Low switching frequency power factor correction circuit

Abstract

A power factor correction circuit for driving a switch of a boost type converter circuit having an AC line frequency input, comprising a sense circuit for sensing and comparing the output voltage of the boost type converter circuit to a reference voltage, a circuit responsive to the output of the sense circuit for providing a drive signal for driving the switch, wherein the drive signal comprises a pulsed signal comprising a pulse grouping during each half cycle of the AC line frequency comprising at least one pulse wherein the number of pulses and frequency of the pulses of the pulse grouping changes with the output of the sense circuit up to a threshold value with the pulse width of the pulses being substantially constant; and when the output of the sense circuit has reached the threshold value, the pulse width of the pulses of the pulse grouping are varied in accordance with the output of the sense circuit.

Description

[0001] Cross References to Related Applications [0002] This application claims U.S. Provisional Patent Application No. 60 / 642,826, filed January 11, 2005, entitled "LOW SWITCHINGFREQUENCY POWER FACTOR CORRECTION CIRCUIT," and filed December 22, 2004, entitled "LOW SWITCHINGFREQUENCY POWER FACTOR CORRECTION CIRCUIT" Priority to U.S. Provisional Patent Application No. 60 / 638,125 and U.S. Provisional Patent Application No. 60 / 578,010, filed June 7, 2004, entitled "LOWSWITCHING FREQUENCY POWER FACTOR CORRECTION CIRCUIT," the disclosure of which is incorporated by reference in its entirety combined here. Background technique [0003] The present invention relates to methods and circuits for power factor correction (PFC). PFC circuits are well known in the art and are used in a wide variety of electronic devices ranging from lighting ballast circuits to switched mode power supplies and motor drivers. [0004] Devices of this type typically require a direct current (DC) input vol...

AI Technical Summary

Problems solved by technology

This low voltage supply is usually obtained through dedicated circuits (usually a flyback switching power supply fed directly from the rectified line, but sometimes a step-down switching regulator) that add additional power to the overall power conversion chain. A lot of cost, and by switching at high frequencies, introduces additional EMI

In other cases, a simple resistive drop is used, which dissipates more power than it delivers to the internal management circuitry

Images