DCM Buck-Buck/Boost PFC Converter with Segmented Fixed Duty-Cycle Control

A discontinuous conduction mode (DCM) integrated buck-buck/boost power factor correction (PFC) converter with segmented fixed duty-cycle control (SFDCC) scheme is proposed in this paper. This converter features high power factor (PF) and low total harmonic distortion (THD). The high PF is achieved by adjusting the duty-cycles of buck and buck/boost switches. A fixed duty-cycle ratio control (FDCRC) method is further proposed for simplifying the control circuit. This paper analyzes the operating principle of the converter with conventional constant duty-cycle control (CDCC) and SFDCC. Compared with the CDCC, the SFDCC can also reduce the root mean square (RMS) value of the inductor current and improve the efficiency of the converter. A 120-W prototype is built up to verify the effectiveness of the proposed control method.