Power factor correction circuit

Claim 2

A power-factor-corrected switching power supply that operates over a range of output currents, comprising: a power-factor-corrected cell having an alternating-current input, a switch-control input, and a direct-current output, a direct-current-to-direct-current converter cell having a direct-current input coupled to said direct-current output of said power-factor-corrected cell, a switch-control input, and a direct current output, and a duty-cycle modulator having an input coupled to said direct-current output of said direct-current-to-direct-current converter cell and an output coupled to both said switch control input of said power-factor-corrected cell and to said switch-control input of said direct-current-to-direct-current converter cell, characterized in that both said power-factor-corrected cell and said direct-current-to-direct-current converter cell are constructed and arranged to operate in a discontinuous current mode for substantially said range of output currents of said power-factor-corrected switching supply.

Claim 3

A power-factor-corrected switching power supply that operates over a range of output currents, comprising, a power-factor corrector cell having a pair of alternating-current input terminals to be coupled to the alternating-current utility mains, at least one switch control input, and a pair of output terminals, said cell being arranged to provide unipolar current pulses at said pair of output terminals, a current-fed direct-current-to-direct-current converter cell having a pair of input terminals coupled to the output terminals of said power-factor corrector cell, at least one switch control input, and a pair of direct-current output terminals, and, a duty cycle modulator having an input coupled to the direct-current output terminals of said current-fed direct-current-to-direct-current converter cell and at least one output coupled to the switch control inputs of said power-factor corrector cell and the current-fed direct-current-to-direct-current converter cell, both said power-factor corrector cell and said current-fed direct-current-to-direct-current converter cell constructed and arranged to operate in a discontinuous current mode for substantially said range of output currents furnished by said power-factor-corrected switching power supply.

Claim 4

A power-factor-corrected switching power supply that operates over a range of output currents, comprising, a power-factor corrector cell having a pair of alternating-current input terminals to be coupled to the alternating-current utility mains, at least one switch control input, and a pair of output terminals, said cell being arranged to provide unipolar current pulses at said pair of output terminals, a current-fed direct-current-to-direct-current converter cell having a pair of input terminals coupled to the output terminals of said power-factor corrector cell, at least one switch control input, and a pair of direct-current output terminals, and, a duty cycle modulator having an input coupled to the direct-current output terminals of said current-fed direct-current-to-direct-current converter cell and at least one output coupled to the switch control inputs of said power-factor corrector cell and the current-fed direct-current-to-direct-current converter cell, both said power-factor corrector cell and said current-fed direct-current-to-direct-current converter cell constructed and arranged to operate in a discontinuous current mode for substantially said range of output currents furnished by said power-factor-corrected switching power supply.

Claim 5

A power-factor-corrected switching power supply in accordance with claim 2, wherein said power-factor corrector cell comprises a mains rectifier bridge connected to said alternating-current input terminals, said mains rectifier bridge having first and second bridge outputs, an inductor having a first terminal connected to said first bridge output and a second terminal, a switch connected between said second terminal and said second bridge output, and a diode having a first terminal connected to said second terminal, said diode having a second terminal connected to said current-fed direct-current-to-direct-current converter cell.

Claim 6

A power-factor-corrected switching power supply in accordance with claim 2 wherein said current-fed dc/dc converter cell comprises a storage capacitor having first and second terminals, and further including a first switch having its first terminal connected to the first terminal of said storage capacitor and having a second terminal, a flyback transformer having a primary winding with first and second terminals and a secondary winding with first and second terminals, the first terminal of said primary winding being connected to said second terminal of said first switch, a second switch having a first terminal connected to said second terminal of said primary winding and a second terminal, said second terminal of said second switch connected to said second terminal of said storage capacitor, a diode having a first terminal connected to said first terminal of said secondary winding and having a second terminal, and a filter capacitor connected between said second terminal of said diode and said second terminal of said secondary winding.

Claim 7

A power-factor-corrected switching power supply in accordance with claim 4 wherein said second switch is a short circuit.

Claim 8

A power-factor-corrected switching power supply in accordance with claim 2 wherein said switches are constructed and arranged to respond to said duty cycle modulator to provide a single switch switching action in both said power-factor corrector cell and said current-fed dc/dc converter cell.