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US 6,854,285 B2Granted
Controller and a method for controlling an expansion valve of a refrigeration system
AssigneeDanfoss A/S
InventorLars Mou Jessen
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AssigneeDanfoss A/S
InventorLars Mou Jessen
Estimating the term…
A controller for an expansion valve of a refrigeration system for cooling a medium is configured to include, in the generation of a control signal, a measure of the evaporation temperature (T0) of the refrigerant in an evaporator and a measure of a property of the cooled medium, preferably without influence from a measure of the superheat temperature (SH) of the refrigerant. The controller comprises a PI-element for integrating and for producing a control signal for the expansion valve for controlling the flow of refrigerant into the evaporator, the PI-element being arranged in an inner control loop, a reference for which is produced by an outer control loop. The controller allows for fast response to disturbances and/or fast response of the medium temperature when the operating conditions of the refrigeration system are changed and/or fast response during start-up of the refrigeration system and maintains stable operation conditions with low, but positive superheating and a stable evaporation pressure.
A method for controlling an expansion valve of a refrigeration system for cooling a medium, the refrigeration system having a refrigerant circulation and comprising at least one compressor, a condenser, an evaporator for evaporating a refrigerant and being arranged in series with the expansion valve, the expansion valve being electronically controllable by means of a control signal, the method comprising including, in the generation of the control signal, an output of a summing junction for summation or subtraction of a first and a second signal, said first signal being derived from at least a measure of the evaporation temperature (T0) of the refrigerant in the evaporator and a measure of a property of the medium.
A controller for controlling an expansion valve of a refrigeration system for cooling a medium, the refrigeration system having a refrigerant circulation and comprising at least one compressor, a condenser, an evaporator for evaporating a refrigerant and being arranged in series with the expansion valve, the expansion valve being electronically controllable by means of a control signal, the controller being configured to include, in the generation of the control signal, an output of a summing junction for summation or subtraction of a first and a second signal, said first signal being derived from at least a measure of the evaporation temperature (T0) of the refrigerant in the evaporator and a measure of a property of the medium.
Dependencies are inferred from the claim text.