Analysis and Performance Evaluation of Interleaved DCM/CCM Boundary Boost PFC Converters Around Zero-Crossing of Line Voltage

In this paper, causes of improper interleaving of two DCM/CCM boundary boost PFC converters around zero crossing of the line voltage are analyzed. The converters have a master-slave relationship. The slave is synchronized to the turn-on instant of the master by using an open-loop interleaving method. It is shown that phase shifting the gate drive signals of the two stages by 180° does not provide 180° phase-shift between the individual inductor currents, which is the real purpose of interleaving. Fortunately, the improper interleaving around zero crossing of the line voltage does not deteriorate the power factor (PF) and total harmonic distortion (THD). It is shown that although the interleaving method can be improved to achieve close to 180 phase shift between the master and slave currents even around zero crossing of the line voltage, the improved interleaving has only a minor effect on the PF and THD.