ECONOMIZER/DCV CONTROLLER WITH MANUAL SENSOR CALIBRATION

• US 20120078563A1
• Filed: 09/24/2010
• Published: 03/29/2012
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Grabinger, Cory, Thomle, Adrienne, Mikulica, Miroslav
• Granted Patent: US 10,018,370 B2
• Time in Patent Office: Days
• US Class Current: 702/104
• CPC Class Codes: F24F 11/0001 for ventilation F24F11/30 takes precedence
• 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 11/62 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 11/63 Electronic processing
• CPC Class Codes: F24F 2110/00 Control inputs relating to air properties

Abstract

An economizer controller with sensor calibration. A controller sensor may be used to measure a parameter. At the same time at the same location of the measurement with the controller sensor, a measurement of the same parameter may be made with a precision sensor. The difference between the two measurements may be saved to a controller memory as an offset. The offset may be used to compensate future measurements of the same parameter by the controller sensor. Additional offsets at various magnitudes may be obtained between the precision and the controller sensors for compensating subsequent measurements by the controller sensor. Measurements with the compensated sensor may be used for calibrating sensors in other economizer controllers, for example, at remote locations in the field.

Claims

1. A calibrating mechanism for an economizer controller comprising:

a precision sensor of a first kind; and

a first system sensor of the first kind of an economizer controller; and

wherein;

the first system sensor is read to obtain a first value in a first ambient environment at a first time;

the precision sensor is read to obtain a second value in the first ambient environment at the first time;

the first value is compared with the second value to obtain a first offset from a difference between the first and second values;

the first system sensor is read to obtain a third value at a second time; and

the third value of the first system sensor is adjusted by incorporating the first offset to obtain a compensated third value of the first system sensor.

2. The mechanism of claim 1, further comprising:

a second system sensor of the first kind of a second economizer controller; and

wherein;

the second system sensor is read to obtain a fourth value in a second ambient environment at a third time;

the first system sensor is read to obtain a fifth value in the second ambient environment at the third time;

the fifth value of the first system sensor is adjusted by incorporating the first offset to obtain a compensated fifth value of the first system sensor;

the fourth value is compared with the compensated fifth value to obtain a second offset from a difference between the fourth and compensated fifth values;

the second system sensor is read to obtain a sixth value at a fourth time; and

the sixth value of the second system sensor is adjusted by incorporating the second offset to obtain a compensated sixth value of the second system sensor.

3. The mechanism of claim 1, wherein:

the first system sensor is read to obtain a fourth value in the first ambient environment at a third time;

the precision sensor is read to obtain a fifth value in the first ambient environment at the third time; and

the fourth value of the first system sensor is compared with the fifth value of the precision sensor to obtain a second offset from a difference between the fourth and fifth values.

4. The mechanism of claim 3, wherein the first and second offsets are combined to provide a curve of offsets versus values from the first system sensor, which is extrapolated for obtaining offsets for other values obtained by the first system sensor.

5. The mechanism of claim 4, wherein the curve is extrapolated for obtaining offsets for compensating various values from the first system sensor.

6. The mechanism of claim 5, wherein:

the first system sensor is read to obtain a sixth value at a fourth time; and

an offset is determined from the curve for compensating the sixth value.

7. The mechanism of claim 1, wherein a sensor of the first kind is a temperature sensor.

8. The mechanism of claim 1, wherein a sensor of the first kind is a relative humidity sensor.

9. The mechanism of claim 1, wherein a sensor of the first kind is a CO2 sensor.

10. A method for calibrating a system sensor in an economizer controller, comprising:

measuring a first parameter with a system sensor of an economizer controller to get a first reading;

measuring the first parameter with a precision sensor to get a second reading;

computing an offset from a difference between the first and second readings;

entering the offset into a memory of the economizer controller; and

using the offset for calibrating other readings from the system sensor.

11. The method of claim 10, wherein:

the first reading from the system sensor is X;

the second reading from the precision sensor is Y;

|X−

Y| is the offset;

if X is greater than Y, then the offset is subtracted from a subsequent reading from the system sensor for compensation of the subsequent reading; and

if Y is greater than X, then the offset is added to a subsequent reading from the system sensor for compensation of the subsequent reading.

12. The method of claim 10, wherein:

the readings of the precision sensor and the system sensor are stored in the economizer controller; and

determination for the offset from the readings of the precision sensor and the system sensor, and compensation of a subsequent reading of the system sensor are automatically processed.

13. The method of claim 12, wherein determination for the offset from the readings of the precision sensor and the system sensor, and compensation of a subsequent reading of the system sensor are automatically processed by the economizer controller.

14. The method of claim 10, further comprising:

measuring the first parameter with the system sensor of the economizer controller to get a first reading at each of a plurality of ambient temperatures;

measuring the first parameter with the precision sensor to get a second reading at each of the plurality of ambient temperatures;

computing an offset from a difference between the first and second readings of the first parameter for each of the plurality of ambient temperatures;

using an offset, computed at a temperature of the plurality of ambient temperatures, for calibrating another reading from the system sensor of the first parameter obtained at the same temperature that the offset was computed; and

the first parameter is a non-temperature parameter.

15. A method for calibrating a system sensor of an economizer controller, comprising:

taking a plurality of readings with a system sensor of an economizer controller at a first set of different values of a parameter;

taking a plurality of readings with a precision sensor at the first set of different values of the parameter for the first set of different values;

determining a plurality of offsets wherein each offset is a comparison of a reading from the system sensor and a reading from the precision sensor at a same time, of the parameter for the first set of different values; and

compensating a reading from the system sensor of a certain value of the parameter with an offset from the plurality of offsets for a value, of the first set of different values, most closely corresponding to the certain value.

16. The method of claim 15, further comprising:

a graphing the plurality of offsets versus readings of the system sensor; and

wherein;

each offset of the plurality of offsets and each corresponding reading of the system sensor is plotted as a point on a graph resulting in a plurality of points on the graph; and

a curve is constructed that fits on the plurality of points on the graph.

17. The method of claim 15, wherein the plurality of offsets versus readings of the system sensor are entered in a look-up table.

18. The method of claim 15, wherein the compensating a reading from the system sensor of a certain value of the parameter with an offset from the plurality of offsets for a value corresponding to the certain value is automatic by the economizer controller for each reading from the system sensor of the parameter.

19. The method of claim 15, wherein:

the economizer controller comprises a user interface for placing the controller in a calibration mode for compensating a reading with an offset determined by a reading from each system sensor relative to a reading from the precision sensor; and

offsets determined for readings of each system sensor are stored at the controller for availability for compensating a reading from a system sensor at the controller in absence of the precision sensor.

20. The method of claim 15, wherein the economizer controller is a digital controller with demand controlled ventilation.