Active power stealing

• US 9,696,734 B2
• Filed: 04/30/2014
• Issued: 07/04/2017
• Est. Priority Date: 09/14/2010
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Warren, Daniel Adam, Fiennes, Hugo, Fadell, Anthony Michael, Rogers, Matthew Lee, Bell, David, Dutra, Jonathan Alan
• Primary Examiner(s): Walters, Ryan J
• Assistant Examiner(s): TRPISOVSKY, JOSEPH F
• Application Number:
  US14/266,474
• Publication Number:
  US 20140231530A1
• Time in Patent Office: 1,161 Days
• Field of Search: 236 1 C, 236 94, 700276
• 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

A thermostat and related methods are described for controlling one or more functions, such as heating and cooling in an HVAC. According to some embodiments the thermostat includes a switching circuit for controlling an HVAC function, where closing the switching circuit activates the HVAC function. The thermostat may also include power harvesting circuitry adapted and arranged to harvest power from the HVAC system, where during times when the HVAC function is active the switching circuit opens for a time interval. The power harvesting circuitry may harvest power from the HVAC system during the time interval, and the time interval may be short enough that the HVAC function remains activated without interruption during the time interval.

Claims

1. A thermostat comprising:

a switching circuit for controlling a Heating, Ventilation, and Air Conditioning (HVAC) function of an HVAC system, wherein closing the switching circuit activates the HVAC function; and

power harvesting circuitry adapted and arranged to harvest power from the HVAC system, wherein during times when the HVAC function is active, the switching circuit opens for a time interval, wherein the power harvesting circuitry;

monitors a voltage associated with a charge level of a capacitive element;

begins the time interval after the voltage is below a lower threshold;

harvests power from the HVAC system to charge the capacitive element during the time interval; and

ends the time interval after the voltage exceeds an upper threshold, wherein the time interval is short enough that the HVAC function remains activated without interruption during the time interval.

2. The thermostat of claim 1, further comprising:

a rechargeable battery; and

charging circuitry adapted and arranged to recharge the rechargeable battery using power harvested by the power harvesting circuitry.

3. The thermostat of claim 2, wherein the charging circuitry is adapted to charge the rechargeable battery such that longer cycle life is preferred over higher charge capacity.

4. The thermostat of claim 1, wherein the power harvesting circuitry is adapted and arranged to determine whether a common wire is available to the thermostat, and only harvest power from the HVAC system in cases where no common wire is available to the thermostat.

5. The thermostat of claim 1, wherein the power harvesting circuitry is further adapted and arranged to harvest power from the HVAC system during times when the HVAC function is inactive.

6. The thermostat of claim 1, wherein the power harvesting circuitry is adapted and arranged to automatically select the HVAC function from among one or more HVAC functions of the HVAC system.

7. The thermostat of claim 1, wherein during the time interval, the power harvesting circuitry charges one or more capacitive and/or magnetic elements to store electrical energy for use by the charging circuit and/or other operations in the thermostat.

8. The thermostat of claim 1, wherein the switching circuit comprises solid state switching components and circuitry adapted and arranged to quickly open and close.

9. The thermostat of claim 1, wherein the thermostat is adapted to control HVAC systems having more than one power transformer.

10. A method comprising:

closing a switching circuit for controlling a Heating, Ventilation, and Air Conditioning (HVAC) function of an HVAC system, wherein closing the switching circuit activates the HVAC function;

monitoring a voltage associated with a charge level of a capacitive element;

opening the switching circuit for a time interval, wherein the time interval begins after the voltage is below a lower threshold;

harvesting power from the HVAC system to charge the capacitive element during the time interval by power harvesting circuitry; and

ending the time interval after the voltage exceeds an upper threshold, wherein the time interval is short enough that the HVAC function remains activated without interruption during the time interval.

11. The method of claim 10, further comprising:

charging, using charging circuitry, a rechargeable battery using power harvested by the power harvesting circuitry.

12. The method of claim 11, wherein the charging circuitry is adapted to charge the rechargeable battery such that longer cycle life is preferred over higher charge capacity.

13. The method of claim 10, wherein the power harvesting circuitry is adapted and arranged to determine whether a common wire is available to the thermostat, and only harvest power from the HVAC system in cases where no common wire is available to the thermostat.

14. The method of claim 10, wherein the power harvesting circuitry is further adapted and arranged to harvest power from the HVAC system during times when the HVAC function is inactive.

15. The method of claim 10, wherein the power harvesting circuitry is adapted and arranged to automatically select the HVAC function from among one or more HVAC functions of the HVAC system.

16. The method of claim 10, wherein during the time interval, the power harvesting circuitry charges one or more capacitive and/or magnetic elements to store electrical energy for use by the charging circuit and/or other operations in the thermostat.

17. The method of claim 10, wherein the switching circuit comprises solid state switching components and circuitry adapted and arranged to quickly open and close.

18. The method of claim 10, wherein the thermostat is adapted to control HVAC systems having more than one power transformer.