A Wide Load Range and Low Current Distortion Digital Boost PFC Converter With Mixed Conduction Mode Operation

In this paper, a digitally controlled boost power factor correction (PFC) converter suitable for universal AC voltage range LCD TV applications is proposed. The proposed mixed conduction mode (MCM) algorithm not only improves the problem of inaccurate sampling of the average current in discontinuous conduction mode (DCM), but also accelerates the dynamic response of the current loop through the duty ratio feedforward (DFF) mechanism. This work reduces conduction losses by sampling average switch current information and improves light-load current distortion in conventional digital average current mode control (ACM) boost PFC converters. The maximum improvement of total harmonic distortion (THD) is about 20%.