Power management in energy buffered building control unit

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 at least a portion of the energy stored in the capacitive storage element, the DC regulator providing a regulated electrical power;
• a rechargeable battery;
• 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;
• and
• a power management circuit, wherein the battery-charging/discharging circuit comprises a programmable input current limit that is set by the power management circuit.

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 at least a portion of 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, 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.

A method for operating a thermostat 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;
• measuring, using a voltage-measurement circuit, 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;
• 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;
• receiving, using a DC regulator, the energy stored in the capacitive element and regulating the 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.

A method for operating a thermostat further 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 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;
• selectively charging or discharging, using a battery-charging/discharging circuit, the rechargeable battery based at least in part on electrical load power;
• and
• setting, using a power management circuit, a programmable input current limit of the battery-charging/discharging circuit.

A method for operating a thermostat 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 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, 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.