Ventilation airflow rate control

• US 20080188173A1
• Filed: 02/06/2007
• Published: 08/07/2008
• Est. Priority Date: 02/06/2007
• Status: Active Grant

• Current Assignee: Nortek Global HVAC, LLC (Melrose Industries Plc)
• Original Assignee: Nordyne LLC (Melrose Industries Plc)
• Inventors: Chen, Jie, Chen, Yi, Reifel, Allan J., Herzon, Aaron D.
• Granted Patent: US 8,672,733 B2
• Time in Patent Office: Days
• US Class Current: 454/239
• CPC Class Codes: F04D 27/004 by varying driving speed
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

Airflow rates within a ventilation system are controlled using motor speed or torque and motor electric current or pressure. Fan speed or torque may be varied to compensate for differing restriction in ductwork, and may provide a constant airflow rate over a range of varying airflow restriction. Air handlers or air conditioning units may be mass produced in common configurations, and installed in different buildings or structures with different ductwork configurations. Methods operate a fan motor at a present speed or torque, sample speed or torque, sample current of the fan motor or pressure within the ventilation system, calculate a present airflow rate within the ventilation system, calculate a new input setting using the present airflow rate and a target airflow rate, change the speed or torque to the new input setting, and repeat these steps to converge on the target airflow rate, often avoiding overshoot.

Claims

1. An air-handling unit for ventilating an at-least partially enclosed space, the air-handling unit comprising:

a first fan configured to blow air through the air-handling unit to the space;

an electric first motor connected to and configured to turn the first fan; and

a control system configured to use a first input and a second input to control and vary at least one of a speed and a torque of the first motor, wherein the first input is a representation of at least one of the speed and the torque of the first motor, and the second input is a representation of at least one of an electric current of the first motor and a pressure.

2. The air-handling unit of claim 1 wherein the control system is configured to vary at least one of the speed and the torque of the first motor to obtain a substantially fixed airflow rate through the air-handling unit over a range of varying amount of airflow restriction.

3. The air-handling unit of claim 1 further comprising a first heat-transfer coil configured and positioned so that the air blown by the first fan through the air-handling unit passes through the first heat-transfer coil, a fluid passes through the first heat-transfer coil, and heat is transferred via the first heat-transfer coil between the air and the fluid.

4. The air-handling unit of claim 3 wherein the air-handling unit is an air conditioning unit, the fluid is a refrigerant, and the first heat-transfer coil is an evaporator coil.

5. The air-handling unit of claim 4 further comprising, within an enclosure for the air-handling unit, an expansion valve, a compressor, an electric second motor connected to and configured to turn the compressor, a condenser coil, a second fan configured to blow air through the condenser coil, and an electric third motor connected to and configured to turn the second fan.

6. The air-handling unit of claim 4 wherein the control system is configured to vary at least one of the speed and the torque of the first motor to obtain a substantially fixed airflow rate through the first heat-transfer coil substantially independent of airflow restriction external to the air-handling unit over a range of varying amount of airflow restriction.

7. The air-handling unit of claim 1 wherein the second input is the representation of the electric current of the first motor.

8. The air-handling unit of claim 7, the first motor having a first electrical power lead and a second electrical power lead, the air-handling unit further comprising a current sensor comprising a coil surrounding one of the first electrical power lead and the second electrical power lead.

9. The air-handling unit of claim 7 wherein the first input is the representation of the speed of the first motor.

10. The air-handling unit of claim 7 wherein the first input is the representation of the torque of the first motor.

11. A method of controlling an airflow rate within a ventilation system, the method comprising at least the steps of:

starting a fan motor within the ventilation system;

operating the fan motor at a present input setting, wherein the present input setting comprises at least one of a present motor speed setting and a present motor torque setting;

sampling a first representation of a first present parameter of the ventilation system, wherein the first present parameter comprises at least one of a present speed of the fan motor and a present torque of the fan motor;

before, during, or after the step of sampling the first representation, sampling a second representation of a second present parameter of the ventilation system, wherein the second present parameter comprises at least one of a present current of the fan motor and a present pressure within the ventilation system;

calculating a third representation of a present airflow rate within the ventilation system using the first representation and the second representation;

calculating a new input setting using the third representation of the present airflow rate and a fourth representation of a target airflow rate, wherein the new input setting is predicted to provide a new airflow rate within the ventilation system that is closer to the target airflow rate than the present airflow rate;

changing the present input setting to the new input setting; and

repeating at least a plurality of times the steps of sampling the first representation, sampling the second representation, calculating the third representation of the present airflow rate, calculating the new input setting, and changing the present input setting to the new input setting.

12. The method of claim 11 further comprising, after the step of calculating the third representation, a step of evaluating whether the present airflow rate is within a range of the target airflow rate, and if the present airflow rate is not within the range of the target airflow rate, then the step of calculating the new input setting includes using a first formula to calculate the new input setting, and if the present airflow rate is within the range of the target airflow rate, then the step of calculating the new input setting includes using a second formula to calculate the new input setting, wherein the first formula converges on the target airflow rate more quickly than the second formula.

13. The method of claim 11 wherein, for at least an initial present input setting:

the step of sampling the second representation of the second present parameter includes sampling the second representation at least a plurality of times and evaluating stabilization of the second present parameter; and

the third representation, which is used to calculate the new input setting, to which the present input setting is changed, is calculated using samples of the second representation taken after the second present parameter has substantially stabilized.

14. The method of claim 11 wherein the present input setting is initially selected to provide a predicted airflow rate within the ventilation system that is less than the target airflow rate, and wherein the new input setting is selected to provide a new airflow rate that is less than the target airflow rate, to avoid overshooting the target airflow rate.

15. The method of claim 11 wherein the target airflow rate is fixed at a constant value.

16. A method of providing more-consistent performance of air conditioning units that are mass produced and installed in a variety of structures having a variety of different ductwork configurations with different amounts of airflow restriction, the method comprising in any order at least the steps of:

obtaining or providing at least a plurality air conditioning units, each air conditioning unit having a cooling coil, a fan configured to blow air through the cooling coil and to the structure, and an electric fan motor connected to and configured to turn the fan; and

obtaining or providing a control system configured use the method of claim 11 to control the fan motor to at least partially compensate for the different amounts of the airflow restriction of the different ductwork configurations.

17. The method of claim 16 wherein each of the plurality of air conditioning units further comprises an expansion valve, a compressor, a compressor motor connected to and configured to turn the compressor, a condenser coil, a condenser fan configured to blow air through the condenser, and a condenser fan motor connected to and configured to turn the condenser fan, and wherein the cooling coil is an evaporator coil, and wherein the present input setting is initially selected to provide a predicted airflow rate within the ventilation system that is less than the target airflow rate, and wherein the new input setting is selected to provide a new airflow rate that is less than the target airflow rate, to avoid overshooting the target airflow rate.

18. The method of claim 16 further comprising the step of providing an alarm that the airflow restriction of the ductwork is excessive if the third representation of the present airflow rate fails to reach a predetermined value.

19. The method of claim 16 wherein the first present parameter is the present speed of the fan motor.

20. The method of claim 16 wherein the first present parameter is the present torque of the fan motor.

21. The method of claim 16 wherein the second present parameter is the present current of the fan motor.

22. The method of claim 16 wherein the second present parameter is the present pressure within the ventilation system.

23. The method of claim 11 wherein the first present parameter is the present speed of the fan motor.

24. The method of claim 23 wherein the second present parameter is the present current of the fan motor.

25. The method of claim 11 wherein the first present parameter is the present torque of the fan motor.

26. The method of claim 25 wherein the second present parameter is the present current of the fan motor.

27. A mass-produced air conditioning unit for providing more-consistent airflow in a variety of residential structures having a variety of different ductwork configurations with different amounts of airflow restriction, the air conditioning unit comprising:

an evaporator coil;

a first fan configured to move air through the evaporator coil to the space;

an electric first motor connected to and configured to turn the first fan; and

a control system configured to use a first input and a second input to control and vary at least one of a speed and a torque of the first motor, wherein the control system is configured to continuously sample the first input and the second input and vary at least one of the speed and the torque of the first motor to obtain a substantially fixed airflow rate through the evaporator coil over a range of varying amount of airflow restriction.

28. The air conditioning unit of claim 27 wherein the first input is a representation of at least one of the speed and the torque of the first motor, and the second input is a representation of at least one of an electric current of the first motor and a pressure within the air conditioning unit.

29. The air conditioning unit of claim 28 wherein the first input is a representation of the speed of the first motor, and the second input is a representation of the electric current of the first motor.

30. The air conditioning unit of claim 28 wherein the first input is a representation of the torque of the first motor, and the second input is a representation of the electric current of the first motor.