Refrigerator Appliance Adaptive Control Scheme

The present subject matter relates generally to refrigerator appliances, and more particularly to methods of operating refrigerator appliances.

Refrigerator appliances generally include a cabinet that defines chilled chambers for receipt of food items for storage. Insulated, sealing doors are provided for selectively enclosing the chilled food storage chambers.

Refrigerator appliances typically utilize sealed systems for cooling the chilled chambers. A typical sealed system includes at least one evaporator and a fan, and such refrigerator appliances usually include a separate evaporator for each chamber to achieve different temperatures in each of the chilled chambers. Such sealed systems also include a compressor which urges refrigerant through the sealed system, and the compressor may be a variable speed compressor where the operating speed of the compressor influences the rate of cooling provided to each chilled chamber from the respective evaporator.

The compressor of the sealed system is generally more efficient at slower speeds, however, running the compressor too slowly may result in ineffective cooling, e.g., not reaching a desired setpoint temperature in one or both chilled chambers or taking an excessive time to reach the setpoint temperatures. Additionally, installation conditions and usage patterns, e.g., ambient temperatures and door opening frequencies, vary from unit to another, making it difficult to achieve efficient operation across an entire model or series of refrigerator appliances when relying on generalized predetermined operating parameters for all units. For example, such generalized operating parameters may result in inefficient energy consumption in some cases or ineffective cooling in other cases.

Accordingly, refrigerator appliances and methods of operating such appliances which include adaptive control, e.g., for the compressor, would be desired in the art.

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one aspect of the present disclosure, a method of operating a refrigerator appliance is provided. The refrigerator appliance may include a compressor within a sealed system. The method may include operating the compressor within the sealed cooling system of the refrigerator appliance for a first portion of a period of time and deactivating the compressor for a second portion of the period of time. The method further includes determining a duty cycle of the compressor based on a ratio of the first portion of the period of time to the period of time. The method also includes comparing the determined duty cycle of the compressor to a predefined duty cycle. Based on the comparison of the determined duty cycle to the predefined duty cycle, the speed of the compressor is adjusted.

In another aspect of the present disclosure, a refrigerator appliance is provided. The refrigerator appliance may include a compressor within a sealed cooling system and a controller. The controller may be configured for operating the compressor for a first portion of a period of time and deactivating the compressor for a second portion of the period of time. The controller may also be configured for determining a duty cycle of the compressor based on a ratio of the first portion of the period of time to the period of time and comparing the determined duty cycle of the compressor to a predefined duty cycle. Based on the comparison of the determined duty cycle to the predefined duty cycle, the controller adjusts the speed of the compressor.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”).

Terms such as “inner” and “outer” refer to relative directions with respect to the interior and exterior of the refrigerator appliance, and in particular the food storage chamber(s) defined therein. For example, “inner” or “inward” refers to the direction towards the interior of the refrigerator appliance. Terms such as “left,” “right,” “front,” “back,” “top,” or “bottom” are used with reference to the perspective of a user accessing the refrigerator appliance. For example, a user stands in front of the refrigerator to open the doors and reaches into the food storage chamber(s) to access items therein.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a ten percent margin, i.e., including values within ten percent greater or less than the stated value. In this regard, for example, when used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction, e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, e.g., clockwise, or counterclockwise, with the vertical direction V.

Turning now to the figures,provides a perspective view of a refrigerator applianceaccording to an example embodiment of the present disclosure.provides another perspective view of refrigerator appliance when one or more doors,are open. Refrigerator applianceincludes a cabinet or housingthat extends between a top portionand a bottom portionalong a vertical direction V, between a left sideand a right sidealong a lateral direction L, and between a front sideand a rear sidealong a transverse direction T. Each of the vertical direction V, lateral direction L, and transverse direction T are mutually perpendicular to one another and form an orthogonal direction system.

Housingdefines chilled chambers for receipt of food items for storage. In particular, housingdefines fresh food chamberpositioned at or adjacent top portionof housing. Refrigerator appliancealso includes a freezer chamberthat is, for example, arranged at or adjacent bottom portionof housing. As such, refrigerator applianceis generally referred to as a bottom mount refrigerator. It is recognized, however, that the benefits of the present disclosure apply to other types and styles of refrigerator appliances such as, e.g., a top mount refrigerator appliance or a side-by-side style refrigerator appliance. Consequently, the description set forth herein is for illustrative purposes only and is not intended to be limiting in any aspect to any particular chilled chamber configuration.

Refrigerator doorsare rotatably hinged to an edge of housingfor selectively accessing fresh food chamber. In addition, a freezer dooris arranged below refrigerator doorsfor selectively accessing freezer chamber. Freezer dooris coupled to a freezer drawer (not shown) slidably mounted within freezer chamber. Refrigerator doorsand freezer doorare shown in a closed configuration in. As may be seen when refrigerator doorsare in the open configuration, e.g., as illustrated in, various storage components may be provided within one or both of the refrigerated chambersand, such as bins, drawers, and/or shelves, in various combinations.

Refrigerator appliancealso includes a dispensing assemblyfor dispensing liquid water and/or ice. Dispensing assemblyincludes a dispenserpositioned on or mounted to an exterior portion of refrigerator appliance, e.g., on one of doors. Dispenserincludes a discharging outletfor accessing ice and liquid water. An actuating mechanism, shown as a paddle, is mounted below discharging outletfor operating dispenser. In alternative example embodiments, any suitable actuating mechanism may be used to operate dispenser. For example, dispensercan include a sensor (such as an ultrasonic sensor) or a button rather than the paddle. A user interface panelis provided for controlling the mode of operation. For example, user interface panelincludes a plurality of user inputs (not labeled), such as a water dispensing button and an ice-dispensing button, for selecting a desired mode of operation such as crushed or non-crushed ice.

Discharging outletand actuating mechanismare an external part of dispenserand are mounted in a dispenser recess. Dispenser recessis positioned at a predetermined elevation convenient for a user to access ice or water and enabling the user to access ice without the need to bend-over and without the need to open doors. In example embodiments, dispenser recessis positioned at a level that approximates the chest level of a user.

As shown, for instance in, at least one doormay include a door liner defining a sub-compartment, e.g., icebox compartment. Icebox compartmentextends into fresh food chamberwhen refrigerator dooris in the closed position. Although icebox compartmentis shown in door, additional or alterative embodiments may include an icebox compartment defined within door. An ice making assembly or icemaker (not pictured) may be positioned or disposed within icebox compartment. Thus, ice may be supplied to dispenser recess(see) from the icemaker and/or ice dispenser unit in icebox compartmenton a back side of refrigerator door.

An access door, e.g., icebox door, may be hinged to icebox compartmentto selectively cover or permit access to opening of icebox compartment. Icebox doorpermits selective access to icebox compartment. Any manner of suitable latchis provided with icebox compartmentto maintain icebox doorin a closed position. As an example, latchmay be actuated by a consumer in order to open icebox doorfor providing access into icebox compartment. Icebox doorcan also assist with insulating icebox compartment, e.g., by thermally isolating or insulating icebox compartmentfrom fresh food chamber. This thermal insulation helps maintain icebox compartmentat a temperature below the freezing point of water. In addition icebox compartmentmay receive cooling air from a chilled air supply ductand a chilled air return ductdisposed on a side portion of housingof refrigerator appliance. In this manner, the supply ductand return ductmay recirculate chilled air from a suitable sealed cooling system(see) through icebox compartment.

Operation of the refrigerator appliancecan be generally controlled or regulated by a controller. Controllermay control or regulate various portions of refrigerator applianceaccording to one or more discrete criteria. In other words, controllermay be configured to control refrigerator appliance, for example, according to one or more exemplary methods described herein and/or may be configured to perform some or all of such exemplary methods.

In some embodiments, controlleris operatively coupled to user interface paneland/or various other components, as will be described below. User interface panelprovides selections for user manipulation of the operation of refrigerator appliance. As an example, user interface panelmay provide for selections between whole or crushed ice, chilled water, and/or specific modes of operation. In response to one or more input signals (e.g., from user manipulation of user interface paneland/or one or more received sensor signals), controllermay operate various components of the refrigerator applianceaccording to the current mode of operation.

Controllermay include a memory and one or more microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of refrigerator appliance. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In some embodiments, the processor executes programming instructions stored in memory. For certain embodiments, the instructions include a software package configured to operate applianceand, e.g., execute an operation routine including one or more example methods described below. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controllermay be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

Controller, or portions thereof, may be positioned in a variety of locations throughout refrigerator appliance. In example embodiments, controlleris located within the user interface panel. In other embodiments, the controllermay be positioned at any suitable location within refrigerator appliance, such as for example within a fresh food chamber, a freezer door, etc. In additional or alternative embodiments, controlleris formed from multiple controllers or controller components mounted at discrete locations within or on refrigerator appliance. Input/output (“I/O”) signals may be routed between controllerand various operational components of refrigerator appliance. For example, user interface panelmay be operatively coupled to controllervia one or more signal lines or shared communication busses.

In some embodiments, one or more temperature sensorsandare included with refrigerator appliance. As an example, a first temperature sensormay be in operable communication with the fresh food chamberand a second temperature sensormay be in operable communication with the freezer chamberof the refrigerator appliance. Such temperature sensorsandmay, for example, be mounted to a liner within cabinet. During operations, temperature sensorsandmay thus detect the temperature within the respective refrigerated chambersand.

Temperature sensorsandmay be any suitable temperature sensor operatively coupled to controller. For example, one or both of temperature sensorsandmay be a thermistor, a thermocouple, a resistance thermometer, etc. During certain operations, measurements from temperature sensorsandmay be utilized to initiate and/or terminate one or more cycles of sealed cooling system, e.g., when a setpoint temperature is reached in one of the refrigerated chambersor.

In some embodiments, controlleris operatively coupled to the various components of dispensing assemblyand may control operation of the various components. For example, the various valves, switches, etc. may be actuatable based on commands from the controller. As discussed, interface panelmay additionally be operatively coupled to the controller. Thus, the various operations may occur based on user input or automatically through controllerinstruction.

Referring now to, refrigerator appliancemay include a sealed refrigeration or cooling system. In general, sealed cooling systemis charged with a refrigerant that is flowed through various components and facilitates cooling of the fresh food compartmentand the freezer compartment. Sealed cooling systemmay be charged or filled with any suitable refrigerant, such as R441A, R600a, R600, R290, etc.

Sealed cooling systemincludes a compressorfor compressing the refrigerant, thus raising the temperature and pressure of the refrigerant. Compressormay for example be a variable speed compressor, such that the speed of the compressorcan be varied between zero (0%) and one hundred percent (100%) by controller. Sealed cooling systemmay further include a condenser, which may be disposed downstream of compressor, e.g., in the direction of flow of the refrigerant. Thus, condensermay receive refrigerant from the compressor, and may condense the refrigerant by lowering the temperature of the refrigerant flowing therethrough due to, e.g., heat exchange with ambient air. A condenser fanmay be used to force air over condenseras illustrated to facilitate heat exchange between the refrigerant and the surrounding air. Condenser fancan be a variable speed fan-meaning the speed of condenser fanmay be controlled or set anywhere between and including, e.g., zero (0%) and one hundred percent (100%). The speed of condenser fancan be determined, and communicated to fan, by controller.

Sealed cooling systemfurther includes evaporatorsand, e.g., a dedicated evaporator for each of the fresh food chamberthe freezer chamber, disposed downstream of the condenser. Additionally, an expansion device(e.g., a capillary tube, electronic expansion valve, or other similar device) may be utilized to expand the refrigerant, thus further reduce the pressure of the refrigerant, leaving condenserbefore being flowed to evaporatorsand. A valvemay be provided between the expansion deviceand the evaporatorsand, e.g., the valvemay be upstream of the evaporatorsandand may be configured to selectively direct refrigerant flow from the expansion deviceto one or the other of the evaporatorsand. In additional exemplary embodiments, multiple expansion devicesmay be provided, e.g., at least one expansion devicefor each evaporatorand, and the valvemay be immediately downstream of the condenserand upstream of the expansion devicesto selectively direct refrigerant flow to one or the other of the evaporatorsandthrough the respective expansion devices. Each evaporatorandgenerally is a heat exchanger that transfers heat from air passing over the evaporator,to refrigerant flowing through evaporator,, thereby cooling the air and causing the refrigerant to vaporize. A first evaporator fanmay be used to force air over first evaporatorand a second evaporator fanmay be used to force air over second evaporatoras illustrated. As such, cooled air is produced and supplied to refrigerated compartments,of refrigerator appliance. In certain embodiments, the evaporator fansandmay each be a variable speed evaporator fan-meaning the speed of each fan,may be controlled or set anywhere between and including, e.g., zero (0%) and one hundred percent (100%). The speed of each evaporator fanandmay be determined by controller, and communicated to each evaporator fan,by controller.

First evaporatormay be in communication with fresh food compartmentand second evaporatormay be in communication with freezer compartmentto provide cooled air to compartments,. In other embodiments, each evaporator,may be in communication with any suitable component of the refrigerator appliance. For example, in some embodiments, evaporatorormay be in communication with the ice maker, such as with an ice compartment(). From the selected evaporatoror(e.g., which is selected by the valveor is selected based on the position of the valve), refrigerant may flow back to and through compressor, which may be downstream of the selected evaporatoror, thus completing a closed refrigeration loop or cycle.

provides an exemplary graphof compressor EER (Energy Efficiency Ratio) curves at different evaporator temperatures. The noted temperatures are temperatures at the evaporators, e.g., which are generally cooler than the resultant temperature in the chilled chamber(s) downstream of the evaporators. As illustrated in, the horizontal axis provides exemplary compressor speeds, increasing from left to right, in Revolution Per Minute (RPM), and the vertical axis provides exemplary EER values, with efficiency increasing from the origin to the top of the graph on the page in.

Additionally, six exemplary EER curves for possible example evaporator temperatures are plotted in. As may be seen from, the compressor is generally more efficient at higher temperatures and slower speeds. Also as may be seen from, the slopes of the EER curves vary within each curve and from one curve to the next, e.g., such that changing compressor speeds within a same range of speeds may have differing effects on the achieved efficiency at different evaporator temperatures, and/or changing compressor speeds at a constant evaporator temperature (e.g., along a single EER curve in) may have differing effects on the achieved efficiency at different compressor speed ranges.

For one particular example that may be seen in, at an evaporator temperature of negative eight degrees (−8), decreasing the compressor speed from 4000 RPM to 3000 RPM provides a larger increase in efficiency than would decreasing the compressor speed from 2500 RPM to 1500 RPM, e.g., the same net change in speed (decrease by 1000 RPM) provides a greater efficiency benefit at some speed ranges than others.

As another example that may be seen in, decreasing compressor speed from 2500 RPM to 2000 RPM at an evaporator temperature of zero (0) degrees provides a larger increase in efficiency than decreasing compressor speed from 2500 RPM to 2000 RPM at an evaporator temperature of negative twelve (−12) degrees, e.g., the same speed change provides a greater efficiency benefit at some evaporator temperatures than others. It should be understood that the values noted herein and inare provided by way of example only for purposes of illustrating one or more possible embodiments out of numerous possible variations in temperature, speed, and/or efficiency.

provides a graph of EER curves, e.g., which may be the same EER curves described above with reference to, and exemplary operating points for two evaporators, e.g., a fresh food evaporator and a freezer evaporator, in a refrigerator appliance. For example, as illustrated in, one of the evaporators, e.g., a first evaporator or fresh food evaporator, may be operable at an evaporator temperature of negative eight (−8) degrees. In an exemplary operation, the operating pointfor fresh food mode (e.g., when valve() directs refrigerant to the fresh food evaporator) may thus correspond to a compressor speed of about 2500 RPM for one or more operation cycles (e.g., duty cycles), while the operating pointfor freezer mode (e.g., when valve() directs refrigerant to the freezer evaporator, which in the illustrated example is operable at an evaporator temperature of negative sixteen (−16) degrees) may thus correspond to a compressor speed of about 2800 RPM during a freezer portion of the same cycle(s). Also illustrated by way of example inare potential compressor speed adjustmentsand(which are speed decreases in this example, although speed increases are also possible as well as or instead of decreases) which may be determined, and/or of which one or other may be selected for implementation. For example, when a decrease in compressor speed (and a corresponding increase in duty cycle of the compressor, as will be discussed further below) is called for, the curve with the greatest slope to the left of the current operating point may be selected in order to provide the greatest efficiency benefit for the given speed decrease, or the least efficiency penalty in cases of a speed increase (which would correspond to the shallower slope to the right of the current operating point). Turning to the specific example first operating point, first compressor speed adjustment, second operating point, and second compressor speed adjustment, illustrated in, it may be seen that the slope to the left of operating pointis greater than the slope to the left of operating point. Thus, decreasing the compressor speed during operation of the second evaporator, e.g., during freezer mode, provides a greater efficiency benefit than a similar decrease in compressor speed during operation of the first evaporator, e.g., fresh food mode. Accordingly, the compressor speed adjustmentmay be prioritized over adjustment, e.g., adjustmentmay be implemented rather than adjustment, or both speeds may be adjusted based on a ratio of the slopes where a larger adjustment would be applied to the second operating point, in order to maximize the increase in efficiency from the speed decrease.

Turning now to, embodiments of the present disclosure may also include methods of operating a refrigerator appliance, such as the exemplary methodillustrated in. Such methods may be used with any suitable refrigerator appliance, for example but not limited to the exemplary refrigerator appliancedescribed above. Thus, the refrigerator appliance operated according to methodmay include a compressor within a sealed cooling system, e.g., compressorwithin sealed cooling system, as described above in reference to, and the compressor may be a variable speed compressor where the efficiency of the compressor varies with speed of the compressor and with the temperature of one or more evaporators coupled with the sealed cooling system, e.g., as described above in reference to.

As illustrated in, in some embodiments, methods according to the present disclosure such as methodmay include () operating the compressor for a first portion of a period of time. For example, operating the compressor for the first portion of the period of time may include operating the compressor in one or both of a fresh food mode and/or a freezer mode. In such embodiments, the first portion of the period of time may be the amount of time it takes to cool one or more chilled chambers of the refrigerator appliance, e.g., one or both of the fresh food chamberand the freezer chamber, to a setpoint temperature (or within a threshold of the setpoint temperature). The setpoint temperature may be a default predetermined value, e.g., that is preprogrammed into a memory of a controller such as the controller, or may be a user-selected value which is received via one or more user inputs of the refrigerator appliance. The setpoint temperature (and/or other ending temperature, such as within the threshold of the setpoint temperature) may be measured and/or detected by a temperature sensor in operative communication with the respective chilled chamber, e.g., temperature sensorfor fresh food chamberor temperature sensorfor freezer chamber.

Still referring to, methodmay further include () deactivating the compressor for a second portion of the period of time. For example, once the setpoint temperature in the chilled chamber (or each respective setpoint temperature for multiple chilled chambers in some embodiments) is reached, the compressor may be turned off for a period of time, e.g., until the temperature within the chilled chamber (or each chilled chamber) reaches an upper limit and further cooling is called for. In one exemplary operating cycle, e.g., where the refrigerator appliance includes at least two chilled chambers, e.g., at least the fresh food chamberand the freezer chamber, and one corresponding evaporator for each chilled chamber, the total period of time may include a fresh food cooling time, a freezer cooling time, and one or more down times during which the compressor is deactivated. For example, the cycle may include a fresh food cooling time, followed by a first down time, then a freezer cooling time and a second down time after the freezer cooling time. The cycle may then repeat after the second down time, e.g., may reiterate beginning with a next fresh food cooling time of a next operating cycle. In some embodiments, only one down time may be provided, e.g., either after the fresh food cooling time and before the freezer cooling time or after the freezer cooling time and before the fresh food cooling time of the next cycle, or no down time may be provided, e.g., the duty cycle of the compressor may be one hundred percent (100%).

As noted at () in, methodmay further include determining a duty cycle of the compressor based on a ratio of the first portion of the period of time to the period of time. For example, the first portion of the period of time may be a single amount of time over which the compressor is continuously activated, or may be a total of multiple amounts of time over which the compressor is activated, e.g., a sum of a fresh food cooling time and a freezer cooling time. The first portion and the second portion may add up to the total period of time. The total period of time may be the period of the duty cycle. For example, the period may be one hour, and the operating cycle may include fifteen minutes in fresh food mode (e.g., a fifteen-minute fresh food cooling time) and thirty minutes in freezer mode (e.g., a thirty-minute freezer cooling time), for a total first portion of the period of time of forty five minutes. Thus, the second portion of the period of time would be fifteen minutes, and the duty cycle, e.g., the ratio of the first portion of the period of time to the period of time, would be forty five minutes out of the sixty minute period-seventy five percent (75%). The foregoing values are provided by way of example only and without any limitation of the present disclosure, e.g., the period may be any suitable value in minutes and/or hours, and the duty cycle may vary as well.

Methodmay further include () comparing the determined duty cycle of the compressor to a predefined (e.g., predetermined or optimized) duty cycle or target duty cycle. The predefined duty cycle may be a duty cycle value which provides the desired cooling level, e.g., cools the one or more chilled chambers to the setpoint temperature within the total period of time, while also providing energy efficiency, e.g., by operating the compressor at a relatively low speed, e.g., at or about a lowest possible speed to complete the desired cooling within the total time period of the duty cycle. Thus, the predefined duty cycle may be between about eighty percent (80%) and about one hundred percent (100%), but not greater than 100% (it being understood that the compressor cannot be activated more than 100% of the time). For example, the predefined duty cycle may be between about ninety percent (90%) and about one hundred percent (100%), such as the predefined duty cycle may be about ninety five percent (95%). In some embodiments, the predefined duty cycle may be a range, such as a range from 95% to 100%, or other ranges of values described herein as opposed to a single target value.

In some embodiments, methodmay also include (), adjusting a speed of the compressor based on the comparison of the determined duty cycle to the predefined duty cycle. For example, when the determined duty cycle is less than the predefined duty cycle, the compressor speed may be reduced such that the cooling operation takes longer to reach the setpoint temperature, thereby lengthening the duty cycle. As another example, when the determined duty cycle is greater than the predefined duty cycle, the compressor speed may be increased such that the cooling operation reaches the setpoint temperature more quickly, thereby reducing, e.g., shortening, the duty cycle.

In some embodiments, the first portion of time may include a fresh food cooling time and a freezer cooling time, which may occur one directly after another or which may be separated by at least part of the second portion of time, e.g., a down time. In such embodiments, the compressor may be operated at a fresh food cooling speed during the fresh food cooling time and may be operated at a freezer cooling speed during the freezer cooling time, and such speeds may be the same speed or different speeds. In such embodiments, the adjusted speed of the compressor, e.g., which is adjusted at () as described above, may be at least one of the fresh food cooling speed and the freezer cooling speed.

For example, in embodiments where one of the fresh food cooling speed and the freezer cooling speed is adjusted, or when both are adjusted by varying degrees, exemplary methods may include determining which of the fresh food cooling speed and the freezer cooling speed to adjust, or the proportions by which each is adjusted, based on an efficiency of the compressor.

In some embodiments, the efficiency of the compressor may be determined from an EER, such as the exemplary EER curves described above in reference to. The data represented by the EER curves, such as the exemplary EER curves described above in reference to, may be stored in a memory of a controller of the refrigerator appliances, such as in a grid or tabular form. For example, the data in the fields of the table may represent points along each EER curve, and such data may be used to calculate slopes of each EER curve. The slope of the EER curve or curves (e.g., calculated from tabular data as noted) may be used to determine which speed, e.g., during which operating mode, to adjust (or the proportion of adjustment applied to two or more adjusted speeds).

In additional embodiments, the efficiency of the compressor may be determined from data collected in the field, e.g., by the particular refrigerator appliance unit during one or more operation cycles of the compressor therein. For example, one or more power meters, e.g., current sensor, wattage sensor, etc., may be provided in the refrigerator appliance and may be in communication with the controller of the refrigerator appliance to provide power consumption measurements to the controller. Thus, the power usage by the compressor during prior operations may be used to develop one or more bespoke EER curves for the particular refrigerator appliance unit, which may most accurately reflect the specific installation conditions and usage patterns of that particular refrigerator appliance unit. Accordingly, methods of operating the refrigerator appliance which include determining which of the fresh food cooling speed and the freezer cooling speed to adjust based on an efficiency of the compressor may also include measuring power consumption during operation of the compressor and determining the efficiency of the compressor based on the measured power consumption.

As mentioned above, in some embodiments, the first portion of time may include a fresh food cooling time and a freezer cooling time. In such embodiments, adjusting the speed of the compressor may include adjusting the speed of the compressor at the end of one of the fresh food cooling time and the freezer cooling time. For example, adjustments to the compressor speed may be determined and/or applied when a valve (e.g., valvedescribed above in reference to) changes position, e.g., when the cooling of the fresh food chamber or freezer chamber has just finished and the valve changes position to direct refrigerant to the other evaporator.

In some embodiments the first portion of time may include a fresh food cooling time and a freezer cooling time, e.g., where the compressor may be operated at a fresh food cooling speed during the fresh food cooling time and may be operated at a freezer cooling speed during the freezer cooling time. In such embodiments, adjusting the speed of the compressor may include adjusting both the fresh food cooling speed and the freezer cooling speed, whereby an average power draw of the compressor is minimized. For example, the total duty cycle, e.g., the total time in which the compressor is activated during the period of the duty cycle, may be unevenly divided between the fresh food mode and the freezer mode, such as the freezer mode may be longer, such as the freezer mode may be approximately one and a half times as long, or approximately twice as long, etc., as the fresh food mode. For example, the fresh food mode may be about 30% of the total period and the freezer mode may be about 65% of the total period, for a net duty cycle of about 95%. In embodiments where the fresh food time is not equal to the freezer time, a duty cycle ratio may be determined, e.g., about 1.5:1 or about 2:1 freezer to fresh food, as discussed. Similarly, a slope ratio may be determined based on the ratio of the slopes next to each operating point. Accordingly, some embodiments may include multiplying the slope ratio by the duty cycle ratio, in order to make the adjustment logic directly minimize average power draw of the compressor.

In embodiments where more than one compressor speed is adjusted, e.g., where the fresh food speed and the freezer speed are both adjusted, the speeds may be adjusted in the same direction, e.g., both (or all, if more than two) increased or both/all decreased. In additional embodiments, the speeds may be adjusted in opposite directions, such as when the relative slopes suggest or indicate a more efficient operating point exists. For example, if the slope to the left of a first operating point is much greater than the slope to the right of a second operating point, the compressor speed at the first operating point may be decreased while the compressor speed at the second operating point is increased, where the efficiency penalty from increasing the speed at the second operating point is relatively small (e.g., as indicated by the slope to the right of the operating point) and is therefore offset by the relatively large efficiency gain from decreasing the compressor speed at the first operating point (e.g., as indicated by the slope to the left of the first operating point).

Aspects of the present disclosure relate to an adaptive control scheme that actively targets and seeks a given total duty cycle, such as a range from 95-100%, while balancing the FF and FZ compressor speeds to minimize energy consumption dynamically using compressor efficiency data, such as EER/Speed curve slopes and/or empirical data gathered from one or more power meters during prior operating cycles of the specific refrigerator unit. The duty cycle may be divided into both fresh food (FF) and freezer (FZ) duty cycles, which run semi-independently (e.g., the duty cycles may be 65% FZ+30% FF=95% total). Adjustments may occur when the valve changes position, having just finished cooling the FF or FZ. Additionally, adjustments may occur when “timeout” event take place or when the opposite compartment reaches an excessively high temperature before cooling is completed in the current compartment. In such cases, e.g., when the opposite compartment reaches an excessively high temperature before cooling is completed in the current compartment, this may indicate that the speed of the current compartment mode (FF mode or FZ mode) should be increased the next time. The refrigerator does not significantly impact the quick pull-down after receiving new groceries or excessive door openings (higher speeds), as it maintains the same basic grid control.