Power management in single circuit HVAC systems and in multiple circuit HVAC systems
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 operative 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 thermostat includes circuitry and methods for maximizing efficiency of energy harvested from the HVAC system connected to the thermostat, and depending on which system is connected to the thermostat, different power schemes can be implemented in order to obtain power from the HVAC system.
1. A thermostat for use in connection with a HVAC (heating, ventilation, and air conditioning) system, the HVAC system having a single circuit system, a multiple circuit system, or a common wire system, the thermostat comprising:
insertion sensing circuitry operative to provide insertion sensing signals indicative of a wiring scheme associated with the HVAC system being connected to the thermostat; and
control circuitry operative to:
receive the insertion sensing signals;
determine the wiring scheme based on the received insertion sensing signals; and
engage in single circuit power stealing, multi-circuit power stealing, or common wire power utilization for obtaining power from the HVAC system based on the determined wiring scheme, wherein:
the single circuit power stealing is characterized by using both active and inactive power stealing from a single HVAC control wire;
the multi-circuit power stealing is characterized by only using inactive power stealing on a non-enabled circuit within the multiple circuit system; or
the common wire system is characterized by using neither active power stealing nor inactive power stealing,
wherein active power stealing is characterized by momentarily opening a closed contact during an enabled phase of the single circuit system.
2. The thermostat of claim 1 , wherein the active power stealing is characterized in harvesting power from the HVAC system while it is engaged in an active HVAC function.
3. The thermostat of claim 1 , further comprising a switching circuit for controlling a HVAC function, wherein a closed switching circuit activates the HVAC function, wherein the active power stealing is performed during times when the HVAC function is active, wherein during active power stealing, the switching circuit opens for a time interval, wherein:
power is harvested from the HVAC system during the time interval; and
the time interval is short enough that the HVAC function remains active without interruption during the time interval.
4. The thermostat according to claim 1 , wherein the contact is closed during a majority of each duty cycle when the single circuit system is in the enabled phase.
5. The thermostat of claim 1 , further comprising:
wireless communications circuitry for communicating with an external server; and
an electronic display.
6. The thermostat of claim 5 , wherein power drawn by the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, is greater than an amount of power obtained by power stealing.
7. The thermostat of claim 6 , further comprising:
a battery that supplies power to the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, wherein power supplied by the battery makes up for a deficiency in the power obtained by power stealing.
8. A thermostat for use in connection with a HVAC (heating, ventilation, and air conditioning) system, the HVAC system having a single circuit system, a multiple circuit system, or a common wire system, the thermostat comprising:
insertion sensing circuitry operative to provide insertion sensing signals indicative of a wiring scheme associated with the HVAC system being connected to the thermostat; and
control circuitry operative to:
receive the insertion sensing signals;
determine the wiring scheme based on the received insertion sensing signals; and
engage in single circuit power stealing, multi-circuit power stealing, or common wire power utilization for obtaining power from the HVAC system based on the determined wiring scheme, wherein:
the single circuit power stealing is characterized by using both active and inactive power stealing from a single HVAC control wire;
the multi-circuit power stealing is characterized by only using inactive power stealing on a non-enabled circuit within the multiple circuit system; or
the common wire system is characterized by using neither active power stealing nor inactive power stealing,
wherein active power stealing is characterized by receiving power from an enabled HVAC relay circuit in a manner that does not untrip the enabled HVAC relay circuit.
9. The thermostat of claim 8 , further comprising:
wireless communications circuitry for communicating with an external server; and
an electronic display.
10. The thermostat of claim 9 , wherein power drawn by the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, is greater than an amount of power obtained by power stealing.
11. The thermostat of claim 10 , further comprising:
a battery that supplies power to the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, wherein power supplied by the battery makes up for a deficiency in the power obtained by power stealing.
12. A thermostat for use in connection with a HVAC (heating, ventilation, and air conditioning) system, the HVAC system having a single circuit system, a multiple circuit system, or a common wire system, the thermostat comprising:
insertion sensing circuitry operative to provide insertion sensing signals indicative of a wiring scheme associated with the HVAC system being connected to the thermostat; and
control circuitry operative to:
receive the insertion sensing signals;
determine the wiring scheme based on the received insertion sensing signals; and
engage in single circuit power stealing, multi-circuit power stealing, or common wire power utilization for obtaining power from the HVAC system based on the determined wiring scheme, wherein:
the single circuit power stealing is characterized by using both active and inactive power stealing from a single HVAC control wire;
the multi-circuit power stealing is characterized by only using inactive power stealing on a non-enabled circuit within the multiple circuit system; or
the common wire system is characterized by using neither active power stealing nor inactive power stealing,
wherein inactive power stealing is characterized by receiving power from a non-enabled HVAC relay circuit in a manner that does not trip the non-enabled HVAC relay circuit.
13. The thermostat of claim 12 , further comprising:
wireless communications circuitry for communicating with an external server; and
an electronic display.
14. The thermostat of claim 13 , wherein power drawn by the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, is greater than an amount of power obtained by power stealing.
15. The thermostat of claim 14 , further comprising:
a battery that supplies power to the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, wherein power supplied by the battery makes up for a deficiency in the power obtained by power stealing.
16. A thermostat for use in connection with a HVAC (heating, ventilation, and air conditioning) system, the HVAC system having a single circuit system, a multiple circuit system, or a common wire system, the thermostat comprising:
insertion sensing circuitry operative to provide insertion sensing signals indicative of a wiring scheme associated with the HVAC system being connected to the thermostat; and
control circuitry operative to:
receive the insertion sensing signals;
determine the wiring scheme based on the received insertion sensing signals; and
engage in single circuit power stealing, multi-circuit power stealing, or common wire power utilization for obtaining power from the HVAC system based on the determined wiring scheme, wherein:
the single circuit power stealing is characterized by using both active and inactive power stealing from a single HVAC control wire, wherein active power stealing is characterized in harvesting power from the HVAC system by fast switching a transistor;
the multi-circuit power stealing is characterized by only using inactive power stealing on a non-enabled circuit within the multiple circuit system, wherein inactive power stealing is characterized in harvesting power from the HVAC system by not fast switching the transistor; or
the common wire system is characterized by using neither active power stealing nor inactive power stealing.
17. The thermostat of claim 16 , wherein an HVAC function is activated when the transistor is closed, wherein the active power stealing is performed during times when the HVAC function is active, wherein during active power stealing, the transistor opens for a time interval, wherein:
power is harvested from the HVAC system during the time interval; and
the time interval is short enough that the HVAC function remains active without interruption during the time interval.
18. The thermostat of claim 17 , wherein a length of the time interval is determined by:
monitoring a voltage associated with a charge level of a capacitive element;
beginning the time interval when the voltage is below a lower threshold;
charging the capacitive element during the time interval; and
ending the time interval when the voltage exceeds an upper threshold.
19. The thermostat of claim 16 , further comprising:
wireless communications circuitry for communicating with an external server; and
an electronic display.
20. The thermostat of claim 19 , wherein power drawn by the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, is greater than an amount of power obtained by power stealing.
21. The thermostat of claim 20 , further comprising:
a battery that supplies power to the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, wherein power supplied by the battery makes up for a deficiency in the power obtained by power stealing.
22. A thermostat for use in connection with a HVAC (heating, ventilation, and air conditioning) system, the HVAC system having a single circuit system, a multiple circuit system, or a common wire system, the thermostat comprising:
insertion sensing circuitry operative to provide insertion sensing signals indicative of a wiring scheme associated with the HVAC system being connected to the thermostat; and
control circuitry operative to:
receive the insertion sensing signals;
determine the wiring scheme based on the received insertion sensing signals; and
engage in single circuit power stealing, multi-circuit power stealing, or common wire power utilization for obtaining power from the HVAC system based on the determined wiring scheme, wherein:
the single circuit power stealing is characterized by using both active and inactive power stealing from a single HVAC control wire, wherein active power stealing is characterized in harvesting power from the HVAC system by duty cycling a field effect transistor;
the multi-circuit power stealing scheme is characterized by only using inactive power stealing on a non-enabled circuit within the multiple circuit system, wherein inactive power stealing is characterized in harvesting power from the HVAC system by not duty cycling switching the field effect transistor; or
the common wire system is characterized by using neither active power stealing nor inactive power stealing.
23. The thermostat of claim 22 , further comprising:
wireless communications circuitry for communicating with an external server; and
an electronic display.
24. The thermostat of claim 23 , wherein power drawn by the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, is greater than an amount of power obtained by power stealing.
25. The thermostat of claim 24 , further comprising:
a battery that supplies power to the control circuitry, the wireless communications circuitry, and the electronic display, when all of the control circuitry, the wireless communications circuitry, and the electronic display are active, wherein power supplied by the battery makes up for a deficiency in the power obtained by power stealing.