System and method for controlling a system that includes fixed speed and variable speed compressors

Patent metadata

Field	Value
Publication number	US-11092151-B2
Application number	US-201715461927-A
Country	US
Kind code	B2
Filing date	Mar 17, 2017
Priority date	Apr 4, 2013
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A system and method for controlling a system that includes fixed speed and variable speed compressors are described. The method generally allows the system, for example, a heating, ventilating, and air condition (HVAC) system that includes fixed speed and variable speed compressors, to maximize unit modulating capability. The method allows the use of a variable speed compressor that is relatively smaller, which can lead to cost savings, easier installation, manufacturing, etc.

First claim

What is claimed is:

1. A method of controlling operation of a variable speed compressor and a fixed speed compressor in a refrigeration or a heating, ventilating, and air conditioning (HVAC) system, the method comprising:
measuring a parameter;
determining a set point of the measured parameter;
determining a first operating mode based on the measured parameter and the set point;
operating the variable speed compressor and the fixed speed compressor based on the determined first operating mode;
determining a second operating mode;
modulating, by a controller, a speed of the variable speed compressor relative to the fixed speed compressor based on the measured parameter and the set point; and
maintaining the parameter within about 1° F. above the set point and about 1° F. below the set point.

2. The method according to claim 1 , wherein the parameter is maintained within about 0.5 to about 1° F. above the set point and within about 0.5 to about 1° F. below the set point.

3. The method according to claim 1 , wherein the fixed speed compressor includes a plurality of fixed speed compressors that include a first fixed speed compressor and a second fixed speed compressor.

4. The method according to claim 3 , further comprising operating the first fixed speed compressor, the second fixed speed compressor, and the variable speed compressor at one of a plurality of operational stages, the plurality of operational stages being different, the plurality of operational stages corresponding to an operational state.

5. The method according to claim 4 , wherein the plurality of operational stages include a first operational stage and a second operational stage, wherein a portion of the first operational stage and a portion of the second operational stage overlap.

6. The method according to claim 5 , wherein the overlap provides a continuous capacity control having no stage gap between the plurality of stages.

7. The method according to claim 5 , wherein the overlap is set based on a dynamic buffer value expressed as a percentage.

8. The method according to claim 7 , wherein the overlap is represented by the first operational stage plus the dynamic buffer value representing a higher capacity than a minimum capacity in the second operational stage.

9. A method of controlling operation of a variable speed compressor, a first fixed speed compressor, and a second fixed speed compressor in a refrigeration or a heating, ventilating, and air conditioning (HVAC) system, the method comprising:
measuring a parameter;
determining a set point of the parameter;
determining a first operating mode based on the measured parameter and the set point;
operating the variable speed compressor, the first fixed speed compressor, and the second fixed speed compressor based on the determined first operating mode;

determining a second operating mode;
modulating, by a controller, a speed of the variable speed compressor relative to the fixed speed compressors based on the measured parameter and the set point;
operating the first fixed speed compressor, the second fixed speed compressor, and the variable speed compressor at one of a plurality of operational stages, the plurality of operational stages being different, and
corresponding the plurality of operational stages to an operational state,
wherein the plurality of operational stages include a first operational stage and a second operational stage,
wherein a portion of the first operational stage and a portion of the second operational stage overlap,
wherein the overlap provides a continuous capacity control having no stage gap between the plurality of stages.

10. The method according to claim 9 , wherein the overlap is set based on a dynamic buffer value expressed as a percentage.

11. The method according to claim 10 , wherein the overlap is represented by the first operational stage plus the dynamic buffer value representing a higher capacity than a minimum capacity in the second operational stage.

12. The method according to claim 9 , wherein the measured parameter includes a discharge air temperature, and the discharge air temperature is maintained within about 1° F. above the set point and about 1° F. below the set point.

13. The method according to claim 12 , wherein the discharge air temperature is maintained within about 0.5 to about 1° F. above the set point and within about 0.5 to about 1° F. below the set point.

14. A system, comprising:
a variable speed compressor;
a fixed speed compressor;
and a controller, wherein the controller:
measures a discharge air temperature;
determines a set point of the discharge air temperature;
determines a first operating mode based on the measured discharge air temperature and the set point;
operates the variable speed compressor and the fixed speed compressor based on the determined first operating mode;
determines a second operating mode;
modulates a speed of the variable speed compressor relative to the fixed speed compressor based on the measured discharge air temperature and the set point; and
maintains the discharge air temperature within about 1° F. above the set point and about 1° F. below the set point.

15. The system according to claim 14 , wherein the discharge air temperature is maintained within about 0.5 to about 1° F. above the set point and within about 0.5 to about 1° F. below the set point.

16. The system according to claim 14 , wherein the fixed speed compressor includes a plurality of fixed speed compressors that include a first fixed speed compressor and a second fixed speed compressor.

17. The system according to claim 16 , wherein the controller operates the first fixed speed compressor, the second fixed speed compressor, and the variable speed compressor at one of a plurality of operational stages, the plurality of operational stages being different, the plurality of operational stages corresponding to an operational state.

18. The system according to claim 17 , wherein the plurality of operational stages include a first operational stage and a second operational stage, wherein a portion of the first operational stage and a portion of the second operational stage overlap.

19. The system according to claim 18 , wherein the overlap provides a continuous capacity control having no stage gap between the plurality of stages, the overlap being set based on a dynamic buffer value expressed as a percentage.

20. The system according to claim 19 , wherein the overlap is represented by the first operational stage plus the dynamic buffer value representing a higher capacity than a minimum capacity in the second operational stage.

Assignees

• Trane Int Inc

Inventors

• Zhou John Qianghua
• Voorhis Roger Joseph
• Joiner Caleb Ryan
• Hayes Benjamin
• Crolius James Philip
• Hansen William

Classifications

• F04D27/0269

  by changing flow path between different stages or between a plurality of compressors; load distribution between compressors · CPC title

• F04C28/08

  characterised by varying the rotational speed · CPC title

• Y02B30/70

  Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating · CPC title

• F25B2600/0253

  with variable speed · CPC title

• F04B49/065 Primary

  and making use of computers · CPC title