Evaporator defrosting judgment method and frequency conversion refrigerator

Abstract

The invention provides an evaporator defrosting judgment method and a frequency conversion refrigerator, and the method comprises the steps that frequency conversion driving is detected to output current change information, and the current change information is obtained through compressor load change; a reference current value is obtained, the current deviation rate is calculated, the reference current value is determined based on the environment temperature and the rotating speed of the compressor, and the current deviation rate is calculated through the reference current value and the current change information; if the current deviation ratio is larger than a current deviation threshold value, a defrosting instruction is output, and the defrosting instruction is used for triggering a defrosting condition. According to the method, the output current is collected in real time through variable frequency driving, the frosting condition of the evaporator can be detected in real time through the change of the output current, the influence of the humidity of articles stored by a user, the number of the articles, the door opening time and other conditions is avoided, the frosting condition of the evaporator can be reflected, and the problem that defrosting judgment through a defrosting judgment mechanism is inaccurate is solved.

Description

Technical Field

[0001] This application relates to the technical field of refrigeration equipment, and particularly to a method for judging defrosting of an evaporator and a variable-frequency refrigerator. Background Art

[0002] Frost formation on the surface of the evaporator of a variable-frequency air-cooled refrigerator will hinder air flow and reduce heat exchange efficiency. A defrosting program is required to remove the frost layer to maintain refrigeration performance. Differences in the humidity, storage capacity of the items inside the refrigerator, and user usage habits lead to dynamic changes in the frost formation rate. Accurately judging the defrosting timing requires balancing the energy consumption control and the temperature stability requirements, which poses real-time and adaptability requirements for the defrosting judgment mechanism.

[0003] The defrosting judgment mechanism includes a timed defrosting method based on preset rules and a method for detecting the frost layer thickness through an optical or capacitive sensor. The timed defrosting method based on preset rules sets a fixed defrosting cycle or a compressor cumulative operation time threshold according to experience, and the method for detecting the frost layer thickness through an optical or capacitive sensor collects the frost layer data in real time through the sensor and triggers the defrosting action.

[0004] The mechanism based on the preset defrosting rules needs to be tested and parameter-adjusted multiple times for different refrigerator models, and the fixed thresholds in the rules cannot adapt to the frost formation rate fluctuations caused by differences in the humidity of the stored items and the door opening frequency during actual use, resulting in premature or late defrosting; for the detection mechanism using a sensor, the sensor is prone to performance degradation in a low-temperature and high-humidity environment, affecting the detection stability. In summary, the defrosting judgment through the defrosting judgment mechanism is inaccurate. Summary of the Invention

[0005] This application provides a method for judging defrosting of an evaporator and a variable-frequency refrigerator to solve the problem of inaccurate defrosting judgment through the defrosting judgment mechanism.

[0006] In a first aspect, this application provides a method for judging defrosting of an evaporator, including:

[0007] Detect the variable-frequency drive to output current change information, where the current change information is the information obtained through the change of the compressor load;

[0008] Obtain a reference current value and calculate a current deviation rate. The reference current value is determined based on the ambient temperature and the compressor speed, and the current deviation rate is calculated through the reference current value and the current change information;

[0009] If the current deviation rate is greater than the current deviation threshold, output a defrosting instruction, where the defrosting instruction is used to trigger the defrosting condition.

[0010] In some feasible embodiments, the obtaining of the reference current value includes:

[0011] Obtain the ambient temperature and divide the ambient temperature into preset temperature intervals;

[0012] Based on the preset temperature intervals, calibrate a reference current value, where the reference current is the reference current of the variable frequency drive output corresponding to the compressor speed in the non-frosted state of the evaporator.

[0013] In some feasible embodiments, calculating the current deviation rate includes:

[0014] Generate a mapping relationship based on the reference current value, the preset temperature intervals, and the compressor speed;

[0015] Obtain the ambient temperature and the compressor speed, where the ambient temperature is the current ambient temperature and the compressor speed is the current compressor speed;

[0016] Determine the preset temperature interval based on the ambient temperature;

[0017] Based on the preset temperature interval and the compressor speed, match the reference current value according to the mapping relationship.

[0018] In some feasible embodiments, calculating the current deviation rate includes:

[0019] Obtain the variable frequency drive output current;

[0020] Based on the variable frequency drive output current and the reference current value, calculate the difference;

[0021] Calculate the current deviation rate, where the current deviation rate is the ratio of the difference to the reference current value.

[0022] In some feasible embodiments, the current deviation threshold includes a first deviation rate threshold;

[0023] If the current deviation rate is greater than the current deviation threshold, output a defrosting instruction, including:

[0024] If the current deviation rate is greater than the first deviation rate threshold, obtain a first preset duration, where the first preset duration is the duration for which the current deviation rate is greater than the first deviation rate threshold;

[0025] If the first preset duration is greater than the duration threshold, generate a first alarm signal, where the first alarm signal indicates that the frost thickness on the evaporator is a first thickness.

[0026] In some feasible embodiments, the current deviation threshold includes a second deviation rate threshold;

[0027] If the current deviation rate is greater than the current deviation threshold, output a defrosting instruction, including:

[0028] If the current deviation rate is greater than the second deviation rate threshold and the first preset duration is greater than the duration threshold, a second alarm signal and a defrosting instruction are generated. The second alarm signal indicates that the frosting thickness of the evaporator is a second thickness, and the second thickness is greater than the first thickness.

[0029] In some feasible embodiments, the method further includes:

[0030] In response to the defrosting instruction, control the defrosting heater to operate and obtain the temperature of the evaporator;

[0031] When the temperature of the evaporator is greater than or equal to the preset defrost termination temperature, record the operating time of the compressor and obtain a reference current value based on the operating time of the compressor.

[0032] In some feasible embodiments, the detecting the variable frequency drive to output current change information includes:

[0033] Based on field-oriented control, collect the three-phase current signals of the motor;

[0034] Transform the three-phase current signals to convert them into a direct-axis current component and a quadrature-axis current component;

[0035] Based on a vector control algorithm, calculate the motor output torque through the direct-axis current component and the quadrature-axis current component;

[0036] According to the torque, identify the change in the compressor load to output current change information.

[0037] In some feasible embodiments, the obtaining the reference current value further includes:

[0038] Obtain humidity data and set a humidity range;

[0039] Match the humidity data to the humidity range and call a humidity compensation coefficient according to the humidity range;

[0040] Generate a corrected reference current value, where the corrected reference current value is the product of the humidity compensation coefficient and the reference current value.

[0041] In a second aspect, the present application provides a variable frequency refrigerator, including:

[0042] A controller configured to:

[0043] Detect the variable frequency drive to output a current change, where the current change is caused by a change in the compressor load, and the current deviation rate is calculated through the reference current value and the current change information;

[0044] Obtain a reference current value and calculate a current deviation rate, where the reference current value is determined based on the ambient temperature and the compressor speed;

[0045] If the current deviation rate is greater than the current deviation threshold, output a defrost instruction, where the defrost instruction is used to trigger a defrost condition.

[0046] As can be seen from the above technical solutions, the present application provides a method for judging evaporator defrosting and a variable-frequency refrigerator. The method includes: detecting a variable-frequency drive to output current change information, where the current change information is information obtained through changes in the compressor load; then obtaining a reference current value and calculating a current deviation rate, where the reference current value is determined based on the ambient temperature and the compressor speed, and the current deviation rate is calculated through the reference current value and the current change information; if the current deviation rate is greater than the current deviation threshold, output a defrost instruction, where the defrost instruction is used to trigger a defrost condition. The method can collect and output the current in real time through the variable-frequency drive, and the change in the output current can detect the frosting condition of the evaporator in real time, without being affected by conditions such as the humidity of the items stored by the user, the quantity of the items, and the number of door openings, and can reflect the frosting condition of the evaporator, so as to solve the problem of inaccurate defrosting judgment by the defrosting judgment mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a schematic flowchart of the method for judging evaporator defrosting provided by the embodiment of the present application;

[0049] Figure 2 It is a schematic diagram of the relationship curve between the current change information, the compressor speed, and the ambient temperature provided by the embodiment of the present application;

[0050] Figure 3 It is a schematic flowchart of the generation of the first alarm instruction provided by the embodiment of the present application;

[0051] Figure 4 It is a schematic flowchart of the generation of the second alarm instruction provided by the embodiment of the present application;

[0052] Figure 5 It is a schematic diagram of the operation scenario between the refrigeration device and the mobile terminal provided by some embodiments of the present application;

[0053] Figure 6 For some embodiments of the present application Figure 5 hardware configuration block diagram of the refrigerator in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] The following embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following embodiments do not represent all implementations consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application as detailed in the claims.

[0055] In a home scenario, refrigerators need to adapt to changes in ambient temperature in different seasons, humidity fluctuations caused by frequent opening and closing of doors, and the diversity of items stored by users.

[0056] For example, in the high temperature environment in summer, the temperature difference between the inside and outside of the refrigerator increases, and the high-frequency operation of the compressor makes it easier for frost to form on the evaporator surface; in the low temperature environment in winter, users may reduce the frequency of opening the door to slow down the frost rate, but the low temperature environment itself may aggravate the problem of frost hardening.

[0057] In commercial scenarios, refrigerators need to operate at high load for a long time, and frequent storage and retrieval of items inside causes drastic fluctuations in humidity, and the frost rate is significantly higher than in home scenarios.

[0058] In addition, special environments, such as high temperature and high humidity areas, and inland areas with large temperature differences between day and night, place higher requirements on the real-time performance and environmental adaptability of the defrost judgment mechanism.

[0059] The defrost judgment technology includes a timed defrost method based on preset rules and a frost layer thickness detection method based on sensors.

[0060] Among them, the timed defrosting method based on preset rules sets a fixed defrosting cycle (such as once every 8 hours) or a threshold of the cumulative running time of the compressor (such as defrosting is triggered after the compressor has run for 4 hours) through experimental data or experience. For example, the compressor running time and ambient temperature compensation rule is adopted, and defrosting is started when the cumulative running time of the compressor reaches the set value and the ambient temperature is lower than 25°C.

[0061] The control unit has a built-in timing module to accumulate the compressor running time or count the defrost interval period, and trigger the defrost program when the threshold is reached. Some solutions introduce a temperature compensation coefficient to fine-tune the defrost frequency according to the ambient temperature.

[0062] The sensor-based frost thickness detection method uses the infrared light or laser reflection principle to detect the frost thickness. The sensor transmits a light signal to the evaporator surface and determines the degree of frost accumulation by receiving the change in the intensity of the reflected light. For example, the thickening of the frost layer causes the reflected light to attenuate, and defrosting is triggered when the light intensity is lower than the preset threshold.

[0063] The capacitive sensor indirectly calculates the frost layer thickness by detecting the change in the capacitance value on the surface of the evaporator. As a dielectric substance, the increase in the thickness of the frost layer will cause the capacitance value between the sensor plates to rise. When the change in capacitance exceeds the set range, defrosting is initiated. The sensor module is integrated near the evaporator, collects data in real time, and transmits it to the control unit. After eliminating noise interference by combining with a filtering algorithm, a defrosting instruction is generated.

[0064] The development cycle of the preset rule defrosting method is long. A large number of experiments need to be carried out for different refrigerator models to determine the defrosting cycle or time threshold, resulting in low efficiency in the development of new products. For example, it takes months to test the frosting rate at various ambient temperatures such as 10°C, 25°C, and 40°C.

[0065] The fixed threshold cannot adapt to the dynamically changing frosting rate in actual use. For example, when users store a large number of high-humidity food ingredients, the frosting rate may increase, but the preset rule still defrosts according to the original cycle, resulting in delayed defrosting; on the contrary, if users reduce the frequency of opening the door, defrosting may be triggered prematurely, causing energy waste. Frequent defrosting causes temperature fluctuations inside the refrigerator, affecting food preservation; too long a defrosting interval increases the load on the compressor and raises energy consumption.

[0066] The hardware cost of the sensor detection scheme is high. Optical or capacitive sensors need to be purchased separately and integrated into the refrigerator structure, increasing the overall cost of the machine. The environmental tolerance is insufficient. The sensors are long-term exposed to low-temperature and high-humidity environments, and are prone to performance degradation or failure. For example, the mirror surface of the optical sensor is fogged, resulting in distorted optical signals, and the oxidation of the capacitor sensor plates causes detection drift. After the sensor fails, it needs to be disassembled by professional personnel to replace the evaporator components, significantly increasing the maintenance cost and downtime.

[0067] To solve the above problems, in some embodiments, the defrosting threshold is dynamically adjusted by parameters such as ambient temperature and the number of door openings. For example, when the ambient temperature rises or the door opening frequency increases, the defrosting cycle is automatically shortened.

[0068] However, the frosting rate is jointly affected by multiple factors (humidity, load, fan speed, etc.). It is difficult to accurately match the actual needs with a single parameter adjustment. The adaptive algorithm requires a large amount of historical data for training, and its generalization ability is insufficient in new models or special scenarios.

[0069] In some other embodiments, a dual-sensor redundant layout is adopted (such as cross-verification of optical and capacitive sensors), and a regular self-calibration program is set (such as triggering calibration at a preset time every day).

[0070] However, the dual-sensor scheme exacerbates the hardware cost pressure and offsets the benefits brought by the improved reliability. Calibration needs to be carried out in a frost-free state. If users frequently use the refrigerator, resulting in insufficient calibration windows, it may cause mis-calibration.

[0071] It is also possible to use a hybrid defrost judgment mechanism, that is, combining preset rules with sensor detection, mainly relying on sensor data and supplemented by rule adjustment. For example, sensor-triggered defrost is preferred, and when the sensor fails, it switches to the preset rule.

[0072] However, when the sensor and the rule judgment results are inconsistent (such as false alarms from the sensor but the rule does not reach the threshold), a complex mechanism is required, increasing the system complexity.

[0073] In summary, although the preset rule scheme for defrost judgment of variable-frequency air-cooled refrigerators has a low cost, its intelligent level is insufficient. The sensor scheme has high accuracy, but its hardware cost and environmental tolerance restrict its popularization; the hybrid scheme introduces new complexity and compatibility problems. Therefore, the accuracy and adaptability of the defrost mechanism are relatively low.

[0074] To solve the problem of relatively low accuracy and adaptability of the defrost mechanism, as Figure 1 shown, some embodiments of the present application provide an evaporator defrost judgment method, including:

[0075] S100: Detect the variable-frequency drive to output current change information.

[0076] The variable-frequency drive is a variable-frequency controller using Field-Oriented Control (FOC) technology. It realizes stepless adjustment of the compressor speed by adjusting the motor power supply frequency and voltage. The frosting state is indirectly detected through the variable-frequency drive current, without the need to add a frost layer thickness sensor or an optical detection module, reducing the hardware cost.

[0077] The current change information is the information obtained through the change of the compressor load. In some embodiments, based on field-oriented control, the three-phase current signals of the motor are collected, and the three-phase current signals are transformed to be converted into a direct-axis current component and a quadrature-axis current component; based on the vector control algorithm, the motor output torque is calculated through the direct-axis current component and the quadrature-axis current component; according to the torque, the change of the compressor load is identified to output the current change information.

[0078] The three-phase current signals (IA, IB, IC) of the motor are collected in real time through a current sensor, and are converted into current components (Id, Iq) in the α-β coordinate system through Clark (Clarke Transform), and then converted into the direct-axis current Id and the quadrature-axis current Iq in the synchronous rotating coordinate system through Park Transform (Park Transform). Among them, Id is used to control the motor excitation, and Iq directly determines the output torque. The changes of the two reflect the compressor load state.

[0079] Clark transformation and Park transformation are the core algorithm steps of field-oriented control (FOC), which are used to convert the three-phase stationary coordinate system current into the direct-axis and quadrature-axis current components in the rotating coordinate system, so as to realize the decoupling control of torque and excitation.

[0080] By analyzing the direct-axis and quadrature-axis current components through FOC technology, the compressor load status can be directly correlated. For example, a slight change in the Iq component (such as 0.5 A) can identify the initial frosting state, improving the detection sensitivity. FOC technology realizes the real-time decoupling and control of current components. For example, when the compressor speed changes suddenly, the Id and Iq components can be adjusted within milliseconds to ensure the real-time nature of load identification and defrosting determination.

[0081] The current change is the change in the output current of the variable-frequency drive caused by the change in the compressor load. Specifically, the frosting condition of the evaporator will affect the compressor load. When the evaporator frosts, its heat exchange efficiency will decrease. To maintain the normal operation of the refrigeration system, the compressor needs to overcome greater resistance to compress the refrigerant, resulting in an increase in the compressor load.

[0082] The increase in the compressor load will be reflected in the output current of the variable-frequency drive. Since the compressor is controlled by the variable-frequency drive, when the load increases, the motor needs to output greater power. According to the power formula, the current will increase accordingly. Conversely, when the frosting condition of the evaporator improves and the heat exchange efficiency increases, the compressor load decreases, and the output current of the variable-frequency drive will also decrease accordingly.

[0083] The current change is a dynamic process that changes in real time with the change in the frosting degree of the evaporator and the operating conditions of the refrigeration system. By detecting this current change in real time, the load condition of the compressor can be indirectly understood, and then the frosting state of the evaporator can be judged.

[0084] S200: Obtain the reference current value and calculate the current deviation rate.

[0085] The reference current value is determined based on the ambient temperature and the compressor speed. The reference current value is the standard output current value of the variable-frequency drive at different ambient temperatures and speeds obtained through pre-calibration in the state where the evaporator is not frosted. The reference current value is a reference value representing the current level of the refrigeration system under normal and frost-free conditions.

[0086] The output current of the variable-frequency drive detected in real time will deviate from the reference current value due to the change in the compressor load caused by the frosting of the evaporator. By calculating the deviation rate between the real-time current and the reference current value, this deviation degree can be quantified.

[0087] For example, at an ambient temperature of 20°C and a rotational speed of 2500 rpm, the reference current value is 4.2 A. This data is obtained by conducting multiple sets of operating condition tests on the refrigerator under laboratory conditions, forming a three-dimensional database of temperature-rotational speed-current, which is stored in the non-volatile memory of the variable frequency drive MCU.

[0088] In this embodiment, the variable frequency drive output current within the full rotational speed range of the compressor, i.e., the reference current, when the refrigerator is at ambient temperatures of 10°C, 20°C, 30°C, and 40°C and the refrigerator evaporator is not frosted, is determined through experimental calibration and is respectively denoted as where z represents the rotational speed of the compressor, and these currents are stored in the variable frequency drive MCU. For the sake of convenient expression, it is denoted as where z represents the rotational speed of the compressor, and x represents the ambient temperatures of 10°C, 20°C, 30°C, and 40°C.

[0089] In some embodiments, to obtain the reference current value, the ambient temperature is acquired and divided into preset temperature intervals; based on the preset temperature intervals, the reference current value is calibrated, and the reference current value is the reference current output by the variable frequency drive corresponding to the rotational speed of the compressor in the non-frosted state of the evaporator.

[0090] When the refrigerator is powered on for the first time, the controller acquires the current ambient temperature through the ambient temperature sensor and classifies it into the corresponding preset temperature interval. Then, it reads the reference current mapping table of this temperature interval and loads the data into the buffer area of the MCU. At the same time, the FOC control is initialized, and the sampling frequency of the current sensor and the Clark-Park transformation parameters are configured.

[0091] Introduce the correction of the reference current value with humidity data to cover the scenario of accelerated frosting in a high-humidity environment. For example, during the plum rain season or when storing a large amount of fruits and vegetables, the reference current value is lowered through the humidity compensation coefficient to make the deviation rate calculation more sensitive. In some embodiments,

[0092] Acquire humidity data and set humidity intervals;

[0093] Match the humidity data to the humidity intervals and call the humidity compensation coefficient according to the humidity intervals;

[0094] Generate the corrected reference current value, where the corrected reference current value is the product of the humidity compensation coefficient and the reference current value.

[0095] The humidity data is collected through a humidity sensor, and the humidity sensor is integrated near the evaporator or in the refrigerating chamber air duct for real-time monitoring of the relative humidity of the air inside the box.

[0096] For example, a capacitive humidity sensor outputs a humidity signal by detecting the change in the dielectric constant between the electrodes. The signal is transmitted to the control unit after analog-to-digital conversion. The humidity data reflects the degree of moisture volatilization of the items stored by the user and the amount of external humid air introduced by the frequency of opening the door, which directly affects the frosting rate of the evaporator.

[0097] The preset humidity range is the basis for classifying the humidity inside the box. For example, it is divided into a low humidity range (relative humidity ≤ 50%), a medium humidity range (50% - 70%), and a high humidity range (> 70%). The classification rules are determined based on historical frosting experiment data. For example, in a high humidity environment, the frosting rate under the same compressor load is 30% faster than in a low humidity environment. The current humidity is classified into the corresponding range. For example, when the detected humidity is 65%, it is classified into the medium humidity range.

[0098] The humidity compensation coefficient is the current correction factor corresponding to each humidity range, which is used to adjust the reference current value to match the actual frosting rate. For example, the compensation coefficient for the low humidity range is 1.05 (slowing down the reduction rate of the reference current), and for the high humidity range is 0.92 (accelerating the reduction of the reference current). The compensation coefficient is calibrated under the condition that the evaporator is not frosted: at a constant ambient temperature and compressor speed, measure the normal load current corresponding to different humidities, and calculate the compensation coefficient = calibrated current / reference current.

[0099] Multiply the reference current value by the humidity compensation coefficient to generate a corrected reference current suitable for the current humidity. For example, the original reference current (at an ambient temperature of 20°C and 3000 RPM) is 12.5 A. When the detected high humidity (75%) is detected, the compensation coefficient 0.92 is called, and the corrected reference current = 12.5 × 0.92 = 11.5 A. The corrected reference current is closer to the real load state, avoiding misjudgment of the deviation rate caused by humidity fluctuations.

[0100] Exemplarily, the humidity sensor monitors the humidity inside the box in real time as 68%. According to the preset rules, it is classified into the medium humidity range (50% - 70%). At the same time, the temperature sensor detects the ambient temperature as 22°C, and the compressor speed is 2800 RPM.

[0101] The control unit calls the reference current value of 13.0 A corresponding to an ambient temperature of 22°C and 2800 RPM, and calls the compensation coefficient 0.98 according to the medium humidity range. The corrected reference current value is 12.74 A.

[0102] By dynamically correcting the reference current value through the humidity compensation coefficient, the problem of defrosting lag caused by accelerated frosting in a high humidity environment can be solved. For example, when storing fresh fruits and vegetables, the humidity compensation reduces the reference current value, so that the deviation rate corresponding to the same frosting degree exceeds the threshold faster, avoiding excessive frost layer thickness from affecting the refrigeration efficiency.

[0103] The corrected reference current value is closer to the actual load state, reducing false triggering caused by sudden humidity changes (such as moisture introduced by frequent door opening). For example, when the humidity increases briefly, the compensation coefficient only slightly adjusts the reference current value to avoid misjudgment caused by violent fluctuations in the deviation rate.

[0104] The output current of the variable-frequency drive detected in real time will deviate from the reference current value as the compressor load changes due to frosting of the evaporator. By calculating the deviation rate between the real-time current and the reference current value, the degree of this deviation can be quantified, that is, the current deviation rate.

[0105] The current deviation rate is calculated based on the reference current value and the current change information. In some embodiments, based on the reference current value, the preset temperature range, and the compressor speed, a mapping relationship is generated. The mapping relationship is the associated data of the preset temperature range, the compressor speed, and the reference current value, and is stored in the control unit in the form of a look-up table, as Figure 2 shown.

[0106] Then, the ambient temperature and the compressor speed are obtained. The ambient temperature is the current ambient temperature, and the compressor speed is the current compressor speed; the preset temperature range is determined based on the ambient temperature; and the reference current value is matched according to the mapping relationship based on the preset temperature range and the compressor speed.

[0107] As Figure 2 shown, the preset temperature range includes a first temperature range, a second temperature range, a third temperature range, and a fourth temperature range; the first temperature range is x≤15°C, the second temperature range is 15 - 25°C, the third temperature range is 25 - 35°C, and the first temperature range is 35 - 43°C. For example, when the detected ambient temperature is 22°C, it is classified into the third temperature range.

[0108] By calibrating the reference current value in different temperature ranges, the problem that a single reference value cannot adapt to temperature changes is solved. For example, in a high-temperature environment, the compressor load is low, and the reference current value is correspondingly reduced; while in a low-temperature environment, the reference current value increases with the increase of the load, and the dynamic matching mechanism ensures the judgment accuracy under different working conditions.

[0109] When the ambient temperature (x≤15°C), according to the real-time speed, the reference current takes the corresponding value; when the ambient temperature (15°C < x≤25°C), according to the real-time speed, the reference current takes the corresponding value; when the ambient temperature (25°C < x≤35°C), according to the real-time speed, the reference current takes the corresponding value; when the ambient temperature (35°C < x≤43°C), according to the real-time speed, the reference current takes the corresponding value.

[0110] The current deviation rate is the relative difference between the real-time detected current and the reference current value. In some embodiments, the output current of the variable-frequency drive is obtained; based on the output current of the variable-frequency drive and the reference current value, the difference is calculated; the current deviation rate is calculated, and the current deviation rate is the ratio of the difference to the reference current value.

[0111] The current deviation rate is calculated by the following formula:

[0112]

[0113] where, I 实时 is the real-time detected current, is the reference current.

[0114] The current deviation rate reflects the degree of load change caused by the frosting of the evaporator. For example, ΔI = 12%, indicating that the current is 12% higher than the reference value, indirectly indicating that the increase in thermal resistance leads to an increase in the compressor load.

[0115] When the deviation rate is small, that is, less than the current deviation threshold, it means that the current is close to the reference current value, and the evaporator may be in a normal working state with less frosting; when the deviation rate is greater than the current deviation threshold and lasts for a preset time, it means that the deviation between the current and the reference current value is large, indicating a significant increase in the compressor load, and then inferring that the frosting thickness of the evaporator reaches the condition for defrosting.

[0116] S300: If the current deviation rate is greater than the current deviation threshold, output a defrosting instruction.

[0117] The defrosting instruction is used to trigger the defrosting condition. The defrosting instruction is a control signal sent by the controller to trigger the defrosting heater to work. For example, the trigger condition of the defrosting instruction is that the current deviation rate exceeds the current deviation threshold (such as 10%), and at this time, it is determined that the frosting thickness of the evaporator reaches the defrosting condition, and the defrosting program is started.

[0118] Exemplarily, when the refrigerator is powered on for the first time, the current ambient temperature is obtained through the ambient temperature sensor and classified into the corresponding preset interval. The mapping table of this temperature interval is read, and the data is loaded into the buffer of the MCU. At the same time, the FOC control is initialized, and the sampling frequency of the current sensor and the Clark-Park transformation parameters are configured.

[0119] After the compressor starts, it enters the closed-loop control state. The current compressor speed and the real-time ambient temperature are collected every 5 minutes. According to the current speed and the ambient temperature interval, the reference current reference is obtained by querying the mapping table. The real-time current is obtained through the FOC control, and this value is calculated by the Clark-Park transformation of the three-phase current of the motor.

[0120] Then calculate the current deviation rate ΔI. When ΔI exceeds the current deviation threshold, it is determined that the evaporator frosting has reached the defrosting condition, and a defrosting instruction is output. At this time, the compressor stops running, the defrosting heater starts, and at the same time, the temperature change of the evaporator is monitored. When the evaporator temperature reaches the preset termination temperature, the defrosting program terminates and the refrigeration cycle is restored.

[0121] To avoid energy waste caused by premature defrosting, as Figure 3 shown, in some embodiments, the current deviation threshold includes a first deviation rate threshold.

[0122] If the current deviation rate is greater than the first deviation rate threshold, obtain a first preset duration, where the first preset duration is the duration during which the current deviation rate is greater than the first deviation rate threshold;

[0123] If the first preset duration is greater than the duration threshold, generate a first alarm signal, where the first alarm signal indicates that the frosting thickness of the evaporator is the first thickness.

[0124] Exemplarily, the real-time collected current is 10.2A, the difference between the real-time current and the reference current value is calculated as 1.6A, the deviation rate is 6.375%, and the deviation rate of 6.375% exceeds the first deviation rate threshold (5%). Start the continuous duration verification. If the first preset duration is greater than the duration threshold.

[0125] The first alarm signal is a mild frosting alarm, the first deviation rate threshold is 5%, and the duration threshold is 3 minutes. Exemplarily, when the current deviation rate reaches 6.375%, start the timer. If the current deviation rate does not drop below 5% within 3 minutes, the first alarm signal is triggered.

[0126] In some embodiments, the current deviation threshold further includes a second deviation rate threshold.

[0127] As Figure 4 shown, if the current deviation rate is greater than the second deviation rate threshold and the first preset duration is greater than the duration threshold, generate a second alarm signal and a defrosting instruction. The second alarm signal indicates that the frosting thickness of the evaporator is the second thickness, and the second thickness is greater than the first thickness.

[0128] If the current deviation rate further rises to 12%, that is, exceeds the second deviation rate threshold of 10%, start the preset duration timer. For example, during a 3-minute continuous period, if the deviation rate remains between 11% and 13%, after the timing ends, trigger the defrosting instruction, and the heater starts and defrosting begins.

[0129] Distinguish between mild and severe frosting states through two - level deviation rate thresholds and duration verification. For example, when the deviation rate briefly exceeds 5% but quickly recovers, only record the anomaly without triggering an action; when the deviation rate continuously exceeds 10%, start defrosting after confirming the stable accumulation of the frost layer to avoid frequent ineffective defrosting.

[0130] After the heater works, the temperature sensor monitors the evaporator temperature in real - time. When the temperature rises to 10°C, after the heater is turned off, reset the compressor operation time counter.

[0131] In some embodiments, in response to the defrosting instruction, control the defrosting heater to work and obtain the evaporator temperature; when the evaporator temperature is greater than or equal to the preset defrost termination temperature, record the compressor operation time, and obtain the reference current value based on the compressor operation time.

[0132] For example, the defrosting process takes 20 minutes. After completion, the compressor restarts, the cumulative operation time returns to zero, and it re - enters the detection cycle, continuously monitoring the change of the ambient temperature. For example, when the ambient temperature drops to 12°C, automatically switch to the 10°C ambient temperature curve, match the new reference current value, and ensure that the judgment logic is dynamically optimized with the environment.

[0133] After defrosting, the compressor operation time returns to zero, which can make the next detection based on the latest data and avoid interference from historical frosting cycles. For example, the clean evaporator state after the previous defrost is completely isolated from the detection logic of the new cycle, improving the judgment accuracy.

[0134] The judgment method provided in this embodiment accurately realizes the detection of evaporator frosting without increasing costs through the existing field - oriented variable - frequency control technology of variable - frequency refrigerators. When the evaporator frosts, the heat exchange efficiency decreases, the compressor load increases, and finally the output current of the variable - frequency drive becomes larger. It can truly reflect the frosting situation of the evaporator and has the characteristics of timeliness and accuracy.

[0135] Based on the above - mentioned evaporator defrosting judgment method, some embodiments of the present application also provide a variable - frequency refrigerator, including:

[0136] A controller, configured to:

[0137] Detect the variable - frequency drive to output current changes, which are caused by changes in the compressor load;

[0138] Obtain a reference current value and calculate the current deviation rate, where the reference current value is determined based on the ambient temperature and the compressor speed;

[0139] If the current deviation rate is greater than the current deviation threshold, output a defrosting instruction, where the defrosting instruction is used to trigger the defrosting condition.

[0140] It can be understood that the variable-frequency refrigerator provided in this embodiment is provided with a refrigerating chamber and a freezing chamber.

[0141] Among them, the main function of the refrigerating chamber is to keep fresh. It is located in the upper half of the refrigerator, and the designed temperature is higher than 0°C and between 2°C and 8°C. This temperature range is sufficient to slow down the growth rate of bacteria in food, thereby extending the shelf life of food, while maintaining the freshness and taste of food. In the refrigerating chamber, various perishable foods such as vegetables, fruits, dairy products, cooked meat, and leftovers can be stored.

[0142] Among them, the main function of the freezing chamber is to freeze and store food for a long time. It is usually located in the lower half of the refrigerator, and the temperature is much lower than 0°C, generally below -18°C. At this extremely low temperature, the moisture in the food will quickly freeze, thereby effectively preventing the growth of bacteria and enabling the food to be stored for a long time without spoiling. In the freezing chamber, meat, fish, ice cream, frozen foods, etc. can be stored for a long time.

[0143] Figure 5 It is a schematic diagram of the operation scenario between the refrigeration device and the mobile terminal provided in some embodiments of the present application. As Figure 5 shown, the user can control the refrigerator by touching and operating the mobile terminal 300. Among them, the mobile terminal 300 is used to receive the operation instructions input by the user and convert the operation instructions into control instructions that the refrigerator can recognize and respond to. For example, the mobile terminal 300 can be a device such as a mobile phone, a tablet computer, or a computer.

[0144] The mobile terminal 300 can be used as a control device for performing human-computer interaction between the user and the refrigerator. The mobile terminal 300 can also be used as a communication device for establishing a communication connection with the refrigerator and performing data interaction. In some embodiments, the mobile terminal 300 can be installed with software applications with the refrigerator, and achieve connection communication through network communication protocols to achieve the purpose of one-to-one control operation and data communication.

[0145] In some embodiments, the mobile terminal 300 or other electronic devices can also simulate the functions of the refrigerator by running an application program for controlling the refrigerator.

[0146] In some embodiments, the mobile terminal 300 can communicate with the refrigerator for data communication through various communication methods. The mobile terminal 300 is allowed to communicate with the refrigerator through a local area network (LAN), a wireless local area network (WLAN), and other networks.

[0147] Figure 6 For some embodiments of the present application Figure 5 is the hardware configuration block diagram of the refrigerator in

[0148] In one embodiment, the refrigerator may include at least one of a communication device 210, a sensor 220, a refrigeration component 230, a controller 250, a display 240, a memory, a power supply, and a user input interface 260.

[0149] In some embodiments, the sensor 220 is configured to collect signals of the internal and external environments of the refrigerator. For example, the sensor 220 includes a temperature sensor for collecting the temperature inside the refrigerator or the external environment temperature; alternatively, the sensor 220 includes a humidity sensor that can be used to collect the humidity inside the refrigerator.

[0150] In some embodiments, the display 240 includes a display function component for presenting a picture and a driving component for driving image display. The display 240 is configured to receive an image signal output from the controller 250 for display. For example, the display 240 can be used to display components such as image content, menu manipulation interfaces, and user manipulation UI interfaces. The specific content to be displayed may include refrigerator parameters, environmental parameters, item information, refrigeration plans, and so on.

[0151] In some embodiments, the communication device 210 is a component for communicating with external devices according to various communication protocol types. The refrigerator may be provided with multiple communication devices 210 according to different supported communication methods. For example, when the refrigerator supports wireless network communication, the refrigerator may be provided with a communication device 210 including Wi-Fi function. When the refrigerator supports Bluetooth connection communication, the display device 200 needs to be provided with a communication device 210 including Bluetooth function.

[0152] The communication device 210 can communicate and connect the refrigerator with external devices in a wireless or wired connection manner. Among them, the wired connection can connect the refrigerator with external devices through components such as data lines and interfaces. The wireless connection can connect the refrigerator with external devices through wireless signals or wireless networks. The refrigerator can directly establish a connection relationship with external devices or indirectly establish a connection relationship through gateways, routers, connection devices, etc.

[0153] In some embodiments, the controller 250 may include at least one of a central processing unit and a power processor, and first to n interfaces for input / output. The controller 250 controls the operation of the refrigerator and responds to user operations through various software control programs stored in the memory. The controller 250 controls the overall operation and refrigeration work of the refrigerator.

[0154] In some embodiments, if a user inputs a user command on the graphical user interface (GUI) displayed on the display 240, the user input interface 260 receives the user input command through the graphical user interface (GUI).

[0155] In some embodiments, the user input interface 260 can be used to receive instructions from user input, such as importing refrigeration parameters or rules desired by the user.

[0156] In some embodiments, the refrigeration component 230 may include at least one of a compressor, a condenser, a capillary tube, and an evaporator.

[0157] Exemplarily, the main function of the compressor is to increase the pressure and temperature of the refrigerant vapor, thereby establishing a necessary pressure difference in the refrigeration system and prompting the refrigerant to circulate in the refrigeration system.

[0158] Exemplarily, the main function of the condenser is to release heat from the high-temperature and high-pressure refrigerant vapor and condense it into a liquid. During the above process, the refrigerant vapor dissipates a large amount of heat to the outside of the refrigerator.

[0159] Exemplarily, the main function of the capillary tube is to restrict the liquid flow rate of the refrigerant and control the pressure difference between the condenser and the evaporator through its flow resistance.

[0160] Exemplarily, the main function of the evaporator is to rapidly boil and evaporate the liquid refrigerant under low-temperature and low-pressure conditions, thereby absorbing the heat inside the refrigerator and reducing the temperature inside the refrigerator.

[0161] Exemplarily, when the refrigerator is running, the controller 250 adjusts the operating power of the compressor and the evaporator in real time according to the temperature data collected by the sensor 220 and the requirements of the factory settings, so that the temperature inside the refrigerator reaches the set temperature.

[0162] For the similar parts between the embodiments provided in this application, reference can be made to each other. The specific embodiments provided above are only several examples under the general concept of this application and do not constitute a limitation on the protection scope of this application. For those skilled in the art, any other embodiments extended based on the solution of this application without creative efforts belong to the protection scope of this application.

Claims

1. A method for judging defrosting of an evaporator, characterized in that: include: Detecting the variable frequency drive to output current change information, wherein the current change information is information obtained through changes in the compressor load; Obtaining a reference current value and calculating a current deviation rate, wherein the reference current value is determined based on an ambient temperature and a compressor speed, and the current deviation rate is calculated based on the reference current value and current change information; If the current deviation rate is greater than the current deviation threshold, a defrost instruction is output, where the defrost instruction is used to trigger a defrost condition.

2. The method for determining defrosting of an evaporator according to claim 1, characterized in that: The obtaining of the reference current value comprises: Acquiring ambient temperature, and dividing the ambient temperature into preset temperature intervals; Based on the preset temperature range, a reference current value is calibrated, where the reference current value is a reference current output by the variable frequency drive corresponding to the speed of the compressor when the evaporator is not frosted.

3. The method for determining defrosting of an evaporator according to claim 2, characterized in that: The calculating of the current deviation rate comprises: generating a mapping relationship based on the reference current value, the preset temperature range and the compressor speed; Acquire the ambient temperature and the compressor speed, wherein the ambient temperature is the current ambient temperature and the compressor speed is the current compressor speed; determining a preset temperature range based on the ambient temperature; Based on the preset temperature range and the compressor speed, the reference current is matched according to the mapping relationship.

4. The method for determining defrosting of an evaporator according to claim 3, characterized in that: The calculating of the current deviation rate comprises: Get the variable frequency drive output current; Calculating a difference based on the variable frequency drive output current and the reference current value; The current deviation rate is calculated, where the current deviation rate is a ratio of the difference value to the reference current value.

5. The method for determining defrosting of an evaporator according to claim 1, characterized in that: The current deviation threshold comprises a first deviation rate threshold; If the current deviation rate is greater than the current deviation threshold, outputting a defrost instruction comprises: If the current deviation rate is greater than a first deviation rate threshold, obtaining a first preset time length, where the first preset time length is a time length during which the current deviation rate is greater than the first deviation rate threshold; If the first preset time length is greater than the time length threshold, a first alarm signal is generated, wherein the first alarm signal indicates that the frost thickness of the evaporator is a first thickness.

6. The method for determining defrosting of an evaporator according to claim 5, characterized in that: The current deviation threshold comprises a second deviation rate threshold, and the second deviation rate threshold is greater than the first deviation rate threshold; If the current deviation rate is greater than the current deviation threshold, outputting a defrost instruction comprises: If the current deviation rate is greater than a second deviation rate threshold and the first preset duration is greater than the duration threshold, a second alarm signal and a defrost instruction are generated, wherein the second alarm signal indicates that the frost thickness of the evaporator is a second thickness, and the second thickness is greater than the first thickness.

7. The method for determining defrosting of an evaporator according to claim 6, characterized in that: The method further comprises: In response to the defrost instruction, the defrost heater is controlled to operate, and the evaporator temperature is obtained; When the evaporator temperature is greater than or equal to a preset defrost termination temperature, the compressor operation time is recorded, and a reference current value is obtained based on the compressor operation time.

8. The method for determining defrosting of an evaporator according to claim 1, characterized in that: The detection variable frequency drive is used to output current change information, including: Based on field-oriented control, the three-phase current signal of the motor is collected; Transforming the three-phase current signal to convert it into a direct-axis current component and a quadrature-axis current component; Based on a vector control algorithm, the motor output torque is calculated through the direct-axis current component and the quadrature-axis current component; Based on the torque, a change in the compressor load is identified to output current change information.

9. The method for determining defrosting of an evaporator according to claim 1, characterized in that: The obtaining of the reference current value further includes: Get humidity data and set the humidity range; Matching the humidity data to the humidity interval, and calling a humidity compensation coefficient according to the humidity interval; A corrected reference current value is generated, wherein the corrected reference current value is the product of the humidity compensation coefficient and the reference current value.

10. A variable frequency refrigerator, characterized in that: The method for determining defrosting of an evaporator according to any one of claims 1 to 9 comprises: The controller is configured as: Detecting a variable frequency drive to output a current change, the current change being caused by a change in the compressor load, the current deviation rate being calculated by a reference current value and current change information; Obtaining a reference current value and calculating a current deviation rate, wherein the reference current value is determined based on an ambient temperature and a compressor speed; If the current deviation rate is greater than the current deviation threshold, a defrost instruction is output, where the defrost instruction is used to trigger a defrost condition.

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