AC-to-DC converter

An AC-to-DC converter comprising:

• a power-factor control circuit which is coupled to an AC power source;
• a capacitor which has a first electrode and a second electrode, and whose charge/discharge operation is controlled by said power-factor control circuit;
• and
• a converter which is coupled to said capacitor, said power-factor control circuit including an inductor and a first device, the inductor having first, second and third terminals, the first terminal being coupled to a positive output terminal of said rectifier, the first device being connected to said capacitor in order to supply said capacitor with a current, and which is coupled between said second terminal of said inductor and said first electrode of said capacitor, the power-factor control circuit further including a rectifier coupled to the AC power source, a detector which detects a peak output voltage of said rectifier, a switching device which executes a switching operation for charging said capacitor, and a switching controller which controls the switching operation of said switching device, based on a detected result of said detector, said first device being an n-channel type field effect transistor having a source coupled to said second terminal of said inductor, a drain coupled to the first electrode of said capacitor, and a gate coupled to said third terminal of said inductor.

An AC-to-DC converter comprising:

• a power-factor control circuit which is coupled to an AC power source;
• a capacitor which has a first electrode and a second electrode, and whose charge/discharge operation is controlled by said power-factor control circuit;
• and
• a converter which is coupled to said capacitor, said power-factor control circuit including an inductor and a first device, the inductor having first, second and third terminals, the first terminal being coupled to a positive output terminal of said rectifier, the first device being connected to said capacitor in order to supply said capacitor with a current, and which is coupled between said second terminal of said inductor and said first electrode of said capacitor, the power-factor control circuit further including a rectifier coupled to the AC power source, a detector which detects a peak output voltage of said rectifier, a switching device which executes a switching operation for charging said capacitor, and a switching controller which controls the switching operation of said switching device, based on a detected result of said detector, said first device being a p-channel type field effect transistor having a source coupled to the first electrode of said capacitor, a drain coupled to said third terminal of said inductor, and a gate coupled to said second terminal of said inductor.

An AC-to-DC converter comprising:

• a power-factor control circuit which is coupled to an AC power source;
• a capacitor which has a first electrode and a second electrode, and whose charge/discharge operation is controlled by said power-factor control circuit;
• and
• a converter which is coupled to said capacitor, said power-factor control circuit including an inductor and a first device, the inductor having first, second and third terminals, the first terminal being coupled to a positive output terminal of said rectifier, the first device being connected to said capacitor in order to supply said capacitor with a current, and which is coupled between said second terminal of said inductor and said first electrode of said capacitor, the power-factor control circuit further including a rectifier coupled to the AC power source, a detector which detects a peak output voltage of said rectifier, a switching device which executes a switching operation for charging said capacitor, and a switching controller which controls the switching operation of said switching device, based on a detected result of said detector, said power-factor control circuit including a second device coupled to said inductor and said first device in parallel thereto, in order to transmit a current from said rectifier to said capacitor in a case where a voltage of said capacitor drops, said second device including first and second diodes, the first diode being coupled between one end of said AC power source and the first electrode of said capacitor and the second diode being coupled between other end of said AC power source and the first electrode of said capacitor.