Adaptive power stealing thermostat
First Claim
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 harvested power being harvested by a power harvesting circuit including an energy-storage element and a current controller, the method comprising:
- operating the current controller of the power harvesting circuit at a predetermined first setting associated with a first power level of the power harvesting circuit and at a predetermined second setting associated with a second, higher power level of the power harvesting circuit;
making at least one first measurement corresponding to an amount of energy stored by the energy-storage element while said current controller is operated at said first setting;
making at least one second measurement corresponding to an amount of energy stored by the energy-storage element while said current controller is operated at said second setting;
determining that a difference between said at least one first measurement and said at least one second measurement is less than a first predetermined threshold; and
responsive to said determining that said difference between said at least one first measurement and said at least one second measurement is less than said first predetermined threshold, operating the current controller of the power harvesting circuit at a predetermined third setting associated with a third power level of the power harvesting circuit that is higher than said second level;
whereby an amount of power harvested from the HVAC triggering circuit by said thermostat is increased while at the same time a reduced likelihood of an inadvertent on or off switching of said HVAC function is maintained.
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Accused Products
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.
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Citations
15 Claims
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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 harvested power being harvested by a power harvesting circuit including an energy-storage element and a current controller, the method comprising:
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operating the current controller of the power harvesting circuit at a predetermined first setting associated with a first power level of the power harvesting circuit and at a predetermined second setting associated with a second, higher power level of the power harvesting circuit; making at least one first measurement corresponding to an amount of energy stored by the energy-storage element while said current controller is operated at said first setting; making at least one second measurement corresponding to an amount of energy stored by the energy-storage element while said current controller is operated at said second setting; determining that a difference between said at least one first measurement and said at least one second measurement is less than a first predetermined threshold; and responsive to said determining that said difference between said at least one first measurement and said at least one second measurement is less than said first predetermined threshold, operating the current controller of the power harvesting circuit at a predetermined third setting associated with a third power level of the power harvesting circuit that is higher than said second level; whereby an amount of power harvested from the HVAC triggering circuit by said thermostat is increased while at the same time a reduced likelihood of an inadvertent on or off switching of said HVAC function is maintained. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A thermostat comprising:
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an HVAC triggering circuit comprising a call switch to turn on and turn off an HVAC function; a power harvesting circuit comprising; a current controller configured to operate at; a predetermined first setting associated with a first power level of the power harvesting circuit; and a predetermined second setting associated with a second, higher power level of the power harvesting circuit; and an energy-storage element; a measurement circuit configured to; make at least one first measurement corresponding to an amount of energy stored by the energy-storage element while said current controller is operated at said first setting; and make at least one second measurement corresponding to an amount of energy stored by the energy-storage element while said current controller is operated at said second setting; and a processor programmed to; determine that a difference between said at least one first measurement and said at least one second measurement is less than a first predetermined threshold; and responsive to said determining that said difference between said at least one first measurement and said at least one second measurement is less than said first predetermined threshold, cause the current controller of the power harvesting circuit to operate at a predetermined third setting associated with a third power level of the power harvesting circuit that is higher than said second level; whereby an amount of power harvested from the HVAC triggering circuit by said thermostat is increased while at the same time a reduced likelihood of an inadvertent on or off switching of said HVAC function is maintained. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification