System and method for compressor capacity modulation

• US 20070032909A1
• Filed: 08/03/2005
• Published: 02/08/2007
• Est. Priority Date: 08/03/2005
• Status: Active Grant

• Current Assignee: Kulthorn Kirby Public Company Limited
• Original Assignee: Bristol Compressors International Incorporated (Kulthorn Kirby Public Company Limited)
• Inventors: Monk, David, Edwards, Jerry, Tolbert, John, Hix, Scott
• Granted Patent: US 7,628,028 B2
• Time in Patent Office: Days
• US Class Current: 700/276
• CPC Class Codes: F25B 2500/26 characterised by the startup of the refrigeration cycle
• CPC Class Codes: F25B 2600/0253 with variable speed
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A system and method is provided to control and operate a compressor to have two or more discrete output capacities in response to an outdoor temperature measurement. During operation of the compressor in an air conditioning or cooling mode, the compressor has a first output capacity in response to the outdoor temperature being greater than a first temperature setpoint and the compressor has a second output capacity in response to the outdoor temperature being less than a second temperature setpoint.

Claims

1. A method for modulating capacity in a compressor for an HVAC&

R system, the method comprising the steps of;

providing a compressor and a motor to power the compressor;

measuring an outdoor ambient temperature;

comparing the measured outdoor ambient temperature to a first predetermined temperature setpoint;

operating the motor for the compressor at a first output frequency and corresponding voltage in response to the measured outdoor ambient temperature being greater than the first predetermined temperature setpoint, wherein operation of the motor at the first output frequency and corresponding voltage results in a first output capacity for the compressor;

comparing the measured outdoor ambient temperature to a second predetermined temperature setpoint;

operating the motor for the compressor at a second output frequency and corresponding voltage in response to the measured outdoor ambient temperature being less than or equal to the second predetermined temperature setpoint, wherein operation of the motor at the second output frequency and corresponding voltage results in a second output capacity for the compressor; and

wherein a single speed fan is used with at least one of a condenser arrangement or an evaporator arrangement of an HVAC&

R system.

2. The method of claim 1 further comprising the step of repeating either the step of operating the motor for the compressor at a first output frequency and corresponding voltage or the step of operating the motor for the compressor at a second output frequency and corresponding voltage in response to the measured outdoor ambient temperature being between the first predetermined setpoint and the second predetermined setpoint.

3. The method of claim 1 further comprising the step of executing a start-up process for the compressor.

4. The method of claim 3 wherein the step of executing a start-up process for the compressor includes slowly increasing motor speed and/or torque during initial starting of the motor.

5. The method of claim 3 wherein the step of executing a start-up process for the compressor includes the steps of:

measuring an outdoor ambient temperature;

comparing the measured outdoor ambient temperature to the first predetermined temperature setpoint;

operating the motor for the compressor at the first output frequency and corresponding voltage in response to the measured outdoor ambient temperature being greater than or equal to the first predetermined temperature setpoint; and

operating the motor for the compressor at the second output frequency and corresponding voltage in response to the measured outdoor ambient temperature being less than the first predetermined temperature setpoint.

6. The method of claim 1 further comprising the step of programming, by a user, at least one of the first predetermined temperature setpoint, the first output frequency, the second predetermined temperature setpoint, or the second output frequency.

7. The method of claim 1 further comprising the steps of:

measuring a motor current for the motor; and

detecting for an overload condition or an underload condition in the motor using the measured motor current and the measured outdoor ambient temperature.

8. The method of claim 1 wherein the second output frequency is less than the first output frequency and the second output capacity is less than the first output capacity for an air conditioning mode of operation.

9. The method of claim 8 wherein the second output capacity is between about 15% and about 20% less than the first output capacity.

10. The method of claim 9 wherein the second output capacity is about 18% less than the first output capacity.

11. The method of claim 8 wherein the first predetermined temperature setpoint is between about 88°

F. and about 95°

F., the second predetermined temperature setpoint is between about 82°

F. and about 88°

F. and the first predetermined temperature setpoint and the second predetermined temperature setpoint are separated by a deadband of between about 2°

F. and about 10°

F.

12. The method of claim 8 wherein the first output frequency is between about 35 Hz and about 55 Hz and the second output frequency is between about 28 Hz and about 45 Hz.

13. The method of claim 1 wherein the second output frequency is greater than the first output frequency and the second output capacity is greater than the first output capacity for a heating mode of operation.

14. The method of claim 13 wherein the first predetermined temperature setpoint is equal to or greater than the second predetermined temperature setpoint.

15. The method of claim 1 further comprising the steps of:

detecting for an override signal indicating a need for increased compressor capacity;

operating the motor for the compressor at the first output frequency and corresponding voltage in response to the detection of the override signal during a cooling mode operation; and

operating the motor for the compressor at the second output frequency and corresponding voltage in response to the detection of the override signal during a heating mode operation.

16. An HVAC&

R system comprising;

a compressor, a condenser arrangement and an evaporator arrangement connected in a closed refrigerant loop, the condenser arrangement and the evaporator arrangement each having a fan arrangement operating at a single speed;

a motor connected to the compressor to power the compressor, the motor being configured to operate at a first output speed to generate a first output capacity from the compressor and to operate at a second output speed to generate a second output capacity from the compressor;

a control system connected to the motor to power the motor, the control system being configured to provide the motor with a first output frequency and corresponding voltage to generate the first output speed from the motor and the control system being configured to provide the motor with a second output frequency and corresponding voltage to generate the second output speed from the motor;

a sensor arrangement to measure a parameter corresponding to an outdoor ambient temperature and to provide a signal to the control system with the measured parameter; and

wherein the control system is configured to provide the motor with the first output frequency and corresponding voltage in response to the measured parameter being greater than a first predetermined setpoint and to provide the motor with a second output frequency and corresponding voltage in response to the measured parameter being less than or equal to a second predetermined setpoint.

17. The HVAC&

R system of claim 16 wherein the sensor arrangement is a temperature sensor and the temperature sensor is configured to measure the outdoor ambient temperature.

18. The HVAC&

R system of claim 17 wherein the first predetermined setpoint is between about 88°

F. and about 95°

F. and the second predetermined setpoint is between about 82°

F. and about 88°

F.

19. The HVAC&

R system of claim 18 wherein the first predetermined setpoint and the second predetermined setpoint are separated by a deadband of between about 2°

F. and about 10°

F.

20. The HVAC&

R system of claim 16 wherein the second output frequency is less than the first output frequency and the second output capacity is less than the first output capacity.

21. The HVAC&

R system of claim 20 wherein the first output frequency is between about 35 Hz and about 55 Hz and the second output frequency is between about 28 Hz and about 45 Hz.

22. The HVAC&

R system of claim 16 wherein the control system comprises a microprocessor and a variable speed drive.

23. The HVAC&

R system of claim 16 wherein the second output frequency is greater than the first output frequency and the second output capacity is greater than the first output capacity.

24. The HVAC&

R system of claim 23 wherein the first predetermined setpoint is equal to or greater than the second predetermined setpoint.

25. The HVAC&

R system of claim 16 wherein;

the control system comprises a temperature sensor to measure a temperature of the control system;

the control system being configured to compare the measured temperature of the control system to a predetermined temperature setpoint; and

the control system being configured to adjust an output frequency provided to the motor in response to the measured temperature of the control system being greater than the predetermined temperature setpoint.

26. The HVAC&

R system of claim 16 wherein the compressor is a reciprocating compressor and the motor is a switched reluctance motor.

27. The HVAC&

R system of claim 16 wherein the compressor has a housing, the control system is mounted on an exterior surface of the housing and the control system is configured to use the housing of the compressor as a heat sink to cool components of the control system.

28. The HVAC&

R system of claim 16 wherein;

the compressor comprises a housing;

the control system is mounted inside the housing; and

the control system is configured to use refrigerant gas circulating inside the housing to cool components of the control system.

29. The HVAC&

R system of claim 28 wherein the motor includes a motor cap disposed on an end of the motor, the motor and motor cap are mounted inside the housing of the compressor, and the control system is mounted inside the motor cap adjacent to the motor.

30. The HVAC&

R system of claim 16 wherein the control system is disposed adjacent to a fluid connection between the condenser arrangement and the evaporator arrangement and the control system is configured to use refrigerant from the fluid connection between the condenser arrangement and the evaporator arrangement to cool components of the control system.

31. The HVAC&

R system of claim 16 wherein the control system is disposed adjacent to a fluid connection between the compressor and the evaporator arrangement and the control system is configured to use refrigerant from the fluid connection between the compressor and the evaporator arrangement to cool components of the control system.

32. The HVAC&

R system of claim 16 wherein the control system comprises a heat sink and at least one fin extending from the heat sink and the control system is configured to use air circulating over the heat sink and the at least one fin to cool components of the control system.

33. A method for modulating capacity in a compressor for an HVAC&

R system, the method comprising the steps of;

providing a compressor and a motor to power the compressor;

measuring an outdoor ambient temperature;

comparing the measured outdoor ambient temperature to a first predetermined temperature setpoint;

operating the motor for the compressor at a first output frequency and corresponding voltage in response to the measured outdoor ambient temperature being less than or equal to the first predetermined temperature setpoint, wherein operation of the motor at the first output frequency and corresponding voltage results in a first output capacity for the compressor;

providing a plurality of additional temperature setpoints less than the first temperature setpoint;

comparing the measured outdoor ambient temperature to each additional temperature setpoint of the plurality of additional temperature setpoints; and

operating the motor for the compressor at a corresponding additional discrete output frequency and corresponding voltage of a plurality of additional discrete output frequencies and corresponding voltages in response to the measured outdoor ambient temperature being less than or equal to an additional temperature setpoint of the plurality of additional temperature setpoints, wherein operation of the motor at a corresponding additional discrete output frequency and corresponding voltage results in an additional output capacity for the compressor different from the first output capacity.

34. The method of claim 33 further comprising the step of:

configuring the HVAC&

R system for heating mode operation; and

wherein the operation of the motor at a corresponding additional discrete output frequency and corresponding voltage results in an additional output capacity for the compressor greater than the first output capacity additional capacity.

35. The method of claim 34 wherein the first predetermined setpoint is between about 50°

F. and about 70°

F. and the first output frequency is between about 35 Hz and about 55 Hz.

36. The method of claim 35 wherein the plurality of additional temperature setpoints include setpoints of about 35°

F., about 40°

F., about 45°

F. and about 50°

F. and the plurality of additional discrete output frequencies include frequencies of about 90 Hz, about 80 Hz, about 70 Hz and about 60 Hz.

37. The method of claim 33 further comprising the steps of:

detecting for a heating signal indicating a need for heating; and

operating the motor for the compressor at the first output frequency in response to the detection of the heating signal.

38. The method of claim 33 further comprising the step of:

configuring the HVAC&

R system for cooling mode operation; and

wherein the operation of the motor at a corresponding additional discrete output frequency and corresponding voltage results in an additional output capacity for the compressor less than the first output capacity additional capacity.

39. The method of claim 38 wherein the first predetermined setpoint is between about 88°

F. and about 95°

F. and the first output frequency is between about 48 Hz and about 55 Hz.

40. The method of claim 39 wherein the plurality of additional temperature setpoints include setpoints of about 35°

F., about 50°

F., about 65°

F. and about 80°

F. and the plurality of additional discrete output frequencies include frequencies of about 30 Hz, about 35 Hz, about 40 Hz and about 45 Hz.

41. The method of claim 39 further comprising the step of operating the motor for the compressor at a second output frequency and corresponding voltage in response to the measured outdoor ambient temperature being greater than or equal to the first predetermined temperature setpoint, wherein operation of the motor at the second output frequency and corresponding voltage results in a second output capacity for the compressor greater than the first output capacity.

42. A method for obtaining a desired performance from an HVAC&

R system, the method comprising the steps of;

providing a programmable controller, the programmable controller providing at least one output frequency and at least one output voltage to a motor powering a compressor of the HVAC&

R system;

setting the at least one output frequency and the at least one output voltage provided by the programmable controller to predetermined initial values;

determining particular system configurations and conditions for the HVAC&

R system;

adjusting the predetermined initial values for at least one of the at least one output frequency or the at least one output voltage in response to the determined particular system configurations and conditions;

testing the HVAC&

R system with the adjusted values for the at least one of the at least one output frequency or the at least one output voltage being provided by the controller;

adjusting the tested values for at least one of the at least one output frequency or the at least one output voltage in response to the determined system performance not being the desired system performance for the HVAC&

R system; and

repeating the steps of testing the HVAC&

R system with the adjusted values and adjusting the tested values for at least one of the at least one output frequency or the at least one output voltage until the desired performance for the HVAC&

R system is obtained.

43. The method of claim 42 wherein the particular system configurations and conditions for the HVAC&

R system include at least one of condenser coil size, evaporator coil size, amount of refrigerant charge, type of refrigerant charge, condenser airflow rate or evaporator airflow rate.