output voltage regulation. In addition, the control method also de-couples the output voltage control loop from the often-slow input-current-reference generator, resulting in excellent output voltage dynamic response. The theoretical analysis, choice of circuit elements, and the applicable range of operating conditions of the proposed control scheme are also presented in the paper. Excellent steady-state and transient performance of the converter are demonstrated through simulation and experimental results. A qualitative comparison of the converter performance with the popular PFC converters has also been done.