A harmonic balance-based method for predicting line frequency instabilities in PFC converters

Power factor correction (PFC) AC-DC converters are well known nonlinear power electronics systems to exhibit instabilities in the form of period doubling and sub-harmonics oscillations at the line period. This undesirable behavior increases the total harmonic distortion (THD) and therefore can deteriorate enormously the system functioning by decreasing the power factor (PF). In this communication, stability analysis for a boost PFC AC-DC converter is presented. A harmonic balance (HB) approach is used for studying the dynamics of the system. It is found that a singularity in the first order harmonic component model is the main responsible of the first period doubling. This result is then used for analyzing the stability of the complete system. Practical and accurate analytical expressions for stability boundaries are presented.