ADAPTIVE POWER STEALING THERMOSTAT

• US 20120199660A1
• Filed: 10/06/2011
• Published: 08/09/2012
• Est. Priority Date: 09/14/2010
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Nest Labs Incorporated (Alphabet Inc.)
• Inventors: WARREN, Daniel Adam, SATTERTHWAITE, Edwin H. Jr., PALMER, Joseph E., SMITH, Ian C.
• Granted Patent: US 9,261,287 B2
• Time in Patent Office: Days
• US Class Current: 236/1.C
• CPC Class Codes: B01D 46/0086 Filter condition indicators
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/32 Responding to malfunctions or emergencies
• CPC Class Codes: F24F 11/39 Monitoring filter performance
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/47 Responding to energy costs
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/56 Remote control
• CPC Class Codes: F24F 11/58 using Internet communication
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/89 Arrangement or mounting of control or safety devices
• CPC Class Codes: F24F 2110/00 Control inputs relating to air properties
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2120/10 Occupancy
• CPC Class Codes: F24F 2120/20 Feedback from users
• CPC Class Codes: F24F 2130/40 Noise
• CPC Class Codes: F24F 2140/00 Control inputs relating to system states
• CPC Class Codes: F24F 2140/60 : Energy consumption
• CPC Class Codes: G05B 13/0265 : the criterion being a learning criterion
• CPC Class Codes: G05B 15/02 : electric
• CPC Class Codes: G05D 23/19 : characterised by the use of electric means G05D23/1393 takes precedence
• CPC Class Codes: G05D 23/1902 : characterised by the use of a variable reference value
• CPC Class Codes: G05D 23/1917 : using digital means
• CPC Class Codes: H01R 9/2416 : Means for guiding or retaining wires or cables connected to terminal blocks
• CPC Class Codes: H04W 4/70 : Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: Y02B 10/20 : Solar thermal
• CPC Class Codes: Y02B 10/70 : Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
• CPC Class Codes: Y02D 30/70 : in wireless communication networks
• CPC Class Codes: Y10T 29/49826 : Assembling or joining

Abstract

An electronic thermostat and associated methods are disclosed for power stealing from an HVAC triggering circuit. The methods include making voltage measurements while controlling the amount of current drawn by the power stealing circuitry so as to determine a relationship that can be used to select how much current to draw during power stealing. Through the use of the described methods, the likelihood of inadvertent switching of the HVAC function (on or off) can be significantly reduced.

Claims

1. A method for harvesting power from an HVAC triggering circuit that includes a call switch to turn on and turn off an HVAC function, the harvested power being used by a thermostat connected to the HVAC triggering circuit, the method comprising:

making at least one measurement that is at least partially influenced by an amount of electrical current flowing through the call switch; and

controlling an amount of power the thermostat harvests from the HVAC triggering circuit based at least in part on the measurement so as to reduce a likelihood of inadvertently switching the HVAC function on or off.

2. A method according to claim 1 wherein the call switch is an electromechanical relay.

3. A method according to claim 1 wherein the call switch includes a solid-state component capable of measuring a voltage drop due to current through the call switch.

4. A method according to claim 1 further comprising making a second measurement that is least partially influenced by the amount of electrical current flowing through the call switch, wherein the amount of electrical current flowing through the call switch when the at least one measurement is made is different than the amount of electrical current flowing through the call switch and the second measurement is made.

5. A method according to claim 4 wherein the at least one measurement and the second measurement are voltage measurements made at a node internal to the thermostat.

6. A method according to claim 1 wherein the controlling the amount of power the thermostat harvests is automatically controlled at least in part using a microprocessor.

7. A method according to claim 1 wherein the controlling includes selecting one of two or more predetermined levels of current drawn by the thermostat.

8. A method according to claim 7 further comprising:

making a subsequent measurement that is at least partially influenced by the amount of electrical current flowing through the call switch; and

adjusting the amount of power the thermostat harvests from the HVAC triggering circuit based at least in part on the subsequent measurement.

9. A method according to claim 1 further comprising making a plurality of subsequent measurements that are at least partially influenced by the amount of electrical current flowing through the call switch, and wherein the controlling includes incrementally adjusting a level of current drawn by the thermostat based at least in part on the one or more of the subsequent measurements.

10. A method according to claim 1 wherein the controlling the amount of power the thermostat harvests occurs when the HVAC function is inactive.

11. A method according to claim 1 wherein the power harvesting causes a drop in voltage across the call switch, and said controlling the amount of power the thermostat harvests results in the drop in voltage across the call switch to be less than about 8V_RMS.

12. A method according to claim 11 wherein said controlling the amount of power the thermostat harvests results in the drop in voltage across the call switch to be less than about 6V_RMS.

13. A method according to claim 12 wherein said controlling the amount of power the thermostat harvests results in the drop in voltage across the call switch to be less than about 5.5V_RMS.

14. A method according to claim 1 wherein the controlling the amount of power the thermostat harvests occurs when the HVAC function is active.

15. A thermostat comprising a processing system and other components adapted and arranged to carry out a method according to claim 1.

16. A thermostat for harvesting power from an HVAC triggering circuit that includes a call switch to turn on and turn off an HVAC function, the thermostat comprising:

power stealing circuitry adapted and configured to harvest power from the HVAC triggering circuit;

voltage measurement circuitry adapted and configured to make at least one electrical measurement that is at least partially influenced by the amount of electrical current flowing through the call switch; and

processing and control circuitry adapted and configured to control an amount of power that the thermostat harvests from the HVAC triggering circuit based at least in part on the measurement so as to reduce a likelihood of inadvertently switching the HVAC function on or off.

17. A thermostat according to claim 16, wherein the processing and control circuitry controls the amount of power that the thermostat harvests by controlling an amount of current that the thermostat harvests from the HVAC triggering circuit.

18. A thermostat according to claim 17, wherein the processing and control circuitry is programmed to select from two or more predetermined current levels for power harvesting so as to reduce the likelihood of inadvertently switching the HVAC function on or off.

19. A thermostat according to claim 17 wherein the processing and control circuitry is adapted to incrementally adjust the amount of current that the thermostat harvests based at least in part on the electrical measurements made by the voltage measurement circuitry.

20. A thermostat according to claim 16 wherein the at least one voltage measurement is a voltage measurement made at a node internal to the thermostat.

21. A thermostat according to claim 16 wherein the processing and control circuitry controls the amount of power that the thermostat harvests from the HVAC triggering circuit such that the power harvesting causes a drop in voltage across the call switch that is less than about 8V_RMS.

22. A thermostat according to claim 21 wherein the processing and control circuitry controls the amount of power that the thermostat harvests from the HVAC triggering circuit such that the power harvesting causes a drop in voltage across the call switch that is less than about 6V_RMS.