VARIABLE SPEED COMPRESSOR PROTECTION SYSTEM AND METHOD

• US 20090090118A1
• Filed: 10/07/2008
• Published: 04/09/2009
• Est. Priority Date: 10/08/2007
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: Pham, Hung M., Seibel, Stephen M.
• Granted Patent: US 8,459,053 B2
• Time in Patent Office: Days
• US Class Current: 62/228.5
• CPC Class Codes: F04B 2203/0204 Frequency of the electric current
• CPC Class Codes: F04B 2203/0209 Rotational speed
• CPC Class Codes: F04B 39/06 Cooling; Heating; Prevention of freezing
• CPC Class Codes: F04B 39/12 Casings; Cylinders; Cylinder heads; Fluid connections
• CPC Class Codes: F04B 39/123 Fluid connections
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: F04C 18/0215 where only one member is moving
• CPC Class Codes: F04C 2210/227 Steam
• CPC Class Codes: F04C 2210/26 Refrigerants with particular properties, e.g. HFC-134a
• CPC Class Codes: F04C 2240/403 with inverter for speed control
• CPC Class Codes: F04C 2240/803 Electric connectors or cables; Fittings therefor
• CPC Class Codes: F04C 2240/81 Sensor, e.g. electronic sensor for control or monitoring
• CPC Class Codes: F04C 2270/19 Temperature
• CPC Class Codes: F04C 2270/80 Diagnostics
• CPC Class Codes: F04C 23/008 Hermetic pumps
• CPC Class Codes: F04C 28/08 characterised by varying the rotational speed
• CPC Class Codes: F04C 28/24 characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valvesF04C28/10 takes precedence
• CPC Class Codes: F04C 28/28 Safety arrangements; Monitoring
• CPC Class Codes: F04C 29/0085 Prime movers
• CPC Class Codes: F25B 2500/08 Exceeding a certain temperature value in a refrigeration component or cycle
• CPC Class Codes: F25B 2500/19 : Calculation of parameters
• CPC Class Codes: F25B 2500/28 : Means for preventing liquid refrigerant entering into the compressor
• CPC Class Codes: F25B 2600/021 : Inverters therefor
• CPC Class Codes: F25B 2600/025 : by controlling speed
• CPC Class Codes: F25B 2600/2513 : Expansion valves
• CPC Class Codes: F25B 2700/151 : of the compressor motor
• CPC Class Codes: F25B 2700/1931 : Discharge pressures
• CPC Class Codes: F25B 2700/21 : Temperatures
• CPC Class Codes: F25B 2700/21151 : at the suction side of the compressor
• CPC Class Codes: F25B 2700/21152 : at the discharge side of the compressor
• CPC Class Codes: F25B 2700/21163 : of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 2700/21174 : of the refrigerant at the inlet of the evaporator
• CPC Class Codes: F25B 31/006 : Cooling of compressor or motor
• CPC Class Codes: F25B 49/005 : of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 49/022 : Compressor control arrangements
• CPC Class Codes: Y02B 30/70 : Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y10T 137/0318 : Processes
• CPC Class Codes: Y10T 137/85986 : Pumped fluid control

Abstract

A system and method for a compressor may include an inverter drive connected to the compressor that receives electric power and modulates a speed of the compressor by modulating a frequency of the electric power. A control module connected to the inverter drive monitors compressor power data and compressor speed data from the inverter drive, and calculates a saturated condenser temperature of a refrigeration system associated with the compressor based on the compressor power data and the compressor speed data.

Claims

1. A system comprising:

a compressor;

an inverter drive connected to said compressor that receives electric power and modulates a speed of said compressor by modulating a frequency of said electric power;

a control module connected to said inverter drive that monitors compressor power data and compressor speed data from said inverter drive, and that calculates a saturated condenser temperature of a refrigeration system associated with said compressor based on said compressor power data and said compressor speed data.

2. The system of claim 1 further comprising a discharge temperature sensor that outputs a discharge temperature signal corresponding to a discharge temperature of refrigerant exiting said compressor, wherein said control module receives said discharge temperature signal and calculates a discharge superheat temperature associated with said compressor based on said discharge temperature signal and said saturated condenser temperature.

3. The system of claim 2 wherein said control module monitors at least one of an overheat condition and a flood back condition of said compressor based on said calculated discharge superheat temperature.

4. The system of claim 1 wherein said control module accesses compressor map data for said compressor, said compressor map data correlating power and speed data for said compressor with expected saturated condenser temperatures associated with said compressor, wherein said control module determines said saturated condenser temperature based on said compressor map data.

5. The system of claim 2 wherein said control module adjusts at least one of said speed of said compressor and an expansion valve associated with said compressor based on said calculated discharge superheat temperature.

6. The system of claim 5 wherein said control module adjusts said speed of said compressor and said expansion valve to maintain operation of said compressor within a predetermined operating envelope, said predetermined operating envelope including at least one of a maximum flood back limit, a maximum discharge superheat limit, a maximum discharge temperature limit, a minimum discharge superheat limit, a minimum discharge temperature limit, a maximum scroll temperature limit, and a maximum motor temperature limit.

7. The system of claim 2 wherein said control module calculates said saturated condenser temperature and a saturated evaporator temperature by performing multiple iterations of a first function and a second function, said first function associating said saturated condenser temperature with a compressor power, a compressor speed, and said saturated evaporator temperature, and said second function associating said saturated evaporator temperature with said discharge temperature, said compressor speed, and said saturated condenser temperature.

8. The system recited by claim 7 wherein said control module calculates at least one of a compressor capacity and a compressor efficiency of said compressor based on said saturated evaporator temperature, said saturated condenser temperature, and said compressor speed data.

9. A method comprising:

delivering electric power to a compressor with an inverter drive configured to modulate a speed of said compressor by modulating a frequency of said electric power delivered to said compressor;

monitoring compressor power data and compressor speed data from said inverter drive;

calculating a saturated condenser temperature of a refrigeration system associated with said compressor based on said compressor power data and said compressor speed data.

10. The method of claim 9 further comprising receiving a discharge temperature signal from a discharge temperature sensor, said discharge temperature signal corresponding to a discharge temperature of refrigerant exiting said compressor and calculating a discharge superheat temperature associated with said compressor based on said discharge temperature signal and said saturated condenser temperature.

11. The method of claim 10 further comprising monitoring at least one of an overheat condition and a flood back condition of said compressor based on said calculated discharge superheat temperature.

12. The method of claim 9 further comprising accessing compressor map data for said compressor, said compressor map data correlating power and speed data for said compressor with expected saturated condenser temperatures associated with said compressor, wherein said saturated condenser temperature is calculated based on said compressor map data.

13. The method of claim 10 further comprising adjusting at least one of said speed of said compressor and an expansion valve associated with said compressor based on said calculated discharge superheat temperature.

14. The method of claim 13 wherein said speed of said compressor and said expansion valve are adjusted to maintain operation of said compressor within a predetermined operating envelope, said predetermined operating envelope including at least one of a maximum flood back limit, a maximum discharge superheat limit, a maximum discharge temperature limit, a minimum discharge superheat limit, a minimum discharge temperature limit, a maximum scroll temperature limit, and a maximum motor temperature limit.

15. The method of claim 10 further comprising calculating said saturated condenser temperature and a saturated evaporator temperature by performing multiple iterations of a first function and a second function, said first function associating said saturated condenser temperature with a compressor power, a compressor speed, and a saturated evaporator temperature, and said second function associating said saturated evaporator temperature with said discharge temperature, said compressor speed, and said saturated condenser temperature.

16. The method of claim 13 further comprising calculating at least one of a compressor capacity and a compressor efficiency of said compressor based on said saturated evaporator temperature, said saturated condenser temperature, and said compressor speed data.

17. A system comprising:

a compressor;

a suction temperature sensor that outputs a suction temperature signal corresponding to a temperature of refrigerant entering said compressor;

an inverter drive connected to said compressor that receives electric power and modulates a speed of said compressor by modulating a frequency of said electric power;

a heat sink temperature sensor that outputs a heat sink temperature signal corresponding to a temperature of a heat sink associated with said inverter;

a control module connected to said inverter drive that receives said suction temperature signal, that monitors compressor power data and compressor speed data from said inverter drive, and that calculates at least one of a saturated evaporator temperature of a refrigeration system associated with said compressor, a mass flow of refrigerant in said refrigeration system, and a suction superheat associated with said compressor, based on said suction temperature signal, said heat sink temperature signal, said compressor power data, and said compressor speed data.

18. The system of claim 17 wherein said suction temperature sensor is located at an inlet of said compressor.

19. The system of claim 17 wherein said suction temperature is located at an inlet of said inverter drive.

20. The system of claim 17 wherein said control module calculates an inverter heat loss based on said compressor speed data and said compressor power data.

21. The system of claim 20 wherein said control module calculates said mass flow of said refrigerant based on said inverter heat loss, said suction temperature signal, and said heat sink temperature signal.

22. The system of claim 21 wherein said control module calculates said saturated evaporator temperature based on said compressor power data, said compressor speed data, and said mass flow.

23. The system of claim 22 wherein said control module calculates a suction superheat temperature based on said suction temperature signal and said saturated evaporator temperature.

24. The system of claim 23 wherein said control module monitors at least one of an overheat condition and a flood back condition of said compressor based on said calculated suction superheat temperature.

25. The system of claim 23 further comprising an ambient temperature sensor that outputs an ambient temperature signal corresponding to an ambient temperature, wherein said control module receives said ambient temperature signal and calculates a discharge superheat based on said ambient temperature signal and said calculated suction superheat temperature.

26. A method comprising

receiving a suction temperature signal from a suction temperature sensor, said suction temperature signal corresponding to a temperature of refrigerant entering a compressor;

delivering electric power to said compressor with an inverter drive configured to modulate a speed of said compressor by modulating a frequency of said electric power;

receiving a heat sink temperature signal from a heat sink temperature sensor, said heat sink temperature signal corresponding to a temperature of a heat sink associated with said inverter;

monitoring compressor power data and compressor speed data from said inverter drive;

calculating at least one of a saturated evaporator temperature of a refrigeration system associated with said compressor, a mass flow of refrigerant in said refrigeration system, and a suction superheat associated with said compressor, based on said suction temperature signal, said heat sink temperature signal, said compressor power data, and said compressor speed data.

27. The method of claim 26 further comprising calculating an inverter heat loss based on said compressor speed data and said compressor power data.

28. The method of claim 27 further comprising calculating said mass flow of said refrigerant based on said inverter heat loss, said suction temperature signal, and said heat sink temperature signal.

29. The method of claim 28 further comprising calculating said saturated evaporator temperature based on said compressor power data, said compressor speed data, and said mass flow.

30. The method of claim 29 further comprising calculating a suction superheat temperature based on said suction temperature signal and said saturated evaporator temperature.

31. The method of claim 30 further comprising monitoring at least one of an overheat condition and a flood back condition of said compressor based on said calculated suction superheat temperature.

32. The method of claim 30 further comprising receiving an ambient temperature signal from an ambient temperature sensor, said ambient temperature signal corresponding to an ambient temperature and calculating a discharge superheat based on said ambient temperature signal and said calculated suction superheat temperature.