Variable speed HVAC without controller and responsive to a conventional thermostat

• US 5,410,230 A
• Filed: 03/02/1993
• Issued: 04/25/1995
• Est. Priority Date: 05/27/1992
• Status: Expired due to Fees

• Current Assignee: Regal Beloit Electronic Motors Incorporated
• Original Assignee: General Electric Company
• Inventors: Hooker, John M., Shah, Rajendra K., Bessler, Warren F.
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US08/025,099
• Time in Patent Office: 784 Days
• Field of Search: 318/254, 318/439, 318/138, 318/471, 318/483, 318/432, 318/434, 318/53, 318/66, 318/68, 318/77, 364/493, 364/503, 34/523, 34/524, 34/535, 34/543, 34/562, 34/563, 34/572, 62/176, 62/6, 62/156, 62/157, 62/231, 454/222, 454/229, 454/236, 388/803, 388/809, 388/816, 388/730, 388/934
• US Class Current: 318/471
• 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 11/41 Defrosting; Preventing freezing
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 11/84 using valves
• CPC Class Codes: F24F 11/86 by controlling compressors within refrigeration or heat pump circuits
• CPC Class Codes: F24F 11/871 by controlling outdoor fans
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2140/50 Load
• CPC Class Codes: H02H 7/0856 characterised by the protection measure taken
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: Y10S 388/904 Stored velocity profile
• CPC Class Codes: Y10S 388/934 Thermal condition

Abstract

A system for conditioning air in a space by heating or cooling the air to change its temperature. A thermostat located within the space generates a two state temperature signal having a cyclic parameter which corresponds to the temperature of the air in the space as it rises and falls. A compressor supplies refrigerant to a heat exchanger by means of which changes are made in the temperature of the air. A variable speed motor drives the compressor in response to a motor control signal. A controller responds to the temperature signal and senses the cyclic parameter of the temperature signal. The controller generates the motor control signal as a function of the sensed cyclic parameter whereby the motor control signal is provided to the motor to control the torque or speed of the motor.

Claims

1. A system for conditioning air in a space by heating or cooling the air to change its temperature, said system comprising:

a circuit, responsive to the temperature of the air in the space, for generating a two state temperature signal having cycles including a DEMAND state and a NO DEMAND state, each said state corresponding to a difference between the temperature of the air in the space and a set point temperature;

means for changing the temperature of the air;

at least one motor driving the changing means at a speed or torque defined by a motor speed/torque control signal; and

a control responsive to the temperature signal and including means for sensing a DEMAND cycle time period during which the temperature signal is in the DEMAND state and for sensing a NO DEMAND cycle time period during which the temperature signal is in the NO DEMAND state, said control generating the motor speed/torque control signal as a function of both the DEMAND cycle time period and the NO DEMAND cycle time period whereby said motor speed/torque control signal is provided to the at least one motor to control the torque or speed of the at least one motor dependent upon the period of time between each successive state change.

2. The system of claim 1 wherein said motor has a rotatable assembly in driving relation to the changing means;

said system further comprising means for sensing the position of the rotatable assembly and providing a position signal to the control, said control being responsive to the position signal.

4. The system of claim 1 wherein the control comprises:

a memory for storing parameters representative of the system;

means for selecting parameters corresponding to the system; and

a microprocessor responsive to one or more shored parameters, said microprocessor generating the motor control signal responsive to the selected parameters.

5. The system of claim 4 wherein the memory comprises a programmable, nonvolatile memory for storing various parameters which correspond to various characteristics of various systems such as time constants which are a function of the thermal mass of the structure being heated and/or cooled.

6. The system of claim 4 wherein the memory comprises a memory for storing calibrating parameters representative of operation of said motor driving a predetermined load and wherein said microprocessor controls the microprocessor as a function of the calibrating parameters.

7. The system of claim 6 wherein the calibrating parameters include a current offset and a multiplier.

8. The system of claim 4 wherein the memory comprises a memory for storing calibrating parameters representative of operation of said motor driving no load and wherein said microprocessor controls the microprocessor as a function of the calibrating parameters.

9. The system of claim 8 wherein the calibrating parameters include current offset and a multiplier.

10. The system of claim 4 wherein said memory stores parameters representative of an operation of said motor in combination with the system.

11. The system of claim 10 wherein the stored parameters represent the difference between the actual torque generated by the motor and the nominal values thereby representing the combined inaccuracies of the motor in combination with the system.

12. The system of claim 10 wherein the parameters correspond to a constant CFM calibration.

13. The system of claim 4 wherein the memory comprises an EEPROM having one or more of the following parameters stored therein:

speed or air flow rate for various operating modes such as a heating mode and a cooling mode;

speed or air flow rates for different system capacities such as tons of cooling and kilowatts of heating;

parameters defining turn-on and turn-off time delays;

parameters defining motor speed or torque changes over time;

parameters defining the relationship between motor torque and air flow;

parameters defining the relationship between motor speed and air flow; and

parameters defining direction of rotation; and

wherein the motor control signal generated by the microprocessor is a function of at least one of the stored parameters.

14. The system of claim 4 wherein the memory includes a correction factor for tolerance inaccuracies.

15. The system of claim 4 wherein the memory includes a parameter stored therein which is representative of a difference between the actual current being delivered to the motor and the expected nominal current and wherein the motor control signal generated by the microprocessor is a function of the difference.

16. The system of claim 4 wherein the motor has a rotatable assembly including a rotor in driving relation to the changing means and wherein the memory includes a parameter stored therein which is representative of a magnetization level of the rotor and wherein the motor control signal generated by the microprocessor is a function of the magnetization level.

17. The system of claim 4 wherein the memory includes a parameter stored therein which is representative of a difference between the actual torque being delivered to the motor and the expected nominal torque and wherein the motor control signal generated by the microprocessor is a function of the difference.

18. The system of claim 4 wherein the memory includes a parameter stored therein which is representative of a difference between the actual speed of the motor and the expected nominal speed and wherein the motor control signal generated by the microprocessor is a function of the difference.

19. The system of claim 4 wherein the memory includes a parameter stored therein which is representative of a difference between the actual power input into the system and the expected nominal power and wherein the motor control signal generated by the microprocessor is a function of the difference.

20. The system of claim 1 wherein the control includes a microprocessor and wherein during operation the microprocessor generates a speed/torque control signal which increases motor speed/torque of a subsequent one of the cycles when the duty cycle of the temperature signal of a previous one of the cycles is above a preset maximum and the microprocessor generates a speed/torque control signal which decreases motor speed/torque of a subsequent one of the cycles when the duty cycle of the temperature signal of a previous one of the cycles is below a preset minimum.

21. The system of claim 1 wherein the temperature signal generating circuit comprises a thermostat having contacts which close to provide the temperature signal and having an anticipator which anticipates the opening of the contacts and further comprising means for adjusting a power level provided to the anticipator during a subsequent one of the cycles as a function of the period of time during which the contacts of thermostat are closed during a previous one of the cycles.

22. The system of claim 1 wherein the temperature signal generating circuit comprises a thermostat having an anticipator and further comprising means for adjusting a power level provided to the anticipator during a subsequent one of the cycles as a function of the duty cycle of the temperature signal during a previous one of the cycles.

23. The system of claim 22 wherein the adjusting means decreases the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the temperature signal during the previous cycle.

24. The system of claim 22 wherein the adjusting means decreases according to a linear algorithm the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the temperature signal during the previous cycle.

25. The system of claim 24 wherein the linear algorithm comprises:

space="preserve" listing-type="equation">QU1=UBAS1-USLP1*RTEFF

wherein QU1 defines the anticipator value for the current cycle selected as a function of the duty cycle;

UBAS1 defines the baseline steady state anticipator temperature rise;

USPL1 defines the slope of the linear relation between the anticipator value and the duty cycle; and

RTEFF is the duty cycle modified to account for a change in the motor rpm from start of last cycle to start of current cycle.

26. The system of claim 24 wherein the linear algorithm comprises:

space="preserve" listing-type="equation">QU1=UBAS1-USLP1*RTIME

wherein QU1 defines the anticipator value for the current cycle selected as a function of the duty cycle;

UBAS1 defines the baseline steady state anticipator temperature rise;

USPL1 defines the slope of the linear relation between the anticipator value and the duty cycle; and

RTIME is the duty cycle.

3. A system for conditioning air in a space by heating or cooling the air to change its temperature, said system comprising:

a circuit, responsive to the temperature of the air in the space, for generating a two state temperature signal having a DEMAND state and a NO DEMAND state, each said state corresponding to a difference between the temperature of the air in the space and a set point temperature;

means for changing the temperature of the air;

a first motor driving the changing means in response to a motor control signal; and

a first control responsive to the temperature signal and including means for sensing a DEMAND cycle time period during which the temperature signal is in the DEMAND state and for sensing a NO DEMAND cycle time period during which the temperature signal is in the NO DEMAND state, said control generating the motor control signal as a function of both the DEMAND cycle time period and the NO DEMAND cycle time period;

means for moving the air;

a second motor driving the moving means in response to a second motor control signal; and

a second control responsive to the temperature signal and including means for sensing the period of time between state changes of the temperature signal, said second control being independent of said first control and generating the second motor control signal as a function of both the DEMAND cycle time period and the NO DEMAND cycle time period whereby said second motor control signal is provided to the second motor to control the second motor independently of the control of the first motor as controlled by the first control.

27. A system for conditioning air in a space by heating or cooling the air to change its temperature, said system comprising:

a thermostat, responsive to the temperature of the air in the space, for generating a two state temperature signal having a DEMAND state and a NO DEMAND state;

a compressor for changing the temperature of the air;

a motor driving the compressor at a speed or torque defined by a motor speed/torque control signal;

a control responsive to the temperature signal and including means for sensing a DEMAND cycle time period during which the temperature signal is in the DEMAND state, said control generating the motor speed/torque control signal as a function of the DEMAND cycle time period whereby said motor speed/torque control signal is provided to the motor to control the torque or speed of the motor as a function of the DEMAND cycle time period.

28. The system of claim 27 wherein the control comprises:

a memory for storing calibrating parameters representative of operation of said motor driving a predetermined load;

means, responsive to the calibrating parameters and to the temperature signal, for generating the motor control signal to control motor speed or torque.

29. The system of claim 28 wherein the calibrating parameters represent operation of the motor driving no load.

30. The system of claim 28 wherein the calibrating parameters include a current offset and a multiplier.

31. The system of claim 27 wherein the compressor has a predefined operating speed range and wherein said control initially operates the motor to drive the compressor at the midpoint of the range.

32. The system of claim 27 wherein the compressor has a predefined operating speed range and wherein said control operates the motor to drive the compressor at a speed within the range which speed is increasing at a fixed rate during the period that the thermostat indicates the DEMAND state.

33. The system of claim 32 wherein said control operates the motor to drive the compressor at a speed within the range which speed is decreasing at a rate greater than the fixed rate during the period that the thermostat indicates the NO DEMAND state.

34. A method for conditioning air in a space by heating or cooling the air to change its temperature, said method comprising:

generating in response to the temperature of the air in the space a two state temperature signal having cycles including a DEMAND state and a NO DEMAND state, each state corresponding to a difference between the temperature of the air in the space and a set point temperature;

changing the temperature of the air by controlling a motor driving temperature changing means, said motor being controlled in response to a speed/torque control signal;

sensing a DEMAND cycle time period during which the temperature signal is in the DEMAND state;

sensing a NO DEMAND cycle time period during which the temperature signal is in the NO DEMAND state; and

generating the speed/torque control signal as a function of both the DEMAND cycle time period and the NO DEMAND cycle time period whereby the speed/torque of the motor is controlled depending upon the period of time between each successive state change.

36. The method of claim 34 further comprising providing a memory storing time constants which are a function of the thermal mass of the structure being heated and/or cooled and generating said control signals based on said time constants.

37. The method of claim 36 further comprising providing a nonvolatile memory for storing various time constants which correspond to various parameters of various systems and selecting a time constant corresponding to the system.

38. The method of claim 34 further comprising increasing motor speed/torque of a subsequent one of the cycles when the duty cycle of the temperature signal of a previous one of the cycles is above a preset maximum and decreasing motor speed/torque of a subsequent one of the cycles when the duty cycle of the temperature signal of a previous one of the cycles is below a preset minimum.

39. The method of claim 34 further comprising providing a thermostat having contacts which close to provide the temperature signal and having an anticipator which anticipates the opening of the contacts and adjusting a power level provided to the anticipator during a subsequent one of the cycles as a function of the period of time during which the contacts of the thermostat are closed during a previous one of the cycles.

40. The method of claim 34 further comprising providing a thermostat having an anticipator and adjusting a power level provided to the anticipator during a subsequent one of the cycles as a function of the duty cycle of the temperature signal during a previous one of the cycles.

41. The method of claim 40 further comprising decreasing the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the temperature signal during the previous cycle.

42. The method of claim 40 further comprising decreasing according to a linear algorithm the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the temperature signal during the previous cycle.

43. The method of claim 34 further comprising:

storing calibrating parameters representative of operation of said motor driving a predetermined load; and

generating the control signal to control motor speed or torque in response to the calibrating parameters and in response to the temperature signal.

35. A method for conditioning air in a space by heating or cooling the air to change its temperature, said method comprising:

generating in response to the temperature of the air in the space a two state temperature signal having cycles including a DEMAND state and a NO DEMAND state, each said state corresponding to a difference between the temperature of the air in the space and a set point temperature;

changing the temperature of the air in response to a first control signal;

sensing a DEMAND cycle time period during which the temperature signal is in the DEMAND state;

sensing a NO DEMAND cycle time period during which the temperature signal is in the NO DEMAND state; and

generating the first control signal as a function of both the DEMAND cycle time period and the NO DEMAND cycle time period;

moving the air in response to a second control signal; and

generating the second control signal independent of the first control signal generating step and as a function of both the DEMAND cycle time period and the NO DEMAND cycle time period.

44. A method for conditioning air in a space by heating or cooling the air to change its temperature, said method comprising:

generating a two state temperature signal in response to the temperature of the air in the space, the temperature signal having a DEMAND state and having a NO DEMAND state;

changing the temperature of the air by controlling a motor driving temperature changing means, said motor being controlled in response to a speed/torque control signal;

sensing a DEMAND cycle time period during which the temperature signal is in the DEMAND state; and

generating the speed/torque control signal as a function of the DEMAND cycle time period whereby the speed/torque control signal controls the speed/torque of the motor as a function of the DEMAND cycle time period.

45. The method of claim 44 further comprising:

providing a thermostat to generate a two state temperature signal having a first state when the air in the space is above the set point temperature and having a second state when the air in the space is below the set point temperature;

providing a compressor for cooling the air; and

driving the compressor with the motor.

46. The method of claim 45 further comprising providing a predefined operating speed range to the compressor and initially operating the motor to drive the compressor at the midpoint of the range.

47. The method of claim 45 further comprising providing a predefined operating speed range for the compressor and operating the motor to drive the compressor at a speed with the range which speed is increasing at a fixed rate during the period that the thermostat indicates the DEMAND state.

48. The method of claim 47 further comprising operating the motor to drive the compressor at a speed within the range which speed is decreasing at a rate greater than the fixed rate during the period that the thermostat indicates the NO DEMAND state.

49. The method of claim 44 further comprising:

storing calibrating parameters representative of operation of said motor driving a predetermined load; and

generating the control signal to control motor speed or torque in response to the calibrating parameters and in response to the sensed period between state changes.

50. In a system providing cycles of an on/off signal, an apparatus comprising:

a motor operating at a speed or torque defined by a motor speed/torque control signal; and

a control responsive to the on/off signal and including means for sensing a DEMAND period of time between state changes of the on/off signal and for sensing a NO DEMAND period of time between changes of the on/off signal, said control generating the motor speed/torque control signal as a function of both the DEMAND and NO DEMAND periods between state changes whereby said motor speed/torque control signal is provided to the motor to control the torque or speed of the motor dependent upon the DEMAND and NO DEMAND periods between each successive state change.

51. The apparatus of claim 50 wherein the control includes a microprocessor and wherein during operation the microprocessor increases motor speed/torque of a subsequent one of the cycles when the duty cycle of the on/off signal of a previous one of the cycles is above a preset maximum and the microprocessor decreases motor speed/torque of a subsequent one of the cycles when the duty cycle of the on/off signal of a previous one of the cycles is below a preset minimum.

52. The apparatus of claim 50 wherein the system includes a mechanism having contacts which close to provide the cycles of the on/off signal and includes an anticipator which anticipates the opening of the contacts of subsequent cycles of the on/off signals said apparatus further comprising means for adjusting a power level provided to the anticipator during a subsequent one of the cycles as a function of the duty cycle of the on/off signal during a previous one of the cycles.

53. The apparatus of claim 52 wherein the adjusting means decreases the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the on/off signal during the previous cycle.

54. The apparatus of claim 52 wherein the adjusting means decreases according to a linear algorithm the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the on/off signal during the previous cycle.

55. The apparatus of claim 50 wherein the control comprises:

a memory for storing calibrating parameters representative of operation of said motor driving a predetermined load;

means, responsive to the calibrating parameters and to the on/off signal, for generating said motor control signal to control motor speed or torque.

56. The apparatus of claim 55 wherein the calibrating parameters represent operation of the motor driving no load.

57. The apparatus of claim 55 wherein the calibrating parameters include a current offset and a multiplier.

58. In a method using cycles of an on/off signal and using at least one motor in response to a motor speed/torque control signal;

said method comprising;

sensing a DEMAND period of time between state changes of the on/off signal;

sensing a NO DEMAND period of time between state changes of the on/off signal;

generating the motor speed/torque control signal as a function of both the DEMAND and NO DEMAND periods between state changes whereby the speed/torque of the motor depends upon the DEMAND and NO DEMAND periods between each successive state change.

59. The method of claim 58 further comprising increasing speed/torque of the motor during a subsequent one of the cycles when the duty cycle of the on/off signal of a previous one of the cycles is above a preset maximum and decreasing speed/torque of the motor during a subsequent one of the cycles when the duty cycle of the on/off signal of a previous one of the signals is below a preset minimum.

60. The method of claim 58 wherein the method uses a mechanism having contacts which close to provide the cycles of the on/off signal and wherein the method uses an anticipator which anticipates the opening of the contacts of subsequent cycles of the on/off signal, said method further comprising adjusting a power level provided to the anticipator during a subsequent one of the cycles as a function of the duty cycle of the on/off signal during a previous one of the cycles.

61. The method of claim 60 further comprising decreasing the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the on/off signal during a previous cycle.

62. The method of claim 60 further comprising decreasing according to a linear algorithm the power level provided to the anticipator during the subsequent cycle in response to an increase in the duty cycle of the on/off signal during a previous cycle.

63. The method of claim 58 further comprising:

storing calibrating parameters representative of operation of said motor driving a predetermined load; and

generating the motor control signal to control motor speed or torque in response to the calibrating parameters and in response to the on/off signal.