POWER MANAGEMENT IN ENERGY BUFFERED BUILDING CONTROL UNIT

• US 20140358295A1
• Filed: 06/06/2014
• Published: 12/04/2014
• Est. Priority Date: 02/24/2011
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Nest Labs Incorporated (Alphabet Inc.)
• Inventors: WARREN, DANIEL ADAM, FIENNES, HUGO, DUTRA, JONATHAN ALAN, BELL, DAVID, FADELL, ANTHONY MICHAEL, ROGERS, MATTHEW LEE, SMITH, IAN C., SATTERTHWAITE, EDWIN H. Jr., MUCIGNAT, ANDREA, PALMER, JOSEPH E., ERICKSON, GRANT M.
• Granted Patent: US 9,435,559 B2
• Time in Patent Office: Days
• US Class Current: 700/278
• 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 11/46 Improving electric energy efficiency or saving
• 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 11/66 Sleep mode
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2120/00 Control inputs relating to users or occupants
• CPC Class Codes: F24F 2120/14 Activity of occupants
• CPC Class Codes: G05B 2219/2614 HVAC, heating, ventillation, climate control
• CPC Class Codes: G05B 2219/2642 Domotique, domestic, home control, automation, smart house
• 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

Abstract

A thermostat includes a plurality of HVAC (heating, ventilation, and air conditioning) wire connectors for receiving a plurality of HVAC control wires corresponding to an HVAC system. The thermostat also includes a thermostat processing and control circuit configured to at least partially control the operation of the HVAC system and a powering circuit coupled to the HVAC wire connectors and configured to provide an electrical load power to the thermostat processing and control circuit. The powering circuit has a power extraction circuit configured to extract electrical power from one or more of the plurality of received HVAC control wires up to a first level of electrical power, a rechargeable battery, and a power control circuit. The power control circuit is configured to provide the electrical load power using power from the power extraction circuit and the rechargeable battery.

Claims

1-20. -20. (canceled)

21. A thermostat, comprising:

at least one Heating, Ventilation, and Air Conditioning (HVAC) wire connector configured to receive at least one wire from an HVAC system;

an AC-to-DC conversion circuit coupled to the at least one HVAC wire connector and configured to receive an AC signal from the HVAC system and convert the AC signal to a DC signal;

a capacitive element storing energy provided by the DC signal from the AC-to-DC conversion circuit;

a DC regulator receiving the energy stored in the capacitive storage element, the DC regulator providing a regulated electrical power;

a rechargeable battery; and

a battery-charging/discharging circuit coupled to the rechargeable battery and receiving the regulated electrical power from the DC regulator, the battery-charging/discharging circuit (i) providing an electrical load power to the thermostat, and (ii) selectively charging or discharging the rechargeable battery based at least in part on the electrical load power.

22. The thermostat of claim 21, further comprising:

a voltage-measurement circuit receiving a voltage level of the capacitive element, wherein the at least one HVAC wire connector comprises at least one call relay wire connector and at least one return wire connector;

a switch between the at least one call relay wire connector and the at least one return wire connector, the switch being opened or closed based at least in part on the voltage level of the capacitive element as measured by the voltage-measuring circuit.

23. The thermostat of claim 22, wherein:

when the voltage level of the capacitive element drops below a first threshold voltage and the switch is closed, the switch is opened; and

when the voltage level of the capacitive element rises above a second threshold voltage and the switch is open, the switch is closed, wherein the second threshold voltage is higher than the first threshold voltage.

24. The thermostat of claim 21, further comprising a power management circuit, wherein the battery-charging/discharging circuit comprises a programmable input current limit that is set by the power management circuit.

25. The thermostat of claim 24, wherein:

the power management circuit adjusts the programmable input current limit of the battery-charging/discharging circuit based on a voltage level of the capacitive element.

26. The thermostat of claim 25, wherein:

the power management circuit sets the programmable input current limit of the battery-charging/discharging circuit to a first current level;

the power management circuit measures the voltage level of the capacitive element with the programmable input current limit set to the first current level; and

the power management circuit adjusts the programmable input current limit to a second current level that is greater than or equal to the first current level if the voltage level of the capacitive element is above a first threshold voltage, and sets the programmable input current level to a third current level that is less than or equal to the first current level if the voltage level of the capacitive element is less than a second threshold voltage.

27. The thermostat of claim 26, wherein:

the first current level is approximately 20 mA;

the second current level is approximately 40 mA; and

the third current level is less than or equal to approximately 20 mA.

28. The thermostat of claim 21, wherein:

during a first time period in which the electrical load power required by the thermostat is less than the regulated electrical power, the battery-charging/discharging circuit supplies the electrical load power to the thermostat and charges the rechargeable battery, if needed, using the regulated electrical power; and

during a second time period in which the electrical load power required by the thermostat is greater than said regulated electrical power, the battery-charging/discharging circuit discharges the rechargeable battery and supplies the required electrical load power to the thermostat using a combination of the regulated electrical power and power from discharging the rechargeable battery.

29. The thermostat of claim 21, wherein:

the AC-to-DC conversion circuit comprises a diode bridge rectifier; and

the DC regulator comprises a buck regulator.

30. The thermostat of claim 21, further comprising:

a main processor and a display, each having a low-power usage state and a high-power usage state, wherein the processor and display are selectively operated such that a long-term average power used by the thermostat circuitry is less than said electrical load power; and

a backplate processor configured to operate in a low-power state, the backplate processor also configured to poll sensors in the system on an ongoing basis while allowing the main processor to operate in the low-power usage state, wherein the backplate processor is configured to cause the main processor to move from the low-power usage state to the high-power usage state.

31. A method comprising:

receiving, through at least one Heating, Ventilation, and Air Conditioning (HVAC) wire connector, an AC signal from an HVAC system;

converting, using an AC-to-DC conversion circuit coupled to the at least one HVAC wire connector, the AC signal to a DC signal;

storing energy provided by the DC signal in a capacitive element;

receiving, using a DC regulator, the energy stored in the capacitive element and regulating the first electrical energy to provide regulated electrical power;

providing, using a battery-charging/discharging circuit coupled to a rechargeable battery, an electrical load power to the thermostat; and

selectively charging or discharging, using a battery-charging/discharging circuit, the rechargeable battery based at least in part on electrical load power.

32. The method of claim 31, further comprising:

measuring, using a voltage-measurement circuit, a voltage level of the capacitive elements, wherein the at least one HVAC wire connector comprises at least one call relay wire connector and at least one return wire connector;

controlling a switch between the at least one call relay wire connector and the at least one return wire connector, the switch being opened or closed based at least in part on the voltage level of the capacitive element as measured by the voltage-measuring circuit.

33. The method of claim 32, wherein:

opening the switch when the voltage level of the capacitive element drops below a first threshold voltage and the switch is closed; and

closing the switch when the voltage level of the capacitive element rises above a second threshold voltage and the switch is open, wherein the second threshold voltage is higher than the first threshold voltage.

34. The method of claim 31, further comprising setting, using a power management circuit, a programmable input current limit of the battery-charging/discharging circuit.

35. The method of claim 34, further comprising

adjusting, using the power management circuit, the programmable input current limit of the battery-charging/discharging circuit based on a voltage level of the capacitive element.

36. The method of claim 35, wherein:

the power management circuit sets the programmable input current limit of the battery-charging/discharging circuit to a first current level;

the power management circuit measures the voltage level of the capacitive element with the programmable input current limit set to the first current level; and

the power management circuit adjusts the programmable input current limit to a second current level that is greater than or equal to the first current level if the voltage level of the capacitive element is above a first threshold voltage, and sets the programmable input current level to a third current level that is less than or equal to the first current level if the voltage level of the capacitive element is less than a second threshold voltage.

37. The method of claim 36, wherein:

the first current level is approximately 20 mA;

the second current level is approximately 40 mA; and

the third current level is less than or equal to approximately 20 mA.

38. The method of claim 31, wherein:

during a first time period in which the electrical load power required by the thermostat is less than the regulated electrical power, the battery-charging/discharging circuit supplies the electrical load power to the thermostat and charges the rechargeable battery, if needed, using the regulated electrical power; and

during a second time period in which the electrical load power required by the thermostat is greater than said regulated electrical power, the battery-charging/discharging circuit discharges the rechargeable battery and supplies the required electrical load power to the thermostat using a combination of the regulated electrical power and power from discharging the rechargeable battery.

39. The method of claim 31, wherein:

the AC-to-DC conversion circuit comprises a diode bridge rectifier; and

the DC regulator comprises a buck regulator.

40. The method of claim 31, wherein the thermostat comprises:

a main processor and a display, each having a low-power usage state and a high-power usage state, wherein the processor and display are selectively operated such that a long-term average power used by the thermostat circuitry is less than said electrical load power; and

a backplate processor configured to operate in a low-power state, the backplate processor also configured to poll sensors in the system on an ongoing basis while allowing the main processor to operate in the low-power usage state, wherein the backplate processor is configured to cause the main processor to move from the low-power usage state to the high-power usage state.