POWER STEALING CIRCUITRY FOR A CONTROL DEVICE

• US 20100026379A1
• Filed: 07/29/2008
• Published: 02/04/2010
• Est. Priority Date: 07/29/2008
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Tousignant, Daniel, Simard, Pierre, Meilleur, Benoit
• Granted Patent: US 8,110,945 B2
• Time in Patent Office: Days
• US Class Current: 327/540
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 5/2573 with control circuit
• CPC Class Codes: H02M 7/04 by static converters
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output

Abstract

A power stealing circuit for stealing power to operate a control device is disclosed. In one illustrative embodiment, power may be periodically or intermittently diverted from a power source to a power stealing block. When power is diverted to the power stealing block, the power stealing block may steal power from the power source and store the stolen power on a storage device. The storage device may then provide operating power to a control device. In some embodiments, the power stealing block may include a first path for charging the storage device when a switch is ON, and a second path for charging the storage device when the switch is off. The switch may be switched OFF when, for example, when the voltage provided by the rectifier is greater than a threshold voltage, the voltage detected on the storage device is greater than a threshold value, and/or when a control signal from a controller disables the switch.

Claims

1. A control device for a load, comprising:

a storage device for storing charge;

a power stealing block including a first switch, the power stealing block for stealing power from a power source and storing the stolen power on the storage device, the power stealing block including a first path for charging the storage device when the first switch is ON, and a second path for charging the storage device when the first switch is off.

2. The control device of claim 1, wherein the first path has a lower impedance that the second path when the first switch is ON.

3. The control device of claim 2, wherein the second path has a lower impedance that the second path when the first switch is OFF.

4. The control device of claim 1, further comprising a second switch, wherein the second switch is provided in parallel with the power stealing block and switches power to the load from a power source, the control device periodically or intermittently switching the second switch ON and OFF.

5. The control device of claim 4, wherein the second switch is switched ON when the line voltage is larger than a threshold value.

6. The control device of claim 4, wherein the second switch is switched OFF when the line voltage is smaller than a threshold value.

7. The control device of claim 6 wherein, when the second switch is switched OFF, current is diverted from the power source to the power stealing block.

8. The control device of claim 1 further comprising a control block, wherein the control block provides a power stealing enable output signal coupled to the first switch to enable and/or disable the first switch.

9. The control device of claim 1 further comprising a discriminator that monitors a measure related to the voltage supplied to the power stealing block, and if the measure related to the voltage supplied to the power stealing block is larger than a threshold value, the discriminator disables the first switch.

10. The control device of claim 1 further comprising a voltage detector configured to detect a measure related to the voltage across the storage device, and if the measure related to the voltage across the storage device is larger than a threshold value, the voltage detector disables the first switch.

11. The control device of claim 1 further comprising:

a control block, wherein the control block provides a power stealing enable output signal coupled to the first switch to enable and/or disable the first switch;

a discriminator that monitors a measure related to the voltage supplied to the power stealing block, and if the measure related to the voltage supplied to the power stealing block is larger than a threshold value, the discriminator disables the first switch; and

a voltage detector configured to detect a measure related to the voltage across the storage device, and if the measure related to the voltage across the storage device is larger than a threshold value, the voltage detector disables the first switch.

12. The control device of claim 1 wherein the storage device includes a capacitor.

13. The control device of claim 1 wherein the storage device includes a rechargeable battery.

14. The control device of claim 1 wherein the first switch is a transistor.

15. The control device of claim 4 wherein the second switch is a Triac.

16. The control device of claim 1 wherein the second path includes one or more resistors.

17. A method of stealing power for a control device, the method comprising:

periodically or intermittently diverting power from a power source to a power stealing block;

when power is diverted to the power stealing block, charging a charge storage device via a first path if it is desirable to charge the charge storage device faster, and charging the charge storage device via a second path if it is desirable to charge the charge storage device slower;

providing operating power to the control device from the charge storage device.

18. The method of claim 17 wherein the charge storage device is charged via the second path if a voltage of the diverted power is above a threshold value.

19. The method of claim 17 wherein the charge storage device is charged via the second path if a voltage across the charge storage device is above a threshold value.

20. A circuit for stealing power from a load to provide power for a control device, comprising:

a storage device for storing charge for the control device;

a rectifier including a first terminal connected to an alternating current power supply, a second terminal connected to a load, and a third terminal providing a direct current signal;

a transistors for activating a first path from the third terminal of the rectifier to the storage device;

a bypass resistor in a second path from the third terminal of the rectifier to the storage device;

wherein current flows along the first path to the storage device when the transistor is ON, and current flows along the second path to the storage device when the transistor is off.

21. The circuit of claim 20 further comprising a discriminator configured to switch the transistor off when the voltage provided by the rectifier is greater than a threshold voltage.

22. The circuit of claim 21 further comprising a voltage detector configured to switch the transistor off when the voltage detected on the storage device is greater than a threshold value.

23. The circuit of claim 22 further comprising an enabler configured to switch the transistor off according to a control signal from a controller.