Power factor correction circuit arrangement

• US 6,531,854 B2
• Filed: 03/30/2001
• Issued: 03/11/2003
• Est. Priority Date: 03/30/2001
• Status: Expired due to Fees

• Current Assignee: Champion Microelectronic Corporation
• Original Assignee: Champion Microelectronic Corporation
• Inventors: Hwang, Jeffrey H.
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US09/823,639
• Publication Number:
  US 20020140407A1
• Time in Patent Office: 711 Days
• Field of Search: 323/222, 323/237, 323/242, 323/282, 323/283, 323/284, 323/285, 323/286, 323/288, 323/299, 323/300, 323/351
• US Class Current: 323/285
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

A power factor correction circuit arrangement. A rectified alternating-current (AC) input signal may be applied across inputs of a voltage converter circuit, such as a boost converter. Current drawn by the voltage converter may be sensed to form a first sensing signal that is representative of the current. The rectified input voltage may be converted to a second sensing signal that is representative of the AC input signal. Switching in the power converter is adjusted in a first feedback loop to equalize the first and second sensing signals and, thus, the current drawn is regulated to remain in phase with the AC input signal. A feedback signal adjusts switching so as to regulate the output voltage level of the voltage converter in a second feedback loop and, thus, controls power delivered to the load.

Claims

1. A power factor correction converter, comprising:

a switch for modulating an input current received from a rectified alternating-current supply so as to form an output voltage across an energy storage element in response to a switch control signal;

a series-coupled resistor pair coupled across inputs of the alternating-current supply and having an intermediate node;

a first feedback loop for forming the switch control signal in response to a signal formed at the intermediate node; and

a second feedback loop for adjusting a resistance of the series-coupled resistor pair in response to a level of the output voltage.

2. The power factor correction converter according to claim 1, further comprising a current sensing resistor coupled between a ground node and one of the inputs of the alternating-current supply.

3. The power factor correction converter according to claim 2, wherein the intermediate node is held to a virtual ground level.

4. The power factor correction converter according to claim 1, wherein the first feedback loop comprises an integrator coupled to receive the signal formed at the intermediate node.

5. The power factor correction converter according to claim 1, wherein a comparator compares an integrated signal formed by the integrator to a periodic ramp signal.

6. The power factor correction converter according to claim 5 wherein the periodic ramp signal has a fixed amplitude.

7. The power factor correction converter according to claim 5 wherein the periodic ramp signal has a varying amplitude that is representative of a level of the alternating current supply.

8. The power factor correction converter according to claim 1, wherein the adjusted resistance of the series coupled resistor pair comprises a fixed resistor coupled in series with a transistor.

9. The power factor correction converter according to claim 8, including an integrated circuit controller and further comprising means for providing operating power for the integrated circuit controller under start-up conditions, wherein the means for providing is coupled to the transistor.

10. The power factor correction converter according to claim 9, wherein the means for providing comprises a diode, wherein the diode passes current from the rectified alternating current supply under start-up conditions and wherein the diode is reverse biased after start-up.

11. The power factor correction converter according to claim 10, where the means for providing comprises a switch wherein the switch passes current from the rectified current supply for providing power to the integrated circuit under start-up conditions and wherein the switch passes current from the rectified current supply to the intermediate node after start-up.

12. A method of performing power factor correction, comprising:

forming a first sensing signal representative of an input current received from an alternating-current supply;

forming a second sensing signal representative of an input voltage received from the supply;

equalizing the first and second sensing signals in a first feedback loop so as to maintain the input current in phase with the input voltage; and

adjusting a level of one of the first and second sensing signals in a second feedback loop so as to regulate an output voltage.

13. The method according to claim 12, where said equalizing comprises modulating a power switch coupled to receive the input current.

14. The method according to claim 13, wherein said equalizing further comprises integrating a signal representative of a difference between the first and second sensing signals.

15. The method according to claim 14, wherein said equalizing further comprises forming the signal representative of the difference between the first and second sensing signals at a virtual ground node.

16. The method according to claim 14, wherein said equalizing further comprises comparing the integrated signal to a periodic ramp signal and wherein a duty cycle of the switch is controlled by results of said comparing.

17. The method according to claim 12, wherein said adjusting comprises modulating a resistance value.

18. The method according to claim 17, wherein a current passing through the resistance value contributes to one of the first or second sensing signals.

19. The method according to claim 17, wherein said modulating comprises:

forming an error signal representative of the output voltage; and

controlling a transistor based upon a level of the error signal.

20. A method of performing power factor correction, comprising:

forming a first sensing signal representative of an input current received from a alternating-current supply;

forming a second sensing signal representative of an input voltage received from the supply;

forming a difference signal representative of a difference between the first sensing signal and the second sensing signal; and

forming a switch control signal in response to the difference signal for modulating the input current so as to maintain the input current in phase with the input voltage.

21. The method according to claim 20, further comprising disabling the switch control signal upon an output voltage reaching a first predetermined level and enabling the switch control signal upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level.

22. The method according to claim 21, further comprising integrating the difference signal thereby forming an integrated signal.

23. The method according to claim 22, further comprising:

comparing the integrated signal to a periodic ramp signal; and

forming the switch control signal in response to said comparing.

24. The method according to claim 23 wherein the periodic ramp signal has a fixed amplitude.

25. The method according to claim 24 wherein the periodic ramp signal has a varying amplitude that is representative of a level of the alternating current supply.

26. A controller for power factor correction converter, comprising:

switch modulation circuitry for modulating an input current received from an alternating-current supply so as to form an output voltage across an energy storage element;

output voltage regulating circuitry coupled to the switch modulation circuitry for disabling switching upon the output voltage reaching a first predetermined level and for enabling switching upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level; and

input voltage and current sensing circuitry coupled to the switch modulation circuitry for maintaining the input current in phase with the input voltage in a feedback loop, wherein the input voltage and current sensing circuitry receives a control signal formed at a virtual ground node, the control signal being representative of a difference between the input current and the input voltage.

27. The controller according to claim 26, further comprising an integrator coupled to receive the control signal formed at the virtual ground node.

28. The controller according to claim 27, further comprising a comparator for comparing an integrated signal formed by the integrator to a periodic ramp signal and for generating the switch control signal in response to results of the comparison.

29. The controller according to claim 28, wherein the controller is implemented as an integrated circuit having no more than eight pins.

30. The controller according to claim 29, wherein the controller includes means for disabling switching in the event of an over-current condition.

31. A controller for power factor correction converter, comprising:

switch modulation circuitry for modulating an input current received from an alternating-current supply so as to form an output voltage across an energy storage element;

input voltage and current sensing circuitry coupled to the switch modulation circuitry for maintaining the input current in phase with the input voltage in a feedback loop, wherein the input voltage and current sensing circuitry forms a first sensing signal representative of an input current received from a alternating-current supply, a second sensing signal representative of an input voltage received from the supply and a difference signal representative of a difference between the first sensing signal and the second sensing signal; and

output voltage regulating circuitry coupled to the switch modulation circuitry for forming an error signal representative of the output voltage and for adjusting a level of one of the first and second sensing signals in response to the error signal.

32. The controller according to claim 31, further comprising an integrator coupled to receive the difference signal.

33. The controller according to claim 32, further comprising a comparator for comparing an integrated signal formed by the integrator for a periodic ramp signal and for generating the switch control signal in response to results of the comparison.

34. The controller according to claim 33, wherein the controller is implemented as an integrated circuit having no more than eight pins.

35. The controller according to claim 34, wherein the output voltage regulating circuitry comprises means for disabling switching upon the output voltage reaching a first predetermined level and for enabling switching upon the output voltage falling to a second predetermined level, wherein the second predetermined level is lower than the first predetermined level.

36. The controller according to claim 34, wherein the controller includes means for disabling switching in the event of an over-current condition.