Thermostat with heat rise compensation based on wireless data transmission

Patent metadata

Field	Value
Publication number	US-10443876-B2
Application number	US-201816138516-A
Country	US
Kind code	B2
Filing date	Sep 21, 2018
Priority date	Feb 6, 2015
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

A HVAC controller located within a building zone includes a housing, a wireless radio, a controller monitor, a temperature sensor, and a temperature compensation module. The wireless radio is contained within the housing and is configured to transmit data via a wireless HVAC network. The controller monitor is configured to detect wireless activity of the wireless radio, the wireless activity generating heat inside the housing and causing a temperature inside the housing to exceed a temperature of the building zone outside the housing. The temperature sensor is configured to measure the temperature inside the housing. The temperature compensation module is configured to determine a wireless heat rise resulting from the wireless activity, to calculate a temperature offset based on the wireless heat rise, and to determine the temperature of the building zone outside the housing by subtracting the temperature offset from the temperature measured inside the housing.

First claim

What is claimed is:

1. A method of heat rise compensation for a controller comprising a wireless radio circuit located within a housing of the controller, wherein wireless activity of the wireless radio circuit generates heat inside the housing of the controller causing a first temperature measured inside the housing to exceed a second temperature of a building zone outside the housing, the method comprising:
detecting, by a processing circuit, the wireless activity of the wireless radio circuit;
determining, by the processing circuit, a wireless heat rise resulting from the wireless activity;
calculating, by the processing circuit, a temperature offset based on the wireless heat rise as a function of both a wireless offset and the wireless heat rise resulting from the wireless activity, wherein the wireless offset represents a baseline amount of heat generated by the wireless radio circuit independent from the wireless heat rise resulting from the wireless activity; and
determining, by the processing circuit, the second temperature of the building zone outside the housing by subtracting the temperature offset from the first temperature measured inside the housing.

2. The method of claim 1 , further comprising generating, by the processing circuit, an actual wireless data value representing an actual amount of wireless data transmitted by the wireless radio circuit over a time period;
wherein determining, by the processing circuit, the wireless heat rise resulting from the wireless activity comprises determining the wireless heat rise resulting from the wireless activity as a function of the actual wireless data value.

3. The method of claim 2 , wherein determining, by the processing circuit, the wireless heat rise resulting from the wireless activity further comprises:
identifying a maximum wireless data value representing a maximum amount of wireless data capable of being transmitted by the wireless radio circuit over the time period;
dividing the actual wireless data value by the maximum wireless data value to determine a scaled heat rise generated by the wireless radio circuit over the time period; and
multiplying the scaled heat rise by a wireless gain to determine the wireless heat rise.

4. The method of claim 3 , wherein identifying the maximum wireless data value comprises performing at least one of:
identifying a preset firmware value;
receiving a value for the maximum wireless data value from a user setting;
receiving the value for the maximum wireless data value from a wireless HVAC network; or
calculating the value for the maximum wireless data value from at least one of a wireless protocol type, a modulation scheme, and a transmission frequency band.

5. The method of claim 1 , wherein calculating, by the processing circuit, the temperature offset comprises calculating the temperature offset with a temperature compensation filter, wherein the temperature compensation filter is a first order low pass transfer function;
wherein the method further comprises generating, by the processing circuit, an input for the temperature compensation filter by summing at least the wireless offset and the wireless heat rise resulting from the wireless activity.

6. The method of claim 5 , wherein the temperature compensation filter is a discrete-time digital filter that outputs the temperature offset as a function of a previous temperature offset and the wireless heat rise resulting from the wireless activity, wherein the wireless heat rise occurs after the previous temperature offset is calculated.

7. The method of claim 6 , further comprising:
storing, by the processing circuit, the temperature offset upon powering off the controller; and
using, by the processing circuit, the temperature offset as the previous temperature offset in the processing circuit when the controller is powered on.

8. The method of claim 7 , further comprising, upon powering on the controller:
determining, by the processing circuit, whether the controller has been powered off for a first time period exceeding a threshold;
using, by the processing circuit, the temperature offset as the previous temperature offset in the temperature compensation filter if the controller has been powered off for a second time period that does not exceed the threshold; and
resetting, by the processing circuit, the previous temperature offset to zero if the controller has been powered off for the first time period exceeding the threshold.

9. A controller located within a building zone, the controller comprising:
a housing;
a wireless radio contained within the housing, the wireless radio configured to transmit data via a wireless network; and
a processing circuit configured to determine a temperature of the building zone outside the housing based on a mathematical model and based on a temperature measurement, wherein the mathematical model is a function of an actual wireless data value representing an actual amount of wireless data transmitted by the wireless radio over a time period.

10. The controller of claim 9 , wherein the wireless radio causes a second temperature inside the housing to exceed the temperature of the building zone outside the housing by generating heat as a result of wirelessly communicating through a mesh topology to at least one of a Zigbee coordinator and a Zigbee router.

11. The controller of claim 9 , wherein the processing circuit is configured to:
determine a wireless heat rise resulting from wireless activity of the wireless radio;
calculate a temperature offset based on the wireless heat rise; and
determine the temperature of the building zone outside the housing by subtracting the temperature offset from the temperature measurement.

12. The controller of claim 11 , wherein the processing circuit is configured to determine the wireless heat rise resulting from the wireless activity by:
identifying a maximum wireless data value representing a maximum amount of wireless data capable of being transmitted by the wireless radio over the time period;
dividing the actual wireless data value by the maximum wireless data value to determine a scaled heat rise generated by the wireless radio over the time period; and
multiplying the scaled heat rise by a wireless gain to determine the wireless heat rise.

13. The controller of claim 11 , wherein the processing circuit is configured to calculate the temperature offset as a function of both a wireless offset and the wireless heat rise resulting from the wireless activity;
wherein the wireless offset represents a baseline amount of heat generated by the wireless radio independent from the wireless heat rise resulting from the wireless activity.

14. The controller of claim 13 , wherein the processing circuit is configured to calculate the temperature offset using a temperature compensation filter, wherein the temperature compensation filter is a first order low pass transfer function;
wherein the processing circuit is further configured to generate an input for the temperature compensation filter by summing at least the wireless offset and the wireless heat rise resulting from the wireless activity.

15. The controller of claim 14 , wherein the temperature compensation filter is a discrete-time digital filter that outputs the temperature offset as a function of a previous temperature offset and the wireless heat rise resulting from the wireless activity, wherein the wireless heat rise occurs after the previous temperature offset is calculated.

16. The controller of claim 15 , wherein the processing circuit is further configured to:
store the tempe

Assignees

• Johnson Controls Tech Co

Inventors

• Erickson Christine R
• Ajax Michael J
• Mccann Christopher J
• Hjortland Daniel R
• Seifi Justin J

Classifications

• F24F3/044

  Systems in which all treatment is given in the central station, i.e. all-air systems · CPC title

• F24F2110/10

  Temperature · CPC title

• G05B19/0428

  Safety, monitoring (G05B19/0423 takes precedence) · CPC title

• F24F11/30 Primary

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• F24F11/62

  characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values · CPC title