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PFC apparatus for a converter operating in the borderline conduction mode

Imported: 23 Feb '17 | Published: 22 Oct '02

Shmuel Ben-Yaakov

USPTO - Utility Patents

Abstract

Power factor correction apparatus, for a switching power supply fed by an array of rectifying diodes and consisting of at least an input inductor, a contact of which is connected in series with a contact of the array, and of a power switch connected between the other contact of the array and the other contact of the input inductor that comprises circuitry for identifying, in each cycle determined by the switching frequency of the power supply, whenever the instantaneous value of the current through the inductor reaches a minimal value; circuitry for switching the power switch to its conducting state in response to the minimal current through the inductor; circuitry for reflecting the current flowing through the inductor by a measurable or simulated parameter; and circuitry for providing indication, in each cycle, by using the parameter, the indication being related to the timing until the peak value of the current, that corresponds to a specific load, has been essentially reached, or to the time from the moment that the current reaches the minimal value until the timing, and for switching the power switch to its non-conducting state in response to the indication.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other characteristics and advantages of the invention will be better understood through the following illustrative and non-limitative detailed description of preferred embodiments thereof, with reference to the appended drawings, wherein:

FIG. 1 illustrates a PWM Boost converter (prior art);

FIG. 2 illustrates exemplary Inductor current in Continuous Conduction Mode (CCM) for the converter illustrated in FIG. 1;

FIG. 3 illustrates exemplary Inductor current in Discontinuous Conduction Mode (DCM) for the converter illustrated in FIG. 1;

FIG. 4 illustrates exemplary Inductor current in Borderline Conduction Mode (BCM) for the converter illustrated in FIG. 1;

FIG. 5 illustrates a BCM APFC converter (prior art);

FIG. 6 illustrates a typical construction of an APFC converter (prior art);

FIG. 7 illustrates one block embodiment of a APFC controller (prior art);

FIG. 8 illustrates an APFC controller with no sensing of input voltage (prior art);

FIG. 9 illustrates a general layout and functioning of the BCM APFC controller, according to a preferred embodiment of the invention;

FIG. 10 illustrates exemplary control waveforms for the exemplary controller illustrated in FIG. 9;

FIG. 11 illustrates the general layout and functioning of one possible embodiment in which ‘k’ is a variable, according to one embodiment of the invention;

FIG. 12 illustrates the general layout and functioning of another possible embodiment in which the I

1 is a variable, according to one embodiment of the invention;

FIG. 13 illustrates exemplary realization of a circuit in which I

1 is a variable in accordance with the general layout illustrated in FIG. 12;

FIG. 14 illustrates exemplary realization of a circuit in which ‘k’ is a variable in accordance with the general layout illustrated in FIG. 11;

FIG. 15 illustrates a general layout and functioning, showing ‘End of T

OFF’ ‘pick-up’ from inductor voltage, according to another embodiment of the invention;

FIG. 16 illustrates a general layout and functioning, showing ‘End of T

OFF’ ‘pick-up’ from power transistor voltage, according to still another embodiment of the invention;

FIG. 17 illustrates a first general layout and functioning according to which the CCM APFC is implemented without sensing the input voltage, according to still another embodiment of the invention;

FIG. 18 illustrates a second general layout and functioning according to which the CCM APFC is implemented without sensing the input voltage, according to still another embodiment of the invention;

FIG. 19 illustrates a general functioning and layout of a digital APFC controller, according to one embodiment of the invention;

FIG. 20 illustrates a general functioning and layout of a ‘microprocessor-based’ APFC controller, according to another embodiment of the invention;

FIG. 21 illustrates a general functioning and layout of a ‘counter-based’ APFC controller, according to still another embodiment of the invention;

FIG. 22 illustrates a practical example of a ‘five-pin’ electronic module for implementing APFC circuit in BCM mode, according to a preferred embodiment of the invention;

FIG. 23 illustrates a simulated boost inductor (Lin) current and capacitor (Cc) voltage for the exemplary boost converter illustrated in FIG. 9;

FIG. 24 illustrates a simulated input voltage, input current and average input current for the exemplary boost converter illustrated in FIG. 9, and in accordance with the controlling signal depicted in FIG. 23;

FIG. 25 illustrates a ‘five-pin’ modular implementation of an APFC system, the module of which detailed circuitry is depicted in FIG. 22, according to one embodiment of the invention; and

FIG. 26 illustrates microelectronics unit implementation, according to another embodiment of the invention.

Claims

1. A power factor correction apparatus, for a switching power supply fed by an array of rectifying diodes and consisting of at least an input inductor, a contact of which is connected in series with a contact of said array, and of a power switch connected between the other contact of said array and the other contact of said input inductor, comprising:

2. Apparatus according to claim 1, further comprising:

3. Apparatus according to claim 1, in which the minimal value is essentially zero.

4. Apparatus according to claim 2, in which the deviation results from changes in the load.

5. Apparatus according to claim 2, in which the deviation results from changes in the power line voltage.

6. Apparatus according to claim 1, in which the circuitry for reflecting the current flowing through said inductor comprises:

7. Apparatus according to claim 1, comprising:

8. A power factor controller according to claim 7, in which said timing circuitry comprises:

9. A power factor controller according to claim 7, in which said driving circuit comprises a flip-flop, coupled to said timing circuit, that generates switching signal from the intermediate signal, for switching the first controllable switch.

10. A power factor controller according to claim 7, in which said first controllable current source is controlled by a voltage being a representative of the output voltage of the converter that is controlled.

11. A power factor controller according to claim 7, in which said second controllable current source is controlled by a voltage being a representative of the output voltage of the converter being controlled.

12. A power factor controller according to claim 7, in which said timing circuitry comprises a capacitor, coupled to the second switch, to said second controllable current source and to one input of an amplifier, said capacitor being charged whenever said second switch is closed and discharged whenever said second switch is open, the voltage of said capacitor being the intermediate signal and compared to a reference voltage coupled to a second input of said amplifier of which output is coupled to the flip-flop.

13. A power factor controller according to claim 7, in which said timing circuitry comprises:

14. A power factor controller according to claim 7, in which the timing circuitry further comprises a first oscillator having a constant frequency, for allowing to initialize/excite the operation of the converter and/or to resume normal operation, said first oscillator being inoperative in normal operation of said converter.

15. A power factor controller according to claim 7, in which the timing circuitry further comprises a second oscillator having a constant frequency, for allowing to operate the converter at constant frequency, said frequency being adjusted so as to maintain the input current of the converter above zero.

16. A power factor controller according to claim 14, in which the first oscillator and the second oscillator are the same oscillator, further comprising means for programming and/or for configuring and/or for switching said oscillator.

17. A power factor controller according to claim 7, in which the first current source adjusts a rate of decline of the intermediate signal and the second current source adjusts a rate of rise of the intermediate signal, said second controllable current source being greater in magnitude in comparison with said first controllable current source.

18. A power factor controller according to claim 7, in which the zero value input current of the converter is sensed by means of an analog comparator.

19. A power factor controller according to claim 7, in which the zero value input current of the converter is sensed by digital means.

20. A power factor controller according to claim 7, in which the zero value input current of the converter is sensed by a second inductor, being inductively coupled to the first inductor, said first inductor induces voltage on said second inductor.

21. A power factor controller according to claim 8, in which the control circuit comprises:

22. A power factor controller according to claim 13, in which the control circuit components are contained in a module that comprises five external contacts.

23. A power factor controller according to claim 13, in which the control circuit components are contained in an integrated circuit (IC).

24. A power factor controller according to claim 22, in which the input current sensing resistor and/or the output diode and/or the power switch are contained in, or being external to, a module that comprises five external contacts and/or to an integrated circuit (IC).

25. A power factor controller according to claim 15, in which the first oscillator and the second oscillator are the same oscillator, further comprising means for programming and/or for configuring and/or for switching said oscillator.

26. A power factor controller according to claim 21, in which the control circuit components are contained in a module that comprises five external contacts.

27. A power factor controller according to claim 26, in which the input current sensing resistor and/or the output diode and/or the power switch are contained in, or being external to, a module that comprises five external contacts and/or to an integrated circuit (IC).

28. A power factor controller according to claim 21, in which the control circuit components are contained in an integrated circuit (IC).

29. A power factor controller according to claim 28, in which the input current sensing resistor and/or the output diode and/or the power switch are contained in, or being external to, a module that comprises five external contacts and/or to an integrated circuit (IC).

30. A power factor controller according to claim 23, in which the input current sensing resistor and/or the output diode and/or the power switch are contained in, or being external to, a module that comprises five external contacts and/or to an integrated circuit (IC).