Enhanced Constant-On-Time Control for DCM/CCM Boundary Boost PFC Pre-regulators: Implementation and Performance Evaluation

This paper shows an innovative improvement of the constant on time (COT) control of transition mode boost PFC. The proposed control method employs a minimum current comparator to improve the harmonic distortion and power factor of the converter while maintaining the same complexity of the constant on time control. An overview and the enhancements of this method are presented in comparison to the standard COT. The algorithms, the equations, the analog and digital implementations are detailed for both improved methods. The comparison of the standard, enhanced COT (eCOT) and ramp enhanced COT (ReCOT), in terms of THD, PF and computational load, are shown with physical measures based on real implementations. The measures confirm the analysis and the good performance reached.