Temperature control balancing desired comfort with energy cost savings

• US 6,785,630 B2
• Filed: 02/04/2002
• Issued: 08/31/2004
• Est. Priority Date: 02/04/2002
• Status: Active Grant

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Archacki, Raymond J. Jr., Kolk, Richard A.
• Primary Examiner(s): SHAH, KAMINI S
• Application Number:
  US10/067,103
• Publication Number:
  US 20030149539A1
• Time in Patent Office: 939 Days
• Field of Search: 236/49.3, 236/51, 340/870.02, 702/130, 700/38, 700/44, 703/2, 237/8.R
• US Class Current: 702/130
• CPC Class Codes: G01K 3/00 Thermometers giving results other than momentary value of temperature G01K7/42 takes precedence
• CPC Class Codes: G05D 23/1923 using thermal energy, the cost of which varies in function of time

Abstract

A temperature regulating system utilizes changing energy price information to alter the system operation. A performance index value is determined that indicates a balance between a user'"'"'s preference for maintaining a setpoint temperature and a need for maintaining energy cost savings. The performance index value is related to the current energy price and the system automatically responds to rising energy prices by reducing system operation in a manner that provides cost savings according to a user'"'"'s specified preference for weighting temperature comfort levels compared to energy cost savings. According to the described example, an optimal control solution is used to determine the performance index value.

Claims

1. A method of controlling a temperature regulating system, comprising the steps of:

defining a performance index that indicates a desired balance between maintaining a user selected setpoint temperature and conserving energy costs;

determining a current energy cost;

determining a value of the performance index using an optimal control solution and the current energy cost; and

adjusting a sensitivity of the system to a difference between the setpoint temperature and a current actual temperature according to the performance index value.

2. The method of claim 1, including reducing the sensitivity when the performance index value indicates that conserving energy costs is preferable to maintaining the user-selected setpoint temperature based upon the current energy cost.

3. The method of claim 2, including subsequently increasing the sensitivity when the performance index value changes because the current energy cost is relatively lower.

4. The method of claim 1, including reducing the sensitivity responsive to an increase in the energy cost.

5. The method of claim 4, including adjusting the sensitivity by adjusting a time within which the system reacts to the temperature difference.

6. The method of claim 4, including automatically at least temporarily resetting the setpoint temperature responsive to the performance index value.

7. The method of claim 1, including determining the performance index by estimating a value of $\mathrm{PI}={\int }_{}^{}$

0∝



(QT2+Ru2)

 





u

wherein Q is a user-selected weighting factor indicating the user'"'"'s desire to maintain the setpoint temperature;

T is the temperature difference;

R is a determined weighting factor indicating the need to balance energy cost savings with the user'"'"'s desire to maintain the setpoint temperature; and

u is a value indicating system operation responsive to the temperature difference.

8. The method of claim 7, including estimating the performance index using a degenerate Ricatti equation.

9. The method of claim 1, including using the performance index value to determine a gain value and applying the gain value to the system control signal.

10. The method of claim 9, including determining the gain value by determining a value of k^T=−

PBR<sup>−

1</sup>

wherein k is the gain value;

P is the estimated performance index value;

B is a predetermined system gain value; and

R is a determined weighting factor indicating the need to balance energy cost savings with the user'"'"'s desire to maintain the setpoint temperature.

11. A temperature regulating system, comprising:

a thermostat device having a user input portion that allows a user to input a setpoint temperature and a sensor portion that provides an indication of a current temperature near the thermostat device;

a communication module that is capable of receiving information from an outside source remote from the thermostat device; and

a controller that determines a current energy price from information received by the communication module, determines a performance index value indicative of a balance between a user-specified desire to maintain the setpoint temperature and energy cost savings and automatically adjusts a sensitivity of the system to a difference between the current temperature and the setpoint temperature according to the performance index value.

12. The system of claim 11, wherein the controller automatically slows down a response time of the system to the temperature difference responsive to an increase in energy costs.

13. The system of claim 11, wherein the controller automatically at least temporarily resets the setpoint temperature responsive to an increase in energy costs.

14. The system of claim 11, wherein the controller automatically adjusts a gain of a control value that directs an amount of airflow through the system according to the performance index value.

15. The system of claim 11, wherein the controller determines the gain value by determining a value of k^T=−

PBR<sup>−

1</sup>

wherein k is the gain value;

P is the estimated performance index value;

B is a predetermined system gain value; and

R is a determined weighting factor indicating the need to balance energy cost savings with the user'"'"'s desire to maintain the setpoint temperature.

16. The system of claim 11, wherein the controller determines the performance index by estimating a value of $\mathrm{PI}={\int }_{}^{}$

0∝



(QT2+Ru2)

 





u

wherein Q is a user-selected weighting factor indicating the user'"'"'s desire to maintain the setpoint temperature;

T is the temperature difference;

R is a determined weighting factor indicating the need to balance energy cost savings with the user'"'"'s desire to maintain the setpoint temperature; and

u is a value indicating system operation responsive to the temperature difference.

17. The system of claim 16, wherein the controller estimates the performance index using a degenerate Ricatti equation.

18. The system of claim 16, wherein R is a ratio of the current energy price to a predetermined nominal energy price.