Patent ID: 7057375

Claim:
A circuit ( 1 ) for power factor correction comprising: an input terminal ( 10 ) for applying an electrical power (P) having a direct voltage (U) that varies in particular over time with respect to an electrical reference potential (φ), a reference-potential terminal ( 11 ) for applying the reference potential (φ) an output terminal ( 12 ) for drawing a power-factor corrected electrical power (P 1 ), at least two diodes ( 21 , 22 ) connected in series between the input terminal ( 10 ) and output terminal ( 12 ), each connected in the forward direction from the input terminal ( 10 ) to the output terminal ( 12 ), a capacitor ( 13 ) connected between the output terminal ( 12 ) and the reference-potential terminal ( 11 ), and an extra capacitor ( 14 ) having an electrode ( 141 ) connected to an electrical junction ( 20 ) of the two diodes ( 21 , 22 ), and another electrode ( 142 ), and a frequency voltage source ( 15 ) for generating an output voltage which is applied to the other electrode ( 142 ) of the extra capacitor ( 14 ), said output voltage varying substantially between the direct voltage (U) at the input terminal ( 10 ) and the reference potential (φ) at the reference-potential terminal ( 11 ) at a frequency that is higher than a frequency (f 0 ) of the direct voltage (U) at the input terminal ( 10 ), characterized in that the frequency voltage source ( 15 ) comprises: two on/off switches ( 151 , 152 ) connected in series between the output terminal ( 12 ) and the reference-potential terminal ( 11 ), which switch in push-pull mode at such high speed at a frequency (f) of at least 1 Megahertz that at an electrical junction of these two switches ( 151 , 152 ) a square-wave voltage (U 1 ) is generated that varies substantially between the direct voltage (U) at the input terminal ( 10 ) and the reference potential (φ) at the reference-potential terminal ( 11 ) at this frequency (f) of at least 1 Megahertz, and a smoothing device ( 150 ) for smoothing the square-wave voltage (U 1 ) and generating from the square-wave voltage (U 1 ) a smoothed voltage (Uf) which is applied as output voltage of the frequency voltage source ( 15 ) to the other electrode ( 142 ) of the extra capacitor ( 14 ), said smoothed voltage varying substantially between the direct voltage (U) at the input terminal ( 10 ) and the reference potential (φ) at the reference-potential terminal ( 11 ) at the frequency (f) of at least 1 Megahertz, where a capacitance (c pump ) of the extra capacitor ( 14 ) is selected so that the extra capacitor ( 14 ) is charged and/or discharged at the frequency (f) of at least 1 Megahertz of the smoothed voltage (Uf).