Refrigeration device and method for operating a refrigeration device

Abstract

The invention relates to a method for operating a refrigeration device, having the steps of detecting the actual temperature in a storage compartment of the refrigeration device, ascertaining a deviation of the actual temperature from a target temperature, and calculating a target rotational speed of a compressor by means of a controller on the basis of the deviation of the actual temperature from the target temperature. The method additionally has the step of detecting a first control limiting case in which the controller calculates a target rotational speed that is higher than the maximum rotational speed of the compressor, a second control limiting case in which the controller calculates a target rotational speed that is lower than the minimum rotational speed of the compressor, or a third control limiting case in which an increase in the actual temperature in the storage compartment is expected and for which the controller calculates a target rotational speed that is higher than the current rotational speed of the compressor. If the first control limiting case is detected, the compressor is operated at a constant first rotational speed. If the second control limiting case is detected, the compressor is operated at a constant second rotational speed which is lower than the first rotational speed. If the third control limiting cases detected, the compressor is operated at a constant third rotational speed which is lower than or equal to the first rotational speed and higher than the second rotational speed. If none of the control limiting cases are detected, the compressor is operated at the target rotational speed calculated by the controller.

Description

[0001] Refrigeration device and method for operating a refrigeration device

[0002] TECHNICAL FIELD

[0003] The present invention relates to a refrigeration appliance, in particular a household refrigeration appliance such as a refrigerator, a freezer or a freezer chest or a fridge-freezer combination, and a method for operating a refrigeration appliance.

[0004] STATE OF THE ART

[0005] In household refrigeration appliances, a refrigerant is circulated through a refrigerant circuit with the aid of a compressor to remove heat from a storage compartment. To adjust the actual temperature in the storage compartment to a desired target temperature, the refrigerant mass flow circulated by the compressor can be varied, for example, by varying the compressor's speed. Operating the compressor at a variable speed also offers advantages in terms of energy efficiency and reducing noise emissions from the refrigeration appliance.

[0006] Therefore, various methods for controlling a speed of a compressor of a refrigerant circuit are described in the prior art, e.g. in US 2022 / 0260 300 A1, US 5255 530 A, US 6 769265 B1 or KR 10-0208355 B1.

[0007] SUMMARY OF THE INVENTION

[0008] It is one of the objects of the present invention to provide improved solutions for the operation of a refrigeration appliance having a compressor operated at a variable speed, in particular solutions which improve the control of the speed of the compressor.

[0009] This object is achieved according to the invention by a method having the features of claim 1 and by a refrigeration device having the features of claim 12. A method for operating a refrigeration device, in particular a household refrigeration device, comprises detecting an actual temperature in a storage compartment of the refrigeration device, determining a deviation of the actual temperature from a target temperature and calculating a target speed of a compressor, which circulates refrigerant in a refrigerant circuit in order to dissipate heat from the storage compartment, by a controller depending on the determined deviation of the actual temperature from the target temperature such that the target speed of the compressor is increased when the actual temperature is greater than the target temperature and is reduced when the actual temperature is less than the target temperature.The method further comprises detecting a first control limit case in which the controller calculates a target speed of the compressor that is greater than a maximum speed of the compressor, a second control limit case in which the controller calculates a target speed of the compressor that is less than a minimum speed of the compressor, or a third control limit case in which an increase in the actual temperature in the storage compartment is expected, for which the controller calculates a target speed of the compressor that is greater than a current speed of the compressor. If the first control limit case is detected, the compressor is operated at a constant first speed until the detected actual temperature reaches the target temperature or until a predetermined first time period has elapsed.If the second control limit case is detected, the compressor is operated at a constant second speed that is lower than the first speed until the detected actual temperature reaches the setpoint temperature or until a predetermined second time period has elapsed. If the third control limit case is detected, the compressor is operated at a constant third speed that is less than or equal to the first speed and greater than the second speed until the detected actual temperature reaches the setpoint temperature or until a predetermined third time period has elapsed. If none of the control limit cases is detected, the compressor is operated at the setpoint speed calculated by the controller. The first, second and third time periods can be the same or different and can, for example, range between one minute and ten minutes.

[0010] According to a second aspect of the invention, a refrigeration appliance, in particular a household refrigeration appliance such as a refrigerator, a freezer or a chest freezer or a fridge-freezer combination, comprises a storage compartment for accommodating refrigerated goods, a refrigerant circuit with a compressor for circulating refrigerant, wherein the refrigerant circuit is designed to absorb heat from the storage compartment by evaporating refrigerant and to release it to the environment by condensing the refrigerant, a temperature sensor for detecting an actual temperature in the storage compartment and a control unit which is connected to the temperature sensor and the compressor in a signal-conducting manner and has a controller for calculating a target speed of the compressor based on a deviation of the actual temperature from a target temperature. The control unit is designed to cause the refrigeration appliance to carry out a method according to the first aspect of the invention.

[0011] One idea underlying the invention is to operate the compressor at a constant speed in certain situations during operation of the refrigeration appliance, instead of with a variable speed control. In situations in which the actual temperature in the storage compartment is below or above the target temperature for a longer period of time, e.g. over a period of 10 to 30 minutes, or in situations in which the actual temperature deviates from the target temperature by more than a predetermined limit value, e.g. by more than 4 °C, or in situations in which it is expected that the actual temperature will subsequently deviate from the target temperature by more than the limit value or for longer than the specified period, the controller calculates a speed that is above or below the minimum speed at which the compressor can be operated, or deviates significantly, e.g. by more than 50 percent, from the current actual speed of the compressor.According to the invention, however, in these situations the compressor is operated at a constant speed, either over a predetermined period of time or until the actual temperature again corresponds to the target temperature.

[0012] This offers the advantage of more stable and faster compartment temperature control with less variation in compressor speed. In particular, the compressor speed fluctuates less, which also further reduces noise emissions.

[0013] Advantageous refinements and developments emerge from the dependent claims, which refer back to the independent claims, in conjunction with the description. According to some embodiments, the controller can be a PI controller or a PID controller. Particularly in controllers with an integral component, it is advantageous to operate the compressor at a constant speed in the aforementioned control limit cases, since this can reduce oscillations in the speed curve that would result from the integral component of the control.

[0014] According to some embodiments, it can be provided that the controller receives the actual temperature and the target temperature as input variables, wherein a value corresponding to the target temperature is supplied to the controller as the actual temperature when the first, second, or third control limit case is detected. This means that when the control limit cases occur, the controller is not deactivated; instead, its input receives a constant temperature value corresponding to the target temperature. Consequently, the controller calculates a speed for the compressor that is not above the maximum or below the minimum speed, and the integral component of the controller becomes zero. This further reduces oscillations in the speed curve specified by the controller after the target temperature has been reached or after the predetermined period of time has elapsed.This results in more stable compressor speed control and prevents overshoots in the actual temperature curve. This also leads to lower compressor energy consumption, reduced noise emissions, and an extended compressor service life.

[0015] According to some embodiments, the method may include detecting an activation state of a heating device of an evaporator thermally coupled to the storage compartment, wherein the third control limit case is detected when the heating device is activated to defrost the evaporator and is deactivated after defrosting has ended. Defrosting the evaporator using the heating device results in the actual temperature detected in the storage compartment rising at least temporarily, since, on the one hand, heat dissipation from the storage compartment via the evaporator is interrupted and, on the other hand, heat is introduced into the storage compartment by the heating device. The temperature rise can either be detected immediately, and the controller can calculate a correspondingly high speed above the maximum speed, which would correspond to the second control limit case, or the temperature rise can be detected with a time delay.Particularly in the latter situation, it can be advantageous to operate the compressor at a constant, high speed as soon as the end of the defrosting process is detected, i.e. when the heating device is deactivated, in order to quickly reach the target temperature again and at the same time to avoid the compressor being operated at too high a speed for longer than necessary because the controller calculates a target speed that is higher than the maximum speed and only calculates values ​​for the target speed that are lower than the maximum speed after a delay when the target temperature is reached.

[0016] According to some embodiments, the refrigerant circuit may comprise an evaporator thermally coupled to the storage compartment, having a heating device for defrosting the evaporator. The heating device is signal-conductingly connected to the control unit, and the control unit is configured to activate and deactivate the heating device for defrosting the evaporator. The evaporator may, in particular, be a finned evaporator arranged in an evaporator chamber fluidically connected to the storage compartment.

[0017] According to some embodiments, it can be provided that, while the heating device is activated, a refrigerant mass flow conveyed by the compressor is bypassed by the evaporator or the compressor is deactivated. For example, a bypass line bypassing the evaporator and a bypass valve can be provided in the refrigerant circuit, wherein the bypass valve is arranged and switchable in such a way as to divide the refrigerant mass flow between the evaporator and the bypass line, in particular in such a way that the refrigerant mass flow is guided either through the evaporator or through the bypass line. The bypass line can, for example, lead to another evaporator that is thermally coupled to an optional additional storage compartment of the refrigeration device.

[0018] According to some embodiments, the method may include detecting a position of a door closing the storage compartment, wherein the third control limit case is detected when an open position of the door is detected. Accordingly, according to some embodiments, the refrigeration device may comprise a door that is movable between a closed position, in which it covers an access opening of the storage compartment, and an open position, in which it at least partially exposes the access opening, and a door sensor that is connected to the control unit in a signal-conducting manner and is configured to detect the position of the door.

[0019] According to some embodiments, when the second control limit case is detected, a refrigerant mass flow delivered by the compressor is at least partially bypassed by an evaporator thermally coupled to the storage compartment in order to reduce heat dissipation from the storage compartment. In this way, the time required to raise the excessively low actual temperature to the target temperature and thus the time during which the compressor is operated at a constant, low speed or second speed is further reduced. For example, in this case, the compressor can continue to supply refrigerant to a further evaporator, which is thermally coupled to an optional additional storage compartment of the refrigeration device.

[0020] According to some embodiments, the first speed may be the maximum speed of the compressor. Accordingly, the compressor may be operated at maximum speed in the first and third control limit cases. This offers the advantage that the desired target temperature is quickly reached if the actual temperature is greater than the target temperature.

[0021] According to some embodiments, it can be provided that the second speed is zero or the minimum speed of the compressor. Accordingly, it can be provided that the compressor is operated at minimum speed in the second control limit case. This offers the advantage that the desired target temperature is quickly reached if the actual temperature is lower than the target temperature. It is also conceivable that the compressor is switched off in this case, i.e., operated at zero speed, which reduces energy consumption.

[0022] According to some embodiments, the third speed may be less than or equal to the maximum speed and greater than the minimum speed of the compressor. For example, the third speed may be at least 25 percent greater than the current actual speed of the compressor. Thus, in cases where an increase in the actual temperature is expected, the previous speed of the compressor is increased by a predetermined value. The features and advantages disclosed herein in connection with one aspect of the invention are also disclosed for the respective other aspect, and vice versa.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention is explained below with reference to the figures of the drawings. The figures show:

[0025] Fig. 1 is a simplified, schematic view of a refrigeration device according to an embodiment of the invention;

[0026] Fig. 2 is a simplified, schematic block diagram of a refrigeration device according to an embodiment of the invention; and

[0027] Fig. 3 is a flowchart of a method for operating a refrigeration device according to an embodiment of the invention.

[0028] In the figures, the same reference symbols denote identical or functionally identical components, unless otherwise stated.

[0029] DETAILED DESCRIPTION OF EMBODIMENTS

[0030] Fig. 1 shows, by way of example and purely schematically, a refrigeration appliance 100 in the form of a refrigerator. However, the present invention is not limited to a refrigerator, but can also be used in a freezer or chest freezer, a refrigerator-freezer combination, or generally in a household refrigeration appliance or other refrigeration appliance.

[0031] The refrigeration appliance 100 shown as an example in Fig. 1 has a body 110 which defines a storage compartment 1. The storage compartment 1 is accessible through an access opening 10 formed in the body 110. A door 5 which is movable between an open position and a closed position can be mounted on the body 110. Fig. 1 shows the open position of the door purely as an example. In the open position, the door 5 at least partially exposes the access opening 10. In the closed position, the door 5 covers the access opening 10. The storage compartment 1 is provided for storing refrigerated goods such as food, beverages, medicines or the like in order to expose them to a specific temperature environment.

[0032] Fig. 2 shows a schematic block diagram of the refrigeration device 100. As shown in Fig. 2, the refrigeration device 100 generally comprises a storage compartment 1, a refrigerant circuit 2, a control unit 3, a temperature sensor 4 and, optionally, a door sensor 6.

[0033] As already explained above, storage compartment 1 serves to accommodate refrigerated goods. Optionally, an evaporator chamber 11 can be provided, which is fluidly connected to storage compartment 1, e.g., via openings 12, 13.

[0034] As shown in Fig. 2, the refrigerant circuit 2 comprises an evaporator 21, a compressor 22, and a condenser 23. Optionally, a heating device 24 may also be provided. Also optionally, the refrigerant circuit 2 may comprise a fan 25.

[0035] The evaporator 21 can be, for example, a compact or finned evaporator. The evaporator 21 can, for example, be arranged in the evaporator chamber 11, as schematically shown in Fig. 2. The optional fan 25 can also be positioned in the evaporator chamber 11 and configured to direct an air flow over the evaporator 21 and circulate it between the storage compartment 1 and the evaporator chamber 11.

[0036] A suction port of the compressor 22 is connected to an outlet of the evaporator 21. Furthermore, a pressure port of the compressor 22 is connected to the condenser 23. An outlet of the condenser 23 is connected to an inlet of the evaporator 21, with a throttle (not shown) for expanding the refrigerant being arranged between the condenser 23 and the evaporator 21.

[0037] The refrigerant evaporates in the evaporator 21, absorbing heat from the storage compartment 1. The compressor 22 draws in the gaseous refrigerant, compresses it, and feeds it to the condenser 23, where it condenses, releasing heat to the environment. From the condenser 23, the liquid refrigerant flows back into the evaporator 21 via the throttle. The compressor 22 thus circulates the refrigerant in the refrigerant circuit. The mass flow of the refrigerant can be varied, for example, by changing the speed at which the compressor 22 operates.

[0038] The optional heating device 24 is provided on the evaporator 21 and is designed to supply heat to the evaporator 21 in order to melt ice that may form on an outer surface of the evaporator 21 and thus defrost the evaporator 21.

[0039] The temperature sensor 4 can be arranged in the storage compartment 1 of the refrigeration device 100, as schematically shown in Fig. 2. Generally, the temperature sensor 4 is designed to detect an actual temperature in the storage compartment 1. The temperature sensor 4 can be, for example, a PTC element, a thermocouple, or the like.

[0040] The door sensor 6 is designed to detect the position of the door 5. The door sensor 6 is thus capable of outputting a signal from which it can be determined whether the door 5 is in the open or closed position. The door sensor 6 can be, for example, an optical sensor, a proximity switch, or a simple electrical switch.

[0041] The control unit 3 is generally an electronic control unit. For example, the control unit 3 can have a processor, e.g., in the form of a CPU, an FPGA, an ASIC, or the like, and a data memory, in particular a non-volatile memory, e.g., in the form of a flash memory, an SD memory, an EEPROM, or the like. The data memory is readable by the processor and can, for example, store software that is executable by the processor and causes it to generate output signals based on input signals.

[0042] As shown schematically in Fig. 2, the control unit 3 has an input interface 31, an output interface 32, a controller 35 and an evaluation unit 33. The input interface 31 and the output interface 32 can be designed as wired interfaces, e.g. as BUS interfaces, or wireless interfaces, e.g. as Bluetooth interfaces, NFC interfaces or the like. As shown schematically in Fig. 2, the temperature sensor 4 and the optional door sensor 6 are connected to the input interface 31 in a signal-conducting manner. The compressor 22 is connected to the output interface 32 in a signal-conducting manner. If necessary, the optional heating device 24 is also connected to the output interface 32. Optionally, the fan 25 can also be connected to the output interface 32.

[0043] The controller 35 and the evaluation unit 33 can be implemented at least partially as software. The controller 35 can be, for example, a PI controller or a PID controller. The controller 35 receives the actual temperature measured by the temperature sensor 4 and a target temperature of the storage compartment 1 as input variables. The target temperature can be set by a user, for example, via a user interface (not shown) and transmitted to the input interface 31. Based on a deviation of the actual temperature from the target temperature, the controller 35 calculates a target speed of the compressor 22.

[0044] The evaluation unit 33 receives the target speed calculated by the controller 35 as well as the position of the door 5 detected by the temperature sensor 4 and, if applicable, the position of the door 5 detected by the door sensor 6. Based on these inputs, it outputs a control signal to the output interface 32 in order to operate the compressor 22 at the target speed calculated by the controller 35, or at a constant first speed, or at a constant second speed that is lower than the first speed. Furthermore, the evaluation unit 33 can also receive the current actual speed of the compressor 22. The evaluation unit 33 can also be configured to supply the controller 35 with a temperature value for the actual temperature. Furthermore, the evaluation unit 33 can be configured to output a control signal to the heating device 24 in order to activate and deactivate it.

[0045] Fig. 3 schematically shows the sequence of a method M for operating a refrigeration device 100. The control unit 3 of the refrigeration device 100 described above is designed to cause the refrigeration device 100 to execute this method M. The method M is therefore explained below with reference to the refrigeration device 100 described above.

[0046] In step M1, the actual temperature in storage compartment 1 of refrigeration device 100 is detected using temperature sensor 4. Optionally, in step M1, an activation state of heating device 24 can also be detected. This can be done, for example, using evaluation unit 33, which writes the current activation state to a data memory (not shown). Also optionally, in step M1, the position of door 5 can be detected using door sensor 6.

[0047] In step M2, a deviation between the actual temperature and the target temperature is determined. This can be done, for example, by controller 35 or by evaluation unit 33.

[0048] In step M3, the controller 35 calculates the target speed of compressor 22. To do this, controller 35 calculates the target speed of compressor 22 based on the determined deviation of the actual temperature from the target temperature. Generally, the controller calculates an increase in the target speed of compressor 22 if the actual temperature is higher than the target temperature and a decrease in the target speed if the actual temperature is lower than the target temperature.

[0049] In step M4, the presence of a control boundary case is detected with the aid of the evaluation unit 33. A first control boundary case occurs when the controller 35 calculates a target speed of the compressor 22 that is greater than a maximum speed of the compressor 22. A second control boundary case occurs when the controller 35 calculates a target speed of the compressor 22 that is less than a minimum speed of the compressor 22. To detect the first and second control boundary cases, the evaluation unit 33 can compare the target speed calculated by the controller 35 with one of the minimum speed and the maximum speed at which the compressor 22 can be operated.

[0050] A third control limit case occurs when an increase in the actual temperature in storage compartment 1 is expected, for which the controller 35 calculates a target speed of the compressor 22 that is greater than the current actual speed of the compressor 22. A third control limit case can occur in particular as a result of defrosting the evaporator 21 with the aid of the heating device 24 or as a result of opening the door 5, since in these situations a significant increase in the actual temperature is to be expected. The third control limit case can thus be detected by the evaluation unit 33, for example, when the heating device 24 is activated to defrost the evaporator 21 and is deactivated after defrosting is complete. While the heating device 24 is activated. The evaluation unit 33 can also detect the third control limit case when the door sensor 6 detects the open position of the door 5.In these cases, it is expected that the temperature in storage compartment 1 will rise, which the controller 35 would compensate for by calculating a target speed that is greater than the actual speed.

[0051] If the presence of the first control limit case is detected in step M4, the evaluation unit 33 outputs a target speed which corresponds to a constant first speed and the method M proceeds to step M5, as shown in Fig. 3 by the symbol "*". In step M5, the compressor 22 is operated at the constant first speed. The first speed can, for example, correspond to the maximum speed of the compressor 22. Step M5 is carried out until the detected actual temperature reaches the target temperature or until a predetermined first time period has elapsed. The method M then proceeds to step M7, in which the compressor 22 is operated at the target speed calculated by the controller 35.

[0052] If the presence of the second control limit case is detected in step M4, the evaluation unit 33 outputs a target speed which corresponds to a constant second speed and the method M proceeds to step M6, as represented in Fig. 3 by the symbol "#". In step M6, the compressor 22 is operated at the constant second speed. The second speed is generally lower than the first speed and can, for example, be the minimum speed of the compressor or a speed equal to zero. Step M6 is executed until the detected actual temperature reaches the target temperature or until a predetermined second time period has elapsed. The method M then proceeds to step M7.

[0053] If the presence of the third control limit case is detected in step M4, the evaluation unit 33 outputs a target speed that corresponds to a constant third speed, and the method M proceeds to step M8, as represented by the symbol in Fig. 3. In step M8, the compressor 22 is operated at the constant third speed. The third speed is less than or equal to the first speed but greater than the second speed. For example, the third speed can be less than or equal to the maximum speed and greater than the minimum speed of the compressor 22. Optionally, the third speed can be at least 25 percent greater than the current speed of the compressor 22. For example, the evaluation unit 33 can calculate the target speed based on the current speed or output a value for the target speed that is stored in a memory.Step M8 is executed until the detected actual temperature reaches the target temperature or until a predetermined third time period has elapsed. Method M then proceeds to step M7, in which compressor 22 is operated at the target speed calculated by controller 35. The first, second, and third time periods can be the same or different, for example. In general, the first, second, and third time periods can range between 1 minute and 10 minutes, for example. Method M then proceeds to step M7.

[0054] If none of the control limit cases is detected in step M4, as shown in Fig. 3 by the symbol “+”, the method M goes directly to step M7.

[0055] During steps M5, M6, and M8, the evaluation unit 33 can optionally supply a value corresponding to the target temperature to the controller 35 as the actual temperature. In this way, in the case of a PI controller or a PID controller, the integral component becomes zero. This prevents or at least shortens the settling of the controller 35 after the completion of the respective step M5 or M6.

[0056] If the second control limit case is detected in step M4, a refrigerant mass flow delivered by the compressor 22 can optionally be directed at least partially past the evaporator 21 in step M6 in order to reduce heat dissipation from the storage compartment 1. For example, the control unit 3, in particular the evaluation unit 33, can control a control valve (not shown) to direct the refrigerant flow past the evaporator 21 via a bypass line (not shown). This can also occur during the activation of the heating device 24. In this case, the control unit 3, in particular the evaluation unit 33, can optionally also deactivate the compressor 22.

[0057] An advantage of the described method M is that in cases where the controller 35 calculates target speeds that are above the maximum or below the minimum speed at which the compressor 22 can be operated, the compressor 22 is operated at a constant speed.

[0058] Although the present invention has been explained above using exemplary embodiments, it is not limited thereto, but can be modified in many ways. In particular, combinations of the above exemplary embodiments are also conceivable.

[0059] REFERENCE SYMBOL

[0060] 1 storage compartment

[0061] 2 Refrigerant circuit

[0062] 3 Control unit

[0063] 4 Temperature sensor

[0064] 5 doors

[0065] 6 Door sensor

[0066] 10 Access opening

[0067] 11 Evaporator chamber

[0068] 21 evaporators

[0069] 22 compressors

[0070] 23 Condenser

[0071] 24 Heating device

[0072] 25 fans

[0073] 31 Input interface

[0074] 32 Output interface

[0075] 33 Evaluation unit

[0076] 35 controllers

[0077] 100 refrigeration appliances

[0078] 110 Corpus

[0079] M procedure

[0080] M1-M7 process steps

Claims

PATENT CLAIMS 1. Method (M) for operating a refrigeration appliance (100), in particular a household refrigeration appliance, comprising: Detecting (M1) an actual temperature in a storage compartment (1) of the refrigeration device (100); determining (M2) a deviation of the actual temperature from a target temperature; Calculating (M3) a target speed of a compressor (22), which circulates refrigerant in a refrigerant circuit (2) in order to dissipate heat from the storage compartment (1), by a controller (35) depending on the determined deviation of the actual temperature from the target temperature such that the target speed of the compressor (22) is increased if the actual temperature is greater than the target temperature and is reduced if the actual temperature is less than the target temperature; Detecting (M4) a first control limit case in which the controller (35) calculates a target speed that is greater than a maximum speed of the compressor (22), a second control limit case in which the controller (35) calculates a target speed that is less than a minimum speed of the compressor (22), or a third control limit case in which an increase in the actual temperature in the storage compartment (1) is expected, for which the controller (35) calculates a target speed that is greater than a current speed of the compressor (22); and Operating (M5) the compressor (22) at a constant first speed until the detected actual temperature reaches the target temperature or until a predetermined first time period has elapsed when the first control limit case is detected, or Operating (M6) the compressor (22) at a constant second speed which is lower than the first speed until the detected actual temperature reaches the target temperature or until a predetermined second time period has elapsed when the second control limit case is detected, Operating (M8) the compressor (22) at a constant third speed which is less than or equal to the first speed and greater than the second speed until the detected actual temperature reaches the target temperature or until a predetermined third time period has elapsed if the third control limit case is detected, and otherwise Operating (M7) the compressor (22) at the target speed calculated by the controller (35).

2. Method (M) according to claim 1, wherein the controller (35) is a PI controller or a PID controller.

3. Method (M) according to claim 2, wherein the controller (35) receives the actual temperature and the target temperature as input variables, and wherein a value corresponding to the target temperature is supplied to the controller (35) as the actual temperature when the first, the second or the third control limit case is detected.

4. Method (M) according to one of the preceding claims, additionally comprising: detecting (M1) an activation state of a heating device (24) of an evaporator (21) thermally coupled to the storage compartment (1), wherein the third control limit case is detected when the heating device (24) is activated to defrost the evaporator (21) and is deactivated after defrosting has ended.

5. Method (M) according to claim 4, wherein while the heating device (24) is activated, a refrigerant mass flow conveyed by the compressor (22) is passed past the evaporator (21) or the compressor (22) is deactivated.

6. Method (M) according to one of the preceding claims, additionally comprising: detecting (M1) a position of a door (5) closing the storage compartment (1), wherein the third control limit case is detected when an open position of the door (5) is detected.

7. Method (M) according to one of the preceding claims, wherein, when the second control limit case is detected, a refrigerant mass flow conveyed by the compressor (22) is at least partially guided past an evaporator (21) thermally coupled to the storage compartment (1) in order to reduce heat dissipation from the storage compartment (1).

8. Method (M) according to one of the preceding claims, wherein the first speed is the maximum speed of the compressor (22).

9. Method (M) according to one of the preceding claims, wherein the second speed is zero or the minimum speed of the compressor (22).

10. Method (M) according to one of the preceding claims, wherein the third speed is less than or equal to the maximum speed and greater than the minimum speed of the compressor (22).

11. Method (M) according to one of the preceding claims, wherein the third speed is at least 25 percent greater than the current speed of the compressor (22).

12. A refrigeration appliance (100), in particular a household refrigeration appliance, comprising: a storage compartment (1) for receiving refrigerated goods; a refrigerant circuit (2) with a compressor (22) for circulating refrigerant, wherein the refrigerant circuit (2) is designed to absorb heat from the storage compartment (1) by evaporating refrigerant and to release it to the environment by condensing the refrigerant; a temperature sensor (4) for detecting an actual temperature in the storage compartment (1); and a control unit (3) which is connected to the temperature sensor (4) and the compressor (22) in a signal-conducting manner and has a controller (35) for calculating a target speed of the compressor (22) based on a deviation of the actual temperature from a target temperature; characterized in that the control unit (3) is designed to cause the refrigeration appliance (100) to carry out a method (M) according to one of the preceding claims.

13. Refrigeration device (100) according to claim 12, wherein the refrigerant circuit (2) has an evaporator (21) thermally coupled to the storage compartment (1) with a heating device (24) for defrosting the evaporator (21), wherein the heating device (24) is connected to the control unit (3) in a signal-conducting manner, and the control unit (3) is designed to activate and deactivate the heating device (24) for defrosting the evaporator (21).

14. Refrigeration appliance (100) according to claim 13, wherein the evaporator (21) is a finned evaporator which is arranged in an evaporator chamber (11) fluidically connected to the storage compartment (1).

15. Refrigeration appliance (100) according to one of claims 12 to 14, additionally comprising: a door (5) which is movable between a closed position, in which it covers an access opening (10) of the storage compartment (1), and an open position, in which it at least partially exposes the access opening (10); and a door sensor (6) which is connected to the control unit (3) in a signal-conducting manner and is designed to detect the position of the door (5).

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