An Observer based Algorithm for Input Current Quality Optimization in AC/DC Boost Converters

Modern power supplies include AC/DC boost converters as active power filters for improving Power Factor (PF) and Total Harmonic Distortion (THD). Traditional methods comprising Proportional-Integral (PI) regulator cascaded with a notch filter perform well in bus voltage regulation. This paper presents a disturbance observance-based controller to replace the notch-based controller in on-time controlled Critical Conduction Mode (CrCM) quasi-resonant topologies. The paper highlights the improvement in input current quality in terms of PF and THD using the proposed controller and shows comparative results to a notch controller. The paper presents theory behind the proposed controller, discretization steps for implementing in digital domain, and simulation results in a mixed-signal environment. The paper concludes by providing results of the proposed algorithm in an embedded power control application. Simulation and hardware results confirm the suitability of the proposed methodology for AC/DC boost converters to improve input current quality in terms of PF, THD, and harmonics as per IEC/EN 61000-3-2 Class C used in lighting applications.