Power supply comprising means for improving the power factor

A power supply for converting an alternating voltage supplied by an electric mains into a desired voltage, comprising:

• first rectifier means having first input terminals operative to receive the alternating voltage and first output terminals for delivering a first pulsating direct voltage, a buffer capacitor connected parallel to the first output terminals, an inverter with input terminals connected to the buffer capacitor, second rectifier means with input terminals connected parallel to the first input terminals and second output terminals for delivering a second pulsating direct voltage, and a flyback converter with input terminals connected to the second output terminals and output terminals connected parallel to the buffer capacitor, wherein the flyback converter is operative to deliver a maximum power which is substantially lower than the maximum power of the first rectifier means, and the flyback converter includes a transformer with a primary and a secondary winding, the primary winding being connected in series with a switching element which comprises a control electrode, the primary winding and the switching element forming a primary series circuit connected to the flyback converter input terminals, the secondary winding being connected in series with a rectifier element to form a secondary series circuit connected to the flyback converter output terminals, the control electrode of the switching element being connected to a control circuit which is operative to supply the control electrode with a first control signal in the form of a series of pulses.