Adaptive controller for a refrigeration appliance

Abstract

An adaptive system for controlling a refrigeration appliance is provided. More particularly, a system for controlling the cooling of the refrigerator to achieve a desired temperature performance is provided. A variable damper and variable speed evaporator fan are used to dynamically control temperature of the freezer and fresh food compartments. A model of the refrigerator system can be used to determine the settings for the damper and evaporator fan needed to achieve the temperature performance desired.

1 . A method of operating a refrigeration appliance having a fresh food compartment, a freezer compartment, an evaporator, a variable speed evaporator fan for moving air over the evaporator, and a variable damper for controlling the flow of air from the freezer compartment to the fresh food compartment, the method comprising the steps:
 measuring a temperature in the fresh food compartment, T F ;   measuring a temperature in the freezer compartment, T Z ;   comparing T F  and T Z  with the desired setpoint temperatures, T d,F  and T d,Z , and, if T F ≠T d,F,  or T Z ≠T d,Z , then
 determining i) the position of variable damper and ii) the speed of the evaporator fan required to reach T d,F  and T d,Z  according to a predetermined rate of temperature change in either the fresh food compartment or the freezer compartment. 
   
     
     
         2 . A method of operating a refrigeration appliance as in  claim 1 , repeating said steps of measuring T F , measuring T Z , and comparing until T F ≦T d,F , and T Z ≦T d,Z . 
     
     
         3 . A method of operating a refrigeration appliance having a fresh food compartment, a freezer compartment, an evaporator, a variable speed evaporator fan for moving air over the evaporator, and a variable damper for controlling the flow of air from the freezer compartment to the fresh food compartment, the method comprising the steps:
 measuring a temperature in the fresh food compartment, T F ;   measuring a temperature in the freezer compartment, T Z ;   comparing T F  and T Z  with the desired setpoint temperatures, T d,F  and T d,Z , and, if T F≠T   d,F , or T Z ≠T d,Z , then
 determining the rate of change of T F  and T Z  in the fresh food and freezer compartments, respectively; and 
 ascertaining the difference between the actual rate of change of T F  and T Z  in the fresh food and freezer compartments from said determining step with a desired rate of change of change of T F  and T Z  in the fresh food and freezer compartments; 
 causing the difference from said step of ascertaining to become substantially zero by adjusting i) the position of variable damper and ii) the speed of the evaporator fan. 
   
     
     
         4 . A method of operating a refrigeration appliance having a fresh food compartment, a freezer compartment, an evaporator, a variable speed evaporator fan for moving air over the evaporator, and a variable damper for controlling the flow of air from the freezer compartment to the fresh food compartment, the method comprising the steps:
 measuring a temperature in the fresh food compartment, T F ;   measuring a temperature in the freezer compartment, T Z ;   comparing T F  and T Z  with the desired setpoint temperatures, T d,F  and T d,Z , and, if T F ≠T d,F , or T Z ≠T d,Z , then
 using a reference model to determine the desired rate of change of T F  and T Z  in the fresh food and freezer compartments, respectively; 
 determining the actual rate of change of T F  and T Z  in the fresh food and freezer compartments, respectively; and, if the difference between the desired rate of change and the actual rate of change of T F  and T Z  is not less than a predetermined value, ΔT THR , then, 
 using a refrigeration appliance model to calculate the position of the variable damper, the speed of the evaporator fan, or both in order to cause the difference between the desired rate of change and the actual rate of change of T F  and T Z  to be less than a predetermined value, ΔT THR . 
   
     
     
         5 . A refrigerator appliance, comprising:
 a fresh food compartment;   a freezer compartment;   a refrigeration cycle that includes an evaporator;   a variable speed evaporator fan operable in the speed range inclusive of zero to 100 percent;   a variable position damper for controlling the flow of cooled air between the fresh food compartment and the freezer compartment, said damper operable in the range inclusive of fully closed to fully open;   temperature sensors for measuring the temperature of the fresh food compartment T F , the freezer compartment T F , and the evaporator T E ;   a controller configured for:
 receiving temperature measurements from said temperature sensors; 
 comparing T F  and T F  with the desired setpoint temperatures, T d,F  and T d,Z , and, if T F ≠T d,F , or T Z ≠T d,Z , then 
 determining i) the position of the damper and ii) the speed of the evaporator fan required to reach T d,F  and T d,Z  according to a predetermined rate of temperature change in either the fresh food compartment or the freezer compartment. 
   
     
     
         6 . A method of operating a refrigeration appliance having a fresh food compartment, a freezer compartment, an evaporator, a variable speed evaporator fan for moving air over the evaporator, and a variable damper for controlling the flow of air from the freezer compartment to the fresh food compartment, the method comprising the steps:
 measuring a temperature in the fresh food compartment, T F ;   measuring a temperature in the freezer compartment, T Z ;   comparing T F  and T Z  with the desired setpoint temperatures, T d,F  and T d,Z , and, if T F ≠T d,F , or T Z ≠T d,Z , then
 determining the rate of change of T F  and T Z  in the fresh food and freezer compartments, respectively; and 
 ascertaining the difference between the actual rate of change of T F  and T Z  in the fresh food and freezer compartments from said determining step with a desired rate of change of change of T F  and T Z  in the fresh food and freezer compartments; 
 adjusting i) the position of variable damper and ii) the speed of the evaporator fan to reduce the difference between the actual rate of change of T F  and T Z  and the desired rate of change of T F  and T Z ; and, 
   repeating said steps of measuring a temperature in the fresh food compartment, T F , measuring a temperature in the freezer compartment, T Z , and comparing T F  and T Z,  until the different between the actual rate of change of T F  and T Z  and the desired rate of change of T F  and T Z  is less than a predetermined value.