HVAC CONTROL SYSTEM HAVING INTEGRATED CPH CYCLING CONTROL AND DEADBAND STAGING

• US 20120078423A1
• Filed: 09/24/2010
• Published: 03/29/2012
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: Trane International Inc. (Trane Technologies plc)
• Inventors: Zhou, John Q., Feinberg, Bert L., Henk, Randy L.
• Granted Patent: US 8,321,058 B2
• Time in Patent Office: Days
• US Class Current: 700/278
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/80 for controlling the temperature of the supplied air
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: G05D 23/1902 characterised by the use of a variable reference value

Abstract

A method of controlling an HVAC system including programming a thermostat of the HVAC system to define a temperature set point, a temperature differential around the temperature set point, and a number of cycles per hour for a temperature control source of the HVAC system. The method also includes sensing a temperature, executing a cycling control algorithm that includes the temperature, the temperature set point, and the number of cycles per hour as inputs to determine a duty cycle, and running the temperature control source according to the duty cycle when the temperature is within the temperature differential. The method further includes executing a deadband algorithm to turn on the temperature control source when the temperature is outside of the temperature differential at one extreme and to turn off the temperature control source when the temperature is outside the temperature differential at the opposite extreme.

Claims

1. A method of controlling a heating, ventilation, and air-conditioning (“

HVAC”

) system, the method comprising;

programming a thermostat of the HVAC system to define a temperature set point, a temperature differential around the temperature set point, and a number of cycles per hour for a temperature control source of the HVAC system;

sensing a temperature;

executing a cycling control algorithm that includes the temperature, the temperature set point, and the number of cycles per hour as inputs to determine a duty cycle;

running the temperature control source according to the duty cycle when the temperature is within the temperature differential; and

executing a deadband algorithm to turn on the temperature control source when the temperature is outside of the temperature differential at one extreme and to turn off the temperature control source when the temperature is outside the temperature differential at the opposite extreme.

2. The method of claim 1, further comprising the step of:

executing a proportional-integral loop as a component of the cycling control algorithm, the proportional-integral loop including the temperature and the temperature set point as inputs to determine a required source capacity from the temperature control source.

3. The method of claim 2, further comprising the step of:

executing, continuously, the proportional-integral loop.

4. The method of claim 2, wherein the temperature control source includes a plurality of stages and further comprising the steps of:

executing the cycling control algorithm to determine a required stage capacity for each of the plurality of stages based on the required source capacity;

executing the cycling control algorithm to determine a stage duty cycle for each of the plurality of stages based on the corresponding required stage capacity.

5. The method of claim 1, further comprising the steps of:

programming the thermostat to define a second temperature set point, a second temperature differential around the second temperature set point, and a second number of cycles per hour for a second temperature control source of the HVAC system;

executing a second cycling control algorithm that includes the temperature, the second temperature set point, and the second number of cycles per hour as inputs to determine a second duty cycle;

running the second temperature control source according to the second duty cycle when the temperature is within the second temperature differential; and

executing the deadband algorithm to turn on the second temperature control source when the temperature is outside of the second temperature differential at one extreme and to turn off the second temperature control source when the temperature is outside the second temperature differential at the opposite extreme.

6. The method of claim 5, further comprising the step of:

executing a proportional-integral loop as a component of the cycling control algorithm, the proportional-integral loop including the temperature and the temperature set point as inputs to determine a required source capacity from the temperature control source.

7. The method of claim 6, further comprising the step of:

executing a second proportional-integral loop as a component of the second cycling control algorithm, the second proportional-integral loop including the temperature and the second temperature set point as inputs to determine a second required source capacity from the second temperature control source.

8. The method of claim 7, further comprising the steps of:

executing, continuously, the proportional-integral loop; and

executing, continuously, the second proportional-integral loop.

9. The method of claim 6, wherein the temperature control source includes a plurality of stages and further comprising the steps of:

executing the cycling control algorithm to determine a required stage capacity for each of the plurality of stages based on the required source capacity;

executing the cycling control algorithm to determine a stage duty cycle for each of the plurality of stages based on the corresponding required stage capacity.

10. The method of claim 9, wherein the second temperature control source includes a plurality of second stages and further comprising the steps of:

executing the second cycling control algorithm to determine a second required stage capacity for each of the plurality of second stages based on the second required source capacity;

executing the second cycling control algorithm to determine a second stage duty cycle for each of the plurality of second stages based on the corresponding second required stage capacity.

11. The method of claim 10, further comprising the steps of:

programming the thermostat to define a second temperature set point by setting a deadband that separates the temperature set point from the second temperature set point.

12. The method of claim 10, further comprising the steps of:

executing, continuously, the proportional-integral loop; and

executing, continuously, the second proportional-integral loop.

13. The method of claim 12, wherein the temperature control source is a heating source and wherein the second temperature control source is a cooling source.

14. A thermostat for controlling a temperature control source, the thermostat comprising:

a temperature sensor operable to sense a temperature within a room and to generate a signal representative of the temperature; and

a controller in electronic communication with the temperature sensor and configured to receive the signal;

wherein the controller is configured to define a temperature set point, a temperature differential around the temperature set point, and a number of cycles per hour for the temperature control source,

wherein the controller is configured to determine a duty cycle by executing a cycling control algorithm that includes the temperature, the temperature set point, and the number of cycles per hour as inputs,

wherein the controller is configured to run the temperature control source according to the duty cycle when the temperature is within the temperature differential, and

wherein the controller is configured to execute a deadband algorithm to turn on the temperature control source when the temperature is outside of the temperature differential at one extreme and to turn off the temperature control source when the temperature is outside the temperature differential at the opposite extreme.

15. The thermostat of claim 14, wherein the cycling control algorithm includes a proportional-integral loop having the temperature and the temperature set point as inputs to determine a required source capacity from the temperature control source.

16. The thermostat of claim 14, wherein the controller is configured to continuously execute the proportional-integral loop.

17. A thermostat for controlling a heating source and a cooling source, the thermostat comprising:

a temperature sensor operable to sense a temperature within a room and to generate a signal representative of the temperature; and

a controller in electronic communication with the temperature sensor and configured to receive the signal;

wherein the controller is configured to define a heating temperature set point, a heating temperature differential around the heating temperature set point, a heating number of cycles per hour for the heating source, a cooling temperature set point, a cooling temperature differential around the cooling set point, and a cooling number of cycles per hour for the cooling source,

wherein the controller is configured to determine a heating duty cycle by executing a heating cycling control algorithm that includes the temperature, the heating temperature set point, and the heating number of cycles per hour as inputs,

wherein the controller is configured to run the heating source according to the heating duty cycle when the temperature is within the heating temperature differential,

wherein the controller is configured to determine a cooling duty cycle by executing a cooling cycling control algorithm that includes the temperature, the cooling temperature set point, and the cooling number of cycles per hour as inputs, and wherein the controller is configured to execute a deadband algorithm to turn on the heating source when the temperature is less than the heating temperature differential, to turn off the heating source when the temperature is greater than the heating temperature differential, to turn on the cooling source when the temperature is greater than the cooling temperature differential, and to turn off the cooling source when the temperature is less than the cooling temperature differential.

18. The thermostat of claim 17, wherein the heating cycling control algorithm includes a heating proportional-integral loop having the temperature and the heating temperature set point as inputs to determine a required heating source capacity from the heating source, and

wherein the cooling cycling control algorithm includes a cooling proportional-integral loop having the temperature and the cooling temperature set point as inputs to determine a required cooling source capacity from the cooling source.

19. The thermostat of claim 18, wherein the heating source includes a plurality of heating stages,

wherein the cooling source includes a plurality of cooling stages,

wherein the controller is configured to determine a heating stage capacity for each of the plurality of heating stages based on the required heating source capacity by executing the heating cycling control algorithm,

wherein the controller is configured to determine a heating stage duty cycle for each of the plurality of heating stages based on the corresponding heating stage capacity by executing the heating cycling control algorithm,

wherein the controller is configured to determine a cooling stage capacity for each of the plurality of cooling stages based on the required cooling source capacity by executing the cooling cycling control algorithm, and

wherein the controller is configured to determine a cooling stage duty cycle for each of the plurality of cooling stages based on the corresponding cooling stage capacity by executing the cooling cycling control algorithm.

20. The thermostat of claim 19, wherein the controller is configured to continuously execute the heating proportional-integral loop, and

wherein the controller is configured to continuously execute the cooling proportional-integral loop.