Circuit and associated method for reducing power consumption in an a power transformer

• US 20090154206A1
• Filed: 12/12/2007
• Published: 06/18/2009
• Est. Priority Date: 12/12/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Lum, Richard K.K., Fouquet, Julie Elizabeth, Baumgartner, Richard A.
• Granted Patent: US 7,852,645 B2
• Time in Patent Office: Days
• US Class Current: 363/84
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004
• CPC Class Codes: H02J 9/007 Detection of the absence of a load
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A method and circuit is provided for reducing power consumption in a power transformer, typically incorporated into an electrical or electronic device such as a consumer device. In an embodiment, a detection/isolation circuit is coupled to an input of a power transformer/rectifier via a switching device. The switching device can be, for example, a solid state relay. The detection/isolation circuit is configured to sense the occurrence of no-load conditions in the power transformer and responsively disengage the power transformer from a coupled source of power (e.g., wall outlet) via the coupled switching device.

Claims

1. A circuit for reducing power consumption in a power transformer during low-load and no-load conditions, the circuit comprising:

a first switching device coupled to an input of the power transformer, said switching device configured to disengage said power transformer from a power source upon detecting said no-load and low-load conditions on said power transformer;

a rectifier coupled to an output of said power transformer, said rectifier for rectifying an output voltage of said power transformer;

an energy storing device coupled in parallel to an output of said rectifier, said energy storing device for storing energy during a load condition and for providing energy during said low-load and no-load conditions;

a voltage sense module coupled to said energy storing device, for continuously monitoring a voltage on said energy storing device and for outputting a first control signal upon detecting a low voltage condition on said energy storing device;

a current sense module coupled to an output of said power transformer, said current sense module for detecting a load on said power transformer and for outputting a second control signal upon detecting said load condition;

a control circuit for receiving said first control signal from said voltage sense module and for receiving said second control signal from said current sense module and for outputting a close switch signal to said switching device in response to receiving said first and second control signals.

2. A circuit according to claim 1, further comprising a regulator module for regulating power distributed to said voltage sense module, said current sense module and said control circuit.

3. A circuit according to claim 1, further comprising a second switching device coupled to an output of said power transformer.

4. A circuit according to claim 3, wherein the first and second switching devices are selected from the group comprising:

optical switching devices, electromagnetic switching devices, power switching devices.

5. A circuit according to claim 4, wherein the power switching device is a solid state relay.

6. A circuit according to claim 3, wherein said first and second switching devices open and close substantially simultaneously.

7. A circuit according to claim 1, wherein said detection of said low voltage condition comprises detecting a voltage on said energy storing device being substantially equal to a pre-determined threshold voltage.

8. A circuit according to claim 1, wherein said capacitor is on the order of 1 farad.

9. A circuit according to claim 1, wherein said power transformer is an element of a consumer device.

10. A circuit according to claim 1, wherein said low-load condition is less than substantially 5 mW.

11. A circuit according to claim 1, wherein said current sense module further comprises a sensing resistor for detecting a load on said power transformer.

12. A method for reducing power consumption in a power transformer during low-load and no-load conditions, the method comprising:

(a) monitoring an output of said power transformer to identify a first transition from a load condition to one of a no-load or low-load condition on said power transformer;

(b) monitoring an output of said power transformer to identify a second transition from one of said no-load or low-load condition to said load condition;

(c) opening a switching device to disengage said power transformer from a power source upon identifying said first transition at said monitoring step (a);

(d) closing said first switching device to engage said power transformer to said power source upon identifying said second transition at said monitoring step (b); and

(e) continuously repeating said monitoring steps (a) and (b).

13. A method according to claim 12, further comprising:

(f) monitoring a voltage level of an energy storing device coupled to an output of said power transformer to identify a low voltage condition on said energy storing device; and

(g) losing said first switching device to engage said power transformer to said power source upon identifying said low voltage condition on said energy storing device.

14. A method according to claim 12, wherein said energy storing device is one of a super-capacitor or capacitor.

15. A method according to claim 12, further comprising a second switching device that is opened and closed in unison with said first switching device.

16. A method according to claim 15, wherein said second switching device is a solid state relay.

17. A method according to claim 12, wherein said monitoring step (a) further comprises detecting the presence of an output voltage across a sensing resistor at said power transformer output.

18. A method according to claim 12, wherein said monitoring step (c) further comprises detecting the absence of an output voltage across a sensing resistor at said power transformer output.

19. A method according to claim 12, wherein said energy storing device receives energy from said power transformer during periods when said first switching device is closed and distributes energy to monitoring and detection circuitry during periods when said first switching device is open.

20. A device having reduced power consumption during low-load and no-load conditions, the circuit comprising:

a rectifier for converting AC to DC power;

a power transformer coupled to said rectifier;

a power reduction circuit for reducing power consumption during said low-load and no-load conditions, the power reduction circuit comprising;

(a) a first switching device coupled to an input of the power transformer, said switching device configured to disengage said power transformer from a power source upon detecting said no-load and low-load conditions on said power transformer;

(b) an energy storing device coupled in parallel to an output of said power transformer, said energy storing device for storing energy during a load condition and for providing energy during said low-load and no-load conditions;

(c) a voltage sense module coupled to said capacitor, for continuously monitoring a voltage on said energy storing device and for outputting a first control signal upon detecting a low voltage condition on said energy storing device;

(d) a current sense module coupled to an output of said power transformer, said current sense module for detecting a load on said power transformer and for outputting a second control signal upon detecting said load condition; and

(e) a control circuit for receiving said first control signal from said voltage sense module and for receiving said second control signal from said current sense module and for outputting a close switch signal to said switching device in response to receiving said first and second control signals.

21. A device according to claim 20, further comprising a second switching device coupled to an output of said power transformer.

22. A device according to claim 21, wherein the first and second switching devices are solid state relays.

23. A device according to claim 20, further comprising a regulator module for regulating power distributed to said voltage sense module, said current sense module and said control circuit.

24. A device according to claim 20, wherein said detection of said low voltage condition comprises detecting a voltage on said energy storing device being substantially equal to a predetermined threshold voltage.

25. A device according to claim 20, wherein said device is a consumer device.