Patent ID: 8797004

Claim:
A PFC (power factor correction) device for shaping an input current of a power converter, the PFC device comprising: a receiving module for receiving a rectified input voltage Vrec derived from an AC (alternating current) input voltage VAC; a load determining module for determining a load value L which represents a power drawn by a load supplied by the power converter; a reference determining module for determining a reference offset voltage Voff in accordance with the load value L; a reference waveform module for generating a reference waveform Iref, wherein the reference waveform Iref is proportional to Vrec−Voff; a current shaping module for shaping the input current of the power converter to follow the reference waveform Iref; and a control module for controlling the current shaping module to operate over a conduction interval α, in which the rectified voltage input Vrec is higher than a value substantially equal to said reference offset voltage Voff, during each positive and negative half cycle of the AC input voltage; wherein a duration of the conduction interval α is controlled in accordance with the load value L.