Optimum Current Ripple Control With Inherent Mixed Conduction Mode to Improve Efficiency in Interleaved Totem-Pole PFC Converters

This article proposes an optimum current ripple (OCR) control strategy to improve interleaved totem-pole power factor correction (PFC) conversion efficiency over wide operating conditions. A generalized analytical formulation is derived to express instantaneous PFC losses as function of the inductor current ripple, which is selected as the primary control variable. An inherent mixed conduction mode (MCM) operation is obtained from the applied ripple profile, which is determined offline to minimize the PFC total losses, under given switching-frequency and peak-current constraints. A low processing implementation is performed in a standard microcontroller combining hysteresis current control and multidimensional look-up tables. Compared to other control methods, the proposed OCR-MCM shows significant efficiency improvements in a 7-kW three-channel interleaved PFC prototype, at different input/output voltages and loads. Optimal results are achieved in terms of power factor and current total harmonic distortion.