HVAC CONTROLLER
A controller for an environmental control system, e.g., an HVAC system, that includes a power circuit for providing power to some components of the controller across a variety of HVAC systems. The HVAC controller of this disclosure may include components with power stealing circuitry to run components. However, because the diversity of HVAC system loads and configurations, some power stealing circuitry may not function as desired to draw the power for operation in some systems. The universal AC power circuit included in the HVAC controller of this disclosure may provide power to components of the HVAC controller when the power stealing circuitry may be incompatible with certain HVAC systems. In this manner, the universal AC power circuit may allow the HVAC controller of this disclosure to be compatible with and operate to control a wide variety of environmental control systems.
1 - 20 . (canceled)
21 . An alternating current (AC) load switch circuit comprising:
a first power input terminal configured to receive AC power from a transformer;
a second power input terminal;
a power output terminal configured to connect to an HVAC load; and
processing circuitry configured to:
receive a first indication when the HVAC load is connected to the power output terminal;
receive a second indication when a voltage magnitude at the second power input terminal is above a threshold voltage;
output a drive signal to a power converter circuit in response to receiving the first indication and the second indication.
22 . The AC load switch circuit of claim 21 , wherein the AC load switch circuit is configured to control operation of the HVAC load based on commands from the processing circuitry.
23 . The AC load switch circuit of claim 21 , wherein the processing circuitry is configured to receive the indication of whether the voltage magnitude at the second power input terminal is above the threshold voltage based on a digital message.
24 . The AC load switch circuit of claim 21 , wherein the processing circuitry is further configured to, in response to determining that the voltage magnitude at the second power input terminal is greater than the threshold voltage, withhold the drive signal.
25 . The AC load switch circuit of claim 21 , wherein the AC load switch circuit further includes a power stealing circuit configured to charge an electrical power storage device connected to the second power input terminal.
26 . The AC load switch circuit of claim 21 , wherein the drive signal is a pulse modulated signal.
27 . The AC load switch circuit of claim 21 , wherein the AC load switch circuit is configured to control AC current provided to the HVAC load through the power output terminal.
28 . The AC load switch circuit of claim 27 , wherein, based upon a temperature falling below a temperature setpoint, the processing circuitry is configured to provide power to the HVAC load.
29 . The AC load switch circuit of claim 21 , further comprising:
load sensing circuitry configured to detect the HVAC load.
30 . The AC load switch circuit of claim 29 , wherein the load sensing circuitry provides data to the processing circuitry regarding the HVAC load.
31 . The AC load switch circuit of claim 21 , further comprising:
a logic side and a switch side; and
an isolation barrier isolating the logic side from the switch side.
32 . The AC load switch circuit of claim 21 , further comprising:
a power stealing circuit configured to siphon power from the HVAC load.
33 . The AC load switch circuit of claim 32 , wherein the power stealing circuit is configured to power the AC load switch circuit.
34 . The AC load switch circuit of claim 32 , wherein the processing circuitry is configured to turn off the power stealing circuit based on the HVAC load.
35 . A method comprising:
receiving alternating current (AC) electrical power at a first power input terminal;
receiving an electrical connection at a power output terminal;
charging an electrical power storage device using power from a load when the load is connected to the power output terminal;
determining a voltage level of the electrical power storage device in response to the load being connected to the power output terminal; and
outputting a drive signal to a power converter circuit if the voltage level is above a threshold voltage.
36 . The method of claim 35 , wherein the load is a heating, ventilation, and air conditioning (HVAC) load.
37 . The method of claim 35 , wherein the electrical power storage device is a capacitor.
38 . The method of claim 35 , further comprising:
turning off the charging of the electrical power storage device based on the load.
39 . The method of claim 35 , further comprising:
sensing, via load sensing circuitry, data about the load.
40 . The method of claim 35 , wherein the drive signal is a pulse modulated signal.