Apparatus for temperature control using a cycle rate control algorithm

• US 7,400,942 B2
• Filed: 01/18/2006
• Issued: 07/15/2008
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: Computime Electronics Company Limited
• Original Assignee: Computime Electronics Company Limited
• Inventors: Cheng, Chung Ming
• Primary Examiner(s): VON BUHR, MARIA N
• Application Number:
  US11/334,259
• Publication Number:
  US 20070168084A1
• Time in Patent Office: 909 Days
• Field of Search: 700 40- 43, 700276-278, 236/1.B, 236/1.C, 236/46.R, 236 91 D- 91 G, 621/25, 621/32, 62159-164, 165/200, 165/201, 165/238, 165/239, 165/243, 165253-258, 165/265, 165267-269, 165287-289
• US Class Current: 700/276
• 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 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/65 for selecting an operating mode
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: G05D 23/1917 using digital means

Abstract

The present invention controls a room temperature by controlling an environmental control unit. A total span about a setpoint temperature is adjusted in accordance with a previous total span and a multiplicative factor. The multiplicative factor is periodically updated from a desired cycle time and a previous cycle time. The room temperature may also be controlled by adjusting a duty cycle for controlling an environmental control unit. The duty cycle is adjusted based on an error associated with a previous control cycle and an attenuation factor. A new control cycle may be started by cutting the previous control cycle or a current control cycle may be extended if a predetermined condition is detected. The control mode is selected based on environmental characteristics and room characteristics. The control mode may include a span control mode and a duty cycle control mode that is selected from the cycle rate.

Claims

1. An apparatus that controls a temperature of a room, the apparatus comprising:

a temperature sensor that measures the temperature; and

a processing unit that controls an environmental control unit and that is configured to perform;

(a) determining a control mode;

(b) if the control mode equals a span control mode, adjusting a current total span of a current control cycle based on a desired cycle time and a previous cycle time; and

(c) if the control mode equals a duty cycle control mode, adjusting a duty cycle of the current control cycle based on an error of a previous control cycle.

2. The apparatus of claim 1, wherein the processing unit is further configured to perform:

(b)(i) obtaining a previous total span of the previous control cycle; and

(b)(ii) multiplying the previous total span by a multiplicative factor.

3. The apparatus of claim 1, wherein the multiplicative factor is determined from a ratio equal to the desired cycle time divided by the previous cycle time.

4. The apparatus of claim 1, wherein the processing unit is further configured to perform:

(c)(i) determining the error from a setpoint temperature and a predicted temperature.

5. The apparatus of claim 4, wherein the predicted temperature is based on an average temperature and a temperature change of the previous control cycle.

6. The apparatus of claim 4, wherein the processing unit is further configured to perform:

(c)(ii) multiplying the error by an attenuation factor.

7. The apparatus of claim 6, wherein the processing unit is further configured to perform:

(c)(iii) adjusting the attenuation factor to match a characteristic of the room.

8. The apparatus of claim 1, wherein the environmental control unit comprises a heating unit.

9. The apparatus of claim 1, wherein the environmental control unit comprises a cooling unit.

10. The apparatus of claim 1, wherein the processing unit is further configured to perform:

(a)(i) if a cycle rate exceeds a predetermined limit, setting the control mode to the duty cycle control mode; and

(a)(ii) if the cycle rate is less than or equal to the predetermined limit, setting the control mode to the span control mode.