Power factor correction using current sensing on an output

• US 7,616,455 B2
• Filed: 01/13/2006
• Issued: 11/10/2009
• Est. Priority Date: 12/09/2005
• Status: Expired due to Fees

• Current Assignee: Delta-Q Technologies Corp. (ZAPI S.p.A.)
• Original Assignee: Delta-Q Technologies Corp. (ZAPI S.p.A.)
• Inventors: MacCallum, Haakon, Cameron, Robert Fraser
• Primary Examiner(s): Patel; Rajnikant B
• Application Number:
  US11/331,067
• Publication Number:
  US 20070133233A1
• Time in Patent Office: 1,397 Days
• Field of Search: 323282-286, 323/222, 323/268, 323/271, 323/272, 323258-259, 323/262, 363/65, 363/40, 363/41, 363/89, 363/49, 363/39, 363/74, 363/124, 363 84- 85, 363/127, 363/125, 307 64- 66, 307/86, 307/87, 361/58, 361/64, 361/103
• US Class Current: 363/16
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• 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 method and apparatus for circuit conditioning, such as for providing power factor correction, is provided, using existing or minimal additional circuitry, at minimal or no additional cost to the manufacture of the circuit. The circuit conditioning is implemented by controlling an output side of the circuit based on a value sensed on the output side of the circuit and a relationship between the output side and an input side of the circuit.

Claims

1. A power convertor performing power factor correction comprising:

a power conversion stage having an input side and an output side electrically isolated from each other across a boundary of isolation; and

a control stage connected to said output side, said control stage comprising;

a sensor for measuring an output electrical parameter of said output side; and

a controller connected to said sensor and to said output side of said power conversion stage,

said controller having accessibly stored a known relationship between said output electrical parameter and a corresponding input electrical parameter of said input side,

said controller being operationally configured to generate a reference waveform indicative of a desired waveform for said output electrical parameter that achieves a desired waveform for said input electrical parameter based on said stored known relationship,

said controller being further operationally configured to receive from said sensor a value indicative of said output electrical parameter, to generate a control signal based on a comparison of said value with said reference waveform, and to send said control signal back to said power conversion stage;

wherein said power conversion stage is operationally configured to use said control signal received from said controller to modify said output electrical parameter and thereby condition said input electrical parameter and provide power factor correction based on said stored known relationship without measuring said input electrical parameter and using only parameters measured on said output side.

2. The power convertor of claim 1 included in a power supply wherein said input electrical parameter is an AC signal, said output electrical parameter is a DC signal, and said electrical isolation is galvanic isolation.

3. The power convertor of claim 1 wherein said reference waveform is a function of said desired waveform of said input electrical parameter and an input-to-output transfer function of said circuit.

4. The power convertor of claim 1 further comprising a zero crossing detection circuit for indicating to said controller, when said input electrical parameter has a value of zero.

5. The power convertor of claim 1 wherein said control signal is a pulse width modulated (PWM) signal, said control signal being varied by adjusting the duty cycle of said PWM signal.

6. The power convertor of claim 1 wherein said controller is implemented using one of an integrated circuit (IC), digital signal processor (DSP), and software.

7. The power convertor of claim 2 wherein said power supply operates in a continuous current mode.

8. The power convertor of claim 2 wherein said input and output electrical parameters are one of current and voltage.

9. The power convertor of claim 2 utilizing a high frequency switching topology including one of a Clark, current-fed push-pull, and flyback topology.

16. A power supply comprising the power convertor of claim 1.

17. A battery charger comprising the power convertor of claim 1.

10. A method for performing power factor correction in a power converter comprising a power conversion stage having an input side and an output side electrically isolated from each other across a boundary of isolation, said method comprising the steps of:

providing a control stage for said power converter on said output side, said control stage comprising a sensor for measuring an output electrical parameter of said output side and a controller connected to said sensor and to said output side of said power conversion stage;

storing for said controller, a known relationship between said output electrical parameter and a corresponding input electrical parameter of said input side;

generating a reference waveform indicative of a desired waveform for said output electrical parameter that achieves a desired waveform for said input electrical parameter based on said stored known relationship;

receiving from said sensor, a value indicative of said output electrical parameter;

generating a control signal based on a comparison of said value with said reference waveform;

sending said control signal back to said power conversion stage to modify said output electrical parameter; and

said power conversion stage using said control signal to modify said output electrical parameter and thereby condition said input electrical parameter and provide power factor correction based on said known relationship without measuring said corresponding input electrical parameter and using only parameters measured on said output side.

11. The method of claim 10 used in a power supply wherein said input electrical parameter is measured from an AC signal, said output electrical parameter is measured from a DC signal, and said electrical isolation is galvanic isolation.

12. The method of claim 10 wherein said reference waveform is a function of said desired waveform of said input electrical parameter and an input-to-output transfer function of said circuit.

13. The method of claim 10 further comprising the step of detecting when said input electrical parameter has a value of zero using a zero crossing detection circuit.

14. The method of claim 10 wherein said control signal is a pulse width modulated (PWM) signal, and further comprising the step of adjusting the duty cycle of said PWM signal when generating said control signal and using a variation of said duty cycle to control said output electrical parameter.

15. The method of claim 11 wherein said power supply operates in a continuous current mode.