Monitoring and recoverable protection of thermostat switching circuitry

• US 9,935,455 B2
• Filed: 12/13/2013
• Issued: 04/03/2018
• Est. Priority Date: 09/21/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Warren, Daniel Adam, Conner, Brian J., Smith, Ian C.
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): McAndrew, Christopher
• Application Number:
  US14/106,544
• Publication Number:
  US 20140175181A1
• Time in Patent Office: 1,572 Days
• Field of Search: 324550
• CPC Class Codes: F24D 5/02 operating with discharge of hot air into the space or area to be heated
• CPC Class Codes: F24D 5/12 using heat pumps
• CPC Class Codes: G01R 31/74 Testing of fuses
• CPC Class Codes: G05D 23/19 characterised by the use of electric means G05D23/1393 takes precedence
• CPC Class Codes: G05D 23/1902 characterised by the use of a variable reference value
• CPC Class Codes: H01H 2300/03 Application domotique, e.g. for house automation, bus connected switches, sensors, loads or intelligent wiring
• CPC Class Codes: H01H 85/0241 Structural association of a fuse and another component or apparatus switches with built-in fuses H01H9/10, spark-gap arresters H01H85/44, transformers and inductances H01F27/402, capacitors H01G2/14, lamps H01K1/66, semiconductors H01L23/5256 or H01L23/62
• CPC Class Codes: H01H 85/32 Indicating lamp structurally associated with the protective device
• CPC Class Codes: H02H 7/20 for electronic equipment for converters H02H7/10; for electric measuring instruments G01R1/36; for dc voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08
• CPC Class Codes: H05B 1/0205 using a fusible material
• CPC Class Codes: Y02B 30/13 Hot air central heating systems using heat pumps
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/14 Protecting elements, switches, relays or circuit breakers

Abstract

A method of automated sensing of an electrical anomaly associated with a thermostat may include switching a switching circuit within the thermostat to an on state. The switching circuit may be configured to activate an HVAC function when switched to the on state. The method may also include monitoring one or more electrical properties associated with the switching circuit. The method may additionally include determining if an electrical anomaly is associated with the switching circuit based at least in part on the monitored one or more electrical properties. The method may further include switching the switching circuit to an off state if an electrical anomaly is detected.

Claims

1. A thermostat comprising:

a switching circuit configured to operate in an on state and an off state, the switching circuit further configured to activate an HVAC function when switched to the on state;

one or more processors; and

a fault-protected driver chip configured to;

monitor one or more electrical properties associated with the switching circuit;

receive an enable signal from the one or more processors to activate the HVAC function;

provide a drive signal to the switching circuit to cause the switching circuit to switch to the on state to activate the HVAC function;

determine if an electrical anomaly associated with the switching circuit is present based at least in part on the monitored one or more electrical properties, wherein the electrical anomaly comprises an over-current or over-voltage anomaly;

cause switching circuit to switch to the off state if an electrical anomaly is detected;

provide a fault signal to the one or more processors;

determine, while the switching circuit remains in the off state, if the electrical anomaly has been corrected; and

subsequent to a determination that the anomaly has been corrected, cause the switching circuit to switch to the on state.

2. A thermostat according to claim 1, wherein the switching circuit comprises a first Field Effect Transistor (FET).

3. A thermostat according to claim 2, wherein the monitored one or more electrical properties includes a voltage level of a node associated with a drain of the first FET.

4. A thermostat according to claim 2, wherein the switching circuit comprises a second FET that is switched on and off with the first FET.

5. A thermostat according to claim 1, wherein the one or more processors are further programmed to determine if the electrical anomaly is caused by an anomalous wiring condition.

6. A thermostat according to claim 5, further comprising a user interface, wherein the one or more processors are further programmed to display an error message on the user interface indicating the anomalous wiring condition.

7. A thermostat according to claim 1, wherein the fault-protected driver chip electrically isolates the one or more processors from a 24 VAC voltage line of an HVAC system.

8. A thermostat according to claim 1, wherein the fault-protected driver chip is powered by a differential clock signal from the one or more processors.

9. A thermostat according to claim 1, wherein the electrical anomaly comprises a voltage level surpassing a threshold voltage that indicates excessive current in the switching circuit.

10. A thermostat according to claim 1, wherein the one or more processors comprises a backplate microprocessor that communicates with a head unit microprocessor.

11. A thermostat according to claim 1, wherein the thermostat further comprises a wireless communication module configured to communicate with a cloud-based thermostat management server.