Digital Voltage Control of Boost CRM PFC AC/DC Converters with TRIAC Phase Control Dimmer

Abstract

This paper presents a digital voltage control scheme for boost critical conduction mode (CRM) power-factor-correction (PFC) AC/DC converters with TRIAC phase control dimmer to use in the lighting equipment ex. LED or fluorescent lamp. The TRIAC is a standard type of dimmer and work fine with resistive load such as ordinary Tungsten filament light bulb (incandescent lamp), however, for non-resistive lighting sources, a well-designed AC-DC converter must be designed to provide good power quality as well as wide linear non-flickering dimming control range. A variable PFC output voltage modulation method is proposed to enhance the dimming control range. The TRIAC dimmer will cause switching oscillations due to the PFC input filter, a damper circuit is designed to minimize this effect. The proposed control scheme has been verified by using simulation software PSIM in applications to a 50 W prototype of boost CRM PFC AC/DC converter with TRIAC phase control dimmer. Simulation and experimental results are given to illustrate the feasibility of the proposed control scheme.