Active power stealing
First Claim
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.
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Accused Products
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.
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Citations
18 Claims
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1. A thermostat comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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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. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification