Single-phase unity power factor rectifier, rooted on a shunt active filter

This paper presents a new technique to improve the input power factor of a single-phase rectifier followed by an inductive filter. It consists in the employment of a two-quadrant active power filter, based on a conventional bidirectional DC-DC converter, connected to the output side of the diode bridge. This technique allows the extension of this rectifier range operation in the continuous conduction mode. Circuit description, operation principle, modeling, design and simulation results are presented in this paper. A laboratory prototype was designed and built, with the following specifications: input voltage: 220 VRMS; output voltage: 200 VDC; rated power: 3 kW; switching frequency: 100 kHz. By the experimental results obtained, the system presented a unity power factor and an efficiency of 95% at full load, while the maximum efficiency value was 98% at 2 kW.