The time-domain analysis for constant on-time critical mode boost-type PFC converters

This paper proposed a time-domain mathematical analysis for the constant on-time (COT) critical mode (CRM) boost-type power factor correction (PFC) converter with and without zero voltage switching (ZVS) or valley switching (VS). The mathematical expression for the unfiltered input current function is derived and used to calculate the total harmonic distortion (THD). Then, the input filter is considered to calculate the filtered THD. The derived mathematical equations will help users to understand the causes of the current distortion and to design an appropriate filter to reduce the THD. The accuracy of the proposed time-domain analysis is verified by different simulation software, Octave and SIMPLIS. The calculated THD values by the proposed mathematical expressions and by the circuit simulation software are found to be consistent.