Analysis and implementation of a new PFC digital control method

A predictive algorithm for digital controlled PFC is introduced in this paper. Based on this algorithm, all of the duty cycles required to achieve unity power factor in a half line period can be calculated by the DSP in advance. The main advantage of this digital control PFC method is that the high switching frequency of the PFC can be achieved because it does not directly depend on the processing speed of DSP. The small signal model is set up for the purpose of designing the voltage loop and analyzing the dynamic performance of DSP controlled PFC system. Input voltage feed forward compensation makes the output voltage insensitive to the input voltage variation and guarantees the input current sinusoidal even if the input voltage is distorted. Simulation results show that the predictive algorithm for digital controlled PFC works well.