Digital scroll condensing unit controller
First Claim
Patent Images
1. A compressor control system comprising:
- a compressor that is selectively operable while energized in at least two states including a first state corresponding to a first capacity and a second state corresponding to a second capacity lower than said first capacity, said compressor operable to compress a gas between a suction pressure and a discharge pressure;
a pressure sensor for sensing said suction pressure; and
a controller including motor start logic and coupled to said pressure sensor for producing a variable duty cycle control signal in which said duty cycle control signal is a function of said suction pressure, said controller being coupled to said compressor for unloading said compressor when initially energized and causing said compressor to selectively alternate between said first and second states in response to said variable duty cycle control signal, thereby adjusting capacity of said compressor based upon said suction pressure.
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Abstract
A cooling system controller controls the capacity of a variable capacity compressor based upon the temperature of a housing being cooled, the suction pressure of the compressor or both of these criteria. The cooling system controller is capable of controlling either single-evaporator or multiple-evaporator refrigeration systems. The multiple-evaporator systems can have evaporators of similar temperatures or of mixed temperatures. The controller also allows the use of one or more condenser fans that are operated in a lead/lag fashion to control the cooling capability of the system.
167 Citations
49 Claims
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1. A compressor control system comprising:
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a compressor that is selectively operable while energized in at least two states including a first state corresponding to a first capacity and a second state corresponding to a second capacity lower than said first capacity, said compressor operable to compress a gas between a suction pressure and a discharge pressure;
a pressure sensor for sensing said suction pressure; and
a controller including motor start logic and coupled to said pressure sensor for producing a variable duty cycle control signal in which said duty cycle control signal is a function of said suction pressure, said controller being coupled to said compressor for unloading said compressor when initially energized and causing said compressor to selectively alternate between said first and second states in response to said variable duty cycle control signal, thereby adjusting capacity of said compressor based upon said suction pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 46)
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9. A cooling system comprising:
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a housing;
an evaporator disposed in said housing;
a condenser coupled in fluid communication with said evaporator;
a compressor coupled in fluid communication with said evaporator and said condenser, said compressor comprising a gas between a suction pressure and a discharge pressure;
a temperature sensor for sensing temperature;
a pressure sensor for sensing said suction pressure; and
a controller responsive to said suction pressure sensor, said controller being coupled to said condensation fan for controlling said fan based on a temperature sensed by said temperature sensor, a percent duty cycle, and a calculated minimum pressure differential, and said controller being coupled to said compressor for providing a variable duty cycle control signal to said compressor whereby said compressor is modulated between a first capacity state and a second capacity state while operating to thereby adjust the operating capacity of said compressor based on said suction pressure to maintain a specified suction pressure. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A compressor control system for a multiple compressor rack with at least one compressor having a pulse-width modulated capacity, said compressor control system comprising:
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a pressure sensor for sensing a suction pressure of a gas; and
a system controller responsive to said suction pressure sensor including motor start logic and coupled to the at least one compressor for unloading said compressor when initially energized and providing a variable duty cycle control signal to the at least one compressor, whereby said at least one compressor is modulated between a first capacity state and a second capacity state while operating to thereby adjust the operating capacity of the at least one compressor based on said suction pressure to maintain a specified suction pressure. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. A compressor control system comprising:
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a multiple compressor rack with at least one compressor selectively operable while energized in at least two states including a first state corresponding to a first capacity and a second state corresponding to a second capacity lower than said first capacity, said at least one compressor operable to compress a gas between a suction pressure and a discharge pressure;
a pressure sensor for sensing said suction pressure; and
a controller including motor start logic and coupled to said pressure sensor for producing a variable duty cycle control signal in which the duty cycle control signal is a function of said suction pressure, said controller being coupled to said compressor for unloading said compressor when initially energized and causing said compressor to selectively alternate between said first and second states in response to said variable duty cycle control signal, thereby adjusting capacity of said at least one compressor based upon said suction pressure. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. A cooling system comprising:
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a housing;
an evaporator disposed in said housing;
a condenser coupled in fluid communication with said evaporator;
a compressor rack coupled in fluid communication with said evaporator and said condenser, said compressor rack including at least one compressor having a pulse-width modulated variable capacity and being operable between two states;
a pressure sensor for sensing a suction pressure of a gas;
a system controller responsive to said suction pressure sensor including motor start logic and coupled to the at least one compressor for unloading said compressor when initially energized and providing a variable duty cycle control signal to the at least one compressor, whereby said at least one compressor is modulated between a first capacity state and a second capacity state while operating to thereby adjust the operating capacity of the at least one compressor based on said suction pressure to maintain a specified suction pressure. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A compressor control system, comprising:
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a multiple compressor rack with at least one compressor having a pulse-width modulated capacity;
a pressure sensor for sensing suction pressure of gas; and
a system controller responsive to said suction pressure sensor including motor start logic and coupled to said at least one compressor for unloading said compressor when initially energized and providing a variable duty cycle control signal to said at least one compressor, said at least one compressor being modulated between a first capacity state and a second capacity state while operating to adjust the operating capacity of the at least one compressor based on said suction pressure to maintain a specified suction pressure. - View Dependent Claims (42, 43, 44, 45, 47, 48, 49)
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Specification