An adaptive digital controller for the mixed conduction mode boost power factor correction converter

This paper presents a novel adaptive mixed conduction mode (MCM) digital controller to realize total harmonic distortion (THD) and power factor improvements in boost power factor correction (PFC) converters operating over a wide load range in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) during a single ac line half cycle. By using the integrated comparators found on many digital signal processors (DSPs), a digital DCM detection method allowing a dynamic selection of appropriate compensators gives THD and power factor performance improvements when compared to a conventional digital control technique. At an output power of 98 W, an experimental 650 W boost PFC converter operating in MCM controlled by a TMS320F28035 provides a THD reduction of 40.2% and power factor improvement of 1.5% over a conventional digital controller.