AC-to-DC converter

Claim 2

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, and wherein said power-factor control circuit includes a rectifier which is coupled to the AC power source, a detector which detects a peak output voltage of said rectifier, the detector including a circuit for capturing and maintaining said peak output voltage of the 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.

Claim 3

The AC-to-DC converter according to claim 1 , wherein said power-factor control circuit charges said capacitor in accordance with the switching operation of said switching device, such that a voltage in said capacitor will be equal to the peak output voltage detected by said detector or greater than a peak output voltage of said detector by a predetermined amount of voltage.

Claim 4

The AC-to-DC converter according to claim 1 , wherein said power-factor control circuit includes: an inductor which has a first terminal, coupled to a positive output terminal of said rectifier, and a second terminal; and a first device which is 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.

Claim 5

The AC-to-DC converter according to claim 3 , wherein said switching device is coupled between said second terminal of said inductor and said second electrode of said capacitor.

Claim 6

The AC-to-DC converter according to claim 3 , wherein said first device is a diode having an anode coupled to said second terminal of said inductor and a cathode coupled to the first electrode of said capacitor.

Claim 7

The AC-to-DC converter according to claim 3 , wherein said inductor has a third terminal; and said first device is 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.

Claim 8

The AC-to-DC converter according to claim 3 , wherein said inductor has a third terminal; and said first device is 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.

Claim 9

The AC-to-DC converter according to claim 3 , wherein said power-factor control circuit includes 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.

Claim 10

The AC-to-DC converter according to claim 8 , wherein said second device is a diode having an anode coupled to a positive output terminal of said rectifier and a cathode coupled to the first electrode of said capacitor.

Claim 11

The AC-to-DC converter according to claim 8 , wherein said second device includes: a first diode coupled between one end of said AC power source and the first electrode of said capacitor; and a second diode coupled between other end of said AC power source and the first electrode of said capacitor.

Claim 12

The AC-to-DC converter according to claim 8 , wherein said power-factor control circuit: controls a charge/discharge operation of said capacitor in accordance with the switching operation of said switching device, in a case where output power of said AC-to-DC converter is equal or less than predetermined reference power; and controls the charge/discharge operation of said capacitor by a current flowing to and through said second device, in a case where the output power of said AC-to-DC converter is equal to or greater than the reference power.

Claim 13

The AC-to-DC converter according to claim 11 , wherein the reference power is within a range between one sixteenth and half of maximum power consumption.

Claim 14

The AC-to-DC converter according to claim 1 , wherein said AC-to-DC converter includes a voltage controller for controlling an output from said converter.

Claim 15

The AC-to-DC converter according to claim 1 , wherein said detector includes a semiconductor element which has an anode coupled to a positive output terminal of said rectifier, and a cathode; and a capacitive element which is coupled between the cathode of said semiconductor element and a negative output terminal of said rectifier.

Claim 16

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.

Claim 17

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.

Claim 18

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.

Claim 19

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.

Claim 20

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.

Claim 21

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.