초록 ▼

A system includes a plurality of distributed refrigeration units respectively coupled to discrete refrigeration circuits. Each refrigeration unit may include a variable compressor, a fixed compressor, a condensing unit, and a controller. The controller compares an operating condition of the refriger

A system includes a plurality of distributed refrigeration units respectively coupled to discrete refrigeration circuits. Each refrigeration unit may include a variable compressor, a fixed compressor, a condensing unit, and a controller. The controller compares an operating condition of the refrigeration unit to a refrigeration circuit set point to select a compressor staging capable of achieving the refrigeration circuit set point.

대표청구항 ▼

What is claimed is: 1. A commercial refrigeration system comprising: a first refrigeration unit at a retailer and in communication with a first refrigeration case disposed within a retail space, said first refrigeration unit including a first variable capacity compressor operable between a full cap

What is claimed is: 1. A commercial refrigeration system comprising: a first refrigeration unit at a retailer and in communication with a first refrigeration case disposed within a retail space, said first refrigeration unit including a first variable capacity compressor operable between a full capacity mode and a reduced capacity mode and a first fixed capacity compressor operable between a full capacity mode and a zero capacity mode, said first variable capacity compressor and said first fixed capacity compressor being fluidly coupled to a first suction manifold and fluidly coupled to a first discharge manifold, said first suction manifold and said first discharge manifold coupled to a first refrigeration circuit operating within a first temperature range; a first controller associated with said first refrigeration unit to stage said first variable capacity compressor and said first fixed capacity compressor based on a comparison of a first operating condition of said first refrigeration unit to a first refrigeration circuit set point; a second refrigeration unit at the retailer and in communication with a second refrigeration case disposed within the retail space, said second refrigeration unit including a second variable capacity compressor operable between a full capacity mode and a reduced capacity mode and a second fixed capacity compressor operable between a full capacity mode and a zero capacity mode, said first variable capacity compressor and said first fixed capacity compressor being fluidly coupled to a second suction manifold and fluidly coupled to a second discharge manifold, said second suction manifold and said second discharge manifold coupled to a second refrigeration circuit separate from said first refrigeration circuit and operating within a second temperature range different than said first temperature range; and a second controller associated with said second refrigeration unit to stage said second variable capacity compressor and said second fixed capacity compressor based on a comparison of a second operating condition of said second refrigeration unit to a second refrigeration circuit set point. 2. The system of claim 1, wherein said first operating condition is a first suction pressure and said second operating condition is a second suction pressure. 3. The system of claim 2, wherein said first suction pressure is detected at said first suction manifold and said second suction pressure is detected at said second suction manifold. 4. The system of claim 1, wherein said first controller uses proportional integral control in comparing said first operating condition to said first refrigeration circuit set point and said second controller uses proportional integral control in comparing said second operating condition to said second refrigeration circuit set point. 5. The system of claim 1, wherein said first controller selects compressor staging for said first refrigeration circuit using a compressor control algorithm and said second controller selects compressor staging for said second refrigeration circuit using a compressor control algorithm. 6. The system of claim 1, wherein said first controller selects compressor staging using a first look-up table and said second controller selects compressor staging using a second look-up table. 7. The system of claim 6, wherein said first and second look-up tables each include all possible combinations of compressor staging. 8. The system of claim 1, wherein said first controller modulates a capacity of said first variable capacity compressor to achieve said first refrigeration circuit set point and said second controller modulates said second variable compressor to achieve said second refrigeration circuit set point. 9. The system of claim 8, wherein said first controller selectively toggles said first fixed compressor between a run state and a shutdown state to achieve said first refrigeration circuit set point and said second controller selectively toggles said second fixed compressor between a run state and a shutdown state to achieve said second refrigeration circuit set point. 10. The system of claim 1, wherein said first refrigeration unit includes a first condensing unit having a first condenser coil and a first condenser fan and said second refrigeration unit includes a second condensing unit having a second condenser coil and a second condenser fan. 11. The system of claim 10, wherein said first controller is operable to control said first condenser fan based on said first refrigeration circuit set point and said second controller is operable to control said second condenser fan based on said second refrigeration circuit set point. 12. The system of claim 1, wherein said first controller is in communication with a system controller and said second controller is in communication with a system controller. 13. A method comprising: selecting a first set point for a first refrigeration circuit of a commercial refrigeration system at a retailer, the first refrigeration circuit including a first refrigeration case in a retail space coupled to a first refrigeration unit having a first variable capacity compressor and a first fixed capacity compressor; detecting a first operating condition of said first refrigeration circuit; comparing said first operating condition to said first set point; staging said first variable capacity compressor and said first fixed capacity compressor based on said comparison; selecting a second set point for a second refrigeration circuit of the commercial refrigeration system disposed at the retailer, the second refrigeration circuit including a second refrigeration case in the retail space coupled to a second refrigeration unit having a second variable capacity compressor and a second fixed capacity compressor; detecting a second operating condition of said second refrigeration circuit; comparing said second operating condition to said second set point; and staging said second variable capacity compressor and said second fixed capacity compressor based on said comparison. 14. The method of claim 13, wherein said detecting a first operating condition includes detecting a combined suction pressure of said first variable capacity compressor and said first fixed capacity compressor and said detecting a second operating condition includes detecting a combined suction pressure of said second variable capacity compressor and said second fixed capacity compressor. 15. The method of claim 13, wherein said comparing said first operating condition to said first set point and said comparing said second operating condition to said second set point includes using proportional integral control. 16. The method of claim 13, wherein said staging said first variable capacity compressor and said staging said second variable capacity compressor includes use of a compressor control algorithm. 17. The method of claim 13, wherein said staging said first variable capacity compressor and said staging said second variable capacity compressor includes referencing a capacity look-up table. 18. The method of claim 17, wherein said referencing includes selecting from all possible combinations of compressor staging. 19. The method of claim 13, further comprising modulating said first variable capacity compressor to achieve said first set point and modulating said second variable capacity compressor to achieve said second set point. 20. The method of claim 19, further comprising selectively toggling said first fixed capacity compressor between a run state and a shutdown state to achieve said first set point and selectively toggling said second fixed capacity compressor between a run state and a shutdown state to achieve said second set point. 21. The method of claim 13, further comprising communicating compressor staging information from said first refrigeration circuit to a system controller and communicating compressor staging information from said second refrigeration circuit to a system controller. 22. A commercial refrigeration system comprising: a plurality of discrete refrigeration units at a retailer and respectively coupled to independent refrigeration circuits each including a refrigeration case in a retail space, each of said individual refrigeration circuits operating in a different temperature range from another of said independent refrigeration circuits; each of said discrete refrigeration units including at least one compressor fluidly coupled to a suction manifold and fluidly coupled to a discharge manifold; and each of said plurality of discrete refrigeration units including a controller to stage said at least one compressor based on a comparison of an operating condition of a respective said independent refrigeration circuit to a refrigeration circuit set point. 23. The system of claim 22, wherein said operating condition is a suction pressure. 24. The system of claim 23, wherein said suction pressure is detected at said suction manifolds. 25. The system of claim 23, wherein said controller compares said suction pressure to said refrigeration circuit set point to determine a compressor capacity required to achieve said refrigeration circuit set point. 26. The system of claim 25, wherein said controller uses proportional integral control in comparing said suction pressure and said refrigeration circuit set point. 27. The system of claim 25, wherein said controller selects said compressor staging based on said required compressor capacity using a compressor control algorithm. 28. The system of claim 25, wherein said controller selects said compressor staging based on said required compressor capacity using a look-up table. 29. The system of claim 28, wherein said look-up table includes all possible combinations of compressor staging. 30. The system of claim 22, wherein each of said discrete refrigeration units further includes a condensing unit having a condenser coil and a condenser fan. 31. The system of claim 30, wherein said controller is operable to control said condenser fan based on said refrigeration circuit set point. 32. The system of claim 22, wherein said controller is in communication with a system controller. 33. The system of claim 22, wherein each of said discrete refrigeration units includes at least one fixed capacity compressor. 34. The system of claim 22, wherein each of said discrete refrigeration units includes at least one variable capacity compressor. 35. The system of claim 22, wherein each of said discrete refrigeration units includes at least one fixed capacity compressor and at least one variable capacity compressor.