A method, system and device for operating mode sensing switching control of a refrigeration appliance

Abstract

The application discloses a running mode sensing switching control method, system and device of a refrigeration equipment, and belongs to the technical field of intelligent control and energy saving and emission reduction of the refrigeration equipment. The method comprises the following steps: collecting multi-dimensional state flow data, calculating a sliding time window feature, identifying a running mode, calling a cooperative control law, and modifying a safety constraint; switching is performed between running modes such as frequent door opening disturbance, rapid temperature drawing, stable energy saving maintenance, self-adaptive intelligent defrosting, and heat control after defrosting according to a preset priority; and before outputting a control vector, a variable frequency compressor frequency modulation slope constraint, a variable frequency compressor shortest start-stop time constraint, and a heat exchange abnormal load reduction protection constraint are superposed, so that energy saving operation is considered while ensuring temperature control precision and recovery speed, defrosting time precision and temperature stability after defrosting are realized, current impact, mechanical impact and system oscillation are reduced, and long-term safe and reliable operation of the equipment is ensured.

Description

Technical Field

[0001] This invention belongs to the field of intelligent control and energy-saving emission reduction technology for refrigeration equipment, specifically relating to a method, system, and device for sensing and switching operating modes of refrigeration equipment. The refrigeration equipment includes, but is not limited to, refrigerators, freezers, kitchen refrigerators and freezers, convenience store display cases, beverage display cases, and other commercial refrigeration terminals equipped with variable frequency compressors and evaporator fans. Background Technology

[0002] Refrigeration equipment typically operates under complex conditions, including frequent door openings, large load fluctuations, significant changes in ambient humidity, and substantial differences in the heat capacity of stored items. This places high demands on temperature recovery speed, energy consumption levels, defrosting effectiveness, and internal temperature stability.

[0003] Existing refrigeration control methods mostly employ temperature threshold control, conventional proportional-integral-derivative (PID) regulation, fixed-time defrosting, and rule-based control based on single sensor states. While these methods are structurally simple, they are prone to problems such as response lag, control action conflicts, ineffective defrosting, temperature rebound, and compressor frequency fluctuations under conditions such as frequent door openings, concentrated restocking, high-humidity frosting, and defrosting recovery.

[0004] First, during peak usage, concentrated restocking, or prolonged retrieval of goods, when hot and humid air rapidly enters the cabinet, the internal temperature rises abruptly. Since the cabinet, goods, and evaporator all have thermal inertia, relying solely on a single temperature deviation for feedback control will lead to a lag in control commands, manifested as slow temperature recovery, large fluctuations in compressor frequency, and increased additional energy consumption.

[0005] Secondly, the evaporator surface temperature is low, making frost formation inevitable during operation. The frost layer increases heat exchange resistance and weakens the evaporator's heat exchange capacity. Frosting is exacerbated in high humidity environments or after frequent door opening. Fixed-time defrosting is difficult to match the actual frost condition, easily leading to premature defrosting when the frost layer is thin, wasting energy, or delayed defrosting when there is severe frost, resulting in decreased cooling efficiency and increased temperature fluctuations in the unit.

[0006] Third, there is a clear temporal coupling between the target frequency of the variable frequency compressor, the target speed of the evaporator fan, and the on / off state of the defrosting heating wire. If the fan is resumed immediately after defrosting, residual heat and moisture near the evaporator may be carried into the chamber, causing a temperature rebound after defrosting.

[0007] Fourth, if the frequency of the variable frequency compressor changes too rapidly or starts and stops frequently, it may cause current surges, system oscillations, or mechanical shocks. Therefore, there is an urgent need for a switching control method that can identify operating modes, invoke control strategies according to the modes, and superimpose safety constraints to meet the temperature control accuracy and energy-saving requirements of refrigeration equipment under complex operating conditions. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a method for sensing and switching control of operating modes of refrigeration equipment, which addresses issues such as control response lag, inaccurate defrosting timing, uncoordinated operation of compressor and fan, and unstable mode switching during frequent door opening, centralized replenishment, evaporator frosting, defrosting withdrawal, and recovery after defrosting.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] A method for sensing and switching control of operating modes of a refrigeration device includes the following steps:

[0011] Step A: Multidimensional state flow data acquisition;

[0012] Multidimensional state flow data of the refrigeration equipment is collected according to a fixed sampling period. The multidimensional state flow data includes at least the internal temperature of the chamber, the evaporator tube wall temperature, the ambient temperature, the door opening and closing status, and the operating current of the variable frequency compressor.

[0013] Step B: Calculation of sliding time window features;

[0014] A sliding time window is constructed based on the multidimensional state flow data, and the sliding time window features are calculated within the sliding time window. The sliding time window features include the temperature evolution rate in the chamber, the comprehensive heat transfer criterion temperature difference, the cumulative door opening time, the door opening frequency, and the dynamic energy efficiency degradation factor.

[0015] Step C: Run modal recognition;

[0016] Based on the sliding time window characteristics and preset boundary conditions, the current operating mode of the refrigeration equipment is identified. The operating mode includes at least the rapid temperature increase mode, the frequent door opening disturbance mode, the stable energy-saving maintenance mode, the adaptive intelligent defrosting mode, and the post-defrosting heat management mode. When the identification conditions of multiple operating modes are met at the same time, the mode is selected according to the preset priority.

[0017] Step D: Invoking the cooperative control law;

[0018] Based on the identified operating mode, the corresponding actuator collaborative control law is invoked to generate a control vector, which includes the target frequency of the variable frequency compressor, the target speed of the evaporator fan, and the on / off state of the defrosting heating wire.

[0019] Step E: Safety constraint correction;

[0020] Before the control vector is output to the actuator, the frequency modulation slope constraint of the variable frequency compressor, the minimum start-stop time constraint of the variable frequency compressor, and the heat exchange abnormal load reduction protection constraint are superimposed to obtain the final control command and output to the corresponding actuator.

[0021] Further, in step A, the sampling period is denoted as... In the Construct a multidimensional state flow data vector at each sampling time. :

[0022]

[0023] in, This refers to the temperature inside the chamber. This refers to the temperature of the evaporator tube wall. Ambient temperature; The door is in open / closed state. This indicates that the door is closed. Indicates opening the door; This refers to the operating current of the variable frequency compressor.

[0024] Furthermore, in step B, at the current sampling time Establish a sliding time window of length N. The calculation of the sliding time window features specifically includes:

[0025] The rate of change of temperature within the chamber is calculated using the slope of the first-order least squares fit of the temperature within the chamber relative to the sampling time within a sliding time window.

[0026]

[0027] in, and The sampling point number and its arithmetic mean within the sliding time window. This represents the average temperature inside the chamber over the sliding time window.

[0028] The heat transfer comprehensive criterion temperature difference is constructed based on the temperature difference between the chamber temperature and the evaporator tube wall temperature at the current sampling time:

[0029]

[0030] The cumulative door opening time and door opening frequency within the sliding time window are expressed as follows:

[0031]

[0032]

[0033] in, To calculate the cumulative opening time, Frequency of door opening;

[0034] The dynamic energy efficiency degradation factor is used to characterize the temperature drop effect inside the chamber corresponding to a unit of input electrical power, and is expressed as:

[0035]

[0036] In the formula, Supply voltage to the refrigeration equipment. To avoid small positive quantities with a denominator of zero.

[0037] Further, in step C:

[0038] The identification criteria for the frequent door opening disturbance mode include: the cumulative door opening duration within the sliding time window. Reaching the preset cumulative time threshold, or the number of times the door is opened. The preset door opening frequency threshold has been reached;

[0039] The identification conditions for the rapid temperature increase mode include: the temperature inside the chamber is higher than the upper boundary of the set temperature value, and the time evolution rate of the temperature inside the chamber is... This indicates that the temperature inside the chamber is either rising or not falling sufficiently.

[0040] The identification conditions for the stable energy-saving maintenance mode include: the internal temperature is within the set temperature accuracy range, there is no door opening action within the sliding time window, and the absolute value of the internal temperature time evolution rate is... Less than the preset stability threshold;

[0041] The triggering conditions for the adaptive intelligent defrosting mode include: the first Continuous operation time of the variable frequency compressor at each sampling moment Achieve basic safe operating time Afterwards, the comprehensive heat transfer criterion temperature difference Greater than or equal to the dynamic temperature difference threshold Furthermore, dynamic energy efficiency degradation factor Less than or equal to the preset energy efficiency threshold :

[0042]

[0043] in The dynamic temperature difference threshold, corrected for ambient temperature, is expressed as:

[0044]

[0045] in, As the reference temperature difference threshold, This is the ambient temperature correction factor. The reference ambient temperature;

[0046] The exit conditions for the adaptive intelligent defrosting mode to the post-defrosting heat management mode include: evaporator tube wall temperature. Reaching the preset defrost exit temperature limit Or, the evaporator tube wall temperature change rate exhibits a preset negative abrupt change characteristic, i.e., one of the following conditions is met:

[0047]

[0048] in, This is a preset threshold for the abrupt change rate of temperature.

[0049] Further, in step C:

[0050] When the identification conditions of multiple operating modes are met simultaneously, the mode selection is performed according to the following preset priority: the adaptive intelligent defrosting mode and the post-defrosting heat management mode take priority over the frequent door opening disturbance mode, rapid temperature increase mode and stable energy-saving maintenance mode under the refrigeration category; the frequent door opening disturbance mode takes priority over the rapid temperature increase mode and the stable energy-saving maintenance mode.

[0051] Further, in step D, the corresponding control vector of the actuator cooperative control law is expressed as:

[0052]

[0053] in, The target frequency of the variable frequency compressor corresponds to different operating modes; The target speed of the evaporator fan; The defrosting heating wire is in the on / off state. This indicates that the defrosting heating element is energized. This indicates that the defrosting heating element is de-energized;

[0054] Define the temperature control deviation inside the chamber as:

[0055]

[0056] in, Set the internal temperature value.

[0057] Furthermore, the coordinated control laws for actuators corresponding to different operating modes are as follows:

[0058] Frequent door opening disturbance mode:

[0059] Under the frequent door opening disturbance mode, when the door is open, the defrost heating wire remains de-energized, the evaporator fan stops to reduce the escape of cold air from the chamber to the outside environment, and the variable frequency compressor maintains the target frequency before door opening or operates according to a preset limiting law. The corresponding control vector is expressed as:

[0060]

[0061] in, This is the minimum permissible operating frequency for the variable frequency compressor. This refers to the maximum allowable frequency of the variable frequency compressor during door opening. Indicates the variable Limit to the lower limit and upper limit between;

[0062] When the door switch state changes from open to closed, it depends on the duration of this opening. And the calculation of the feedforward frequency compensation amount for the variable frequency compressor based on the temperature difference between the ambient temperature and the internal temperature of the chamber:

[0063]

[0064] And generate the recovery control vector after the door is closed:

[0065]

[0066] in, For the feedforward gain of the gate opening disturbance. This is the maximum feedforward frequency compensation amount. To control deviation based on the temperature inside the chamber The established basic target frequency; To achieve the target speed of the evaporator fan during the door-closing recovery phase, the speed is gradually restored from zero to the normal cooling speed according to the preset delay time.

[0067] Rapid warming mode:

[0068] In the aforementioned operating mode, the defrosting heating wire remains de-energized, and the evaporator fan operates at a preset high speed. The target frequency of the variable frequency compressor in the rapid temperature-up mode is calculated based on the temperature control deviation within the chamber and the rate of temperature evolution within the chamber.

[0069]

[0070] The corresponding control vector is:

[0071]

[0072] in, To rapidly increase the base frequency, This is the minimum operating frequency of the variable frequency compressor under rapid heating mode. This refers to the maximum permissible operating frequency of the variable frequency compressor. and These are the temperature deviation gain and the temperature rise trend compensation gain, respectively. Set a target high speed for the evaporator fan;

[0073] When the temperature inside the chamber is too high or the temperature inside the chamber does not drop sufficiently, the target frequency of the inverter compressor is increased; when the temperature inside the chamber is close to the set temperature range, the target frequency is gradually reduced according to the frequency adjustment slope constraint of the inverter compressor to avoid overshoot of the temperature inside the chamber.

[0074] Stable energy-saving maintenance mode:

[0075] Under the stable energy-saving maintenance mode, the defrosting heating wire remains de-energized; the target frequency of the inverter compressor is slightly adjusted in a closed-loop manner based on the temperature control deviation inside the chamber.

[0076]

[0077] The target speed of the evaporator fan is determined based on the heat transfer load:

[0078]

[0079] The corresponding control vector is:

[0080]

[0081] in, To maintain the target frequency of the variable frequency compressor under stable and energy-saving mode, and These are the energy-saving reference frequency for the variable frequency compressor and the energy-saving target speed for the evaporator fan, respectively. , and The preset adjustment coefficient; To ensure stable and energy-efficient operation of the variable frequency compressor, the highest frequency under the specified mode is maintained. and These are the lower and upper limits of the target speed for the evaporator fan, respectively.

[0082] When the temperature inside the chamber is within the preset shutdown dead zone centered on the set temperature, the variable frequency compressor is allowed to stop or switch to the lowest frequency operation; when the temperature deviates from the shutdown dead zone, the variable frequency compressor and evaporator fan operate according to the control vector corresponding to formula (19), thereby reducing energy consumption while ensuring temperature accuracy.

[0083] Adaptive intelligent defrosting mode:

[0084] In the adaptive intelligent defrosting mode, the variable frequency compressor and evaporator fan are stopped, and the defrosting heating wire is turned on. The corresponding control vector is:

[0085]

[0086] The evaporator tube wall temperature is continuously monitored during the defrosting process. And its rate of change; when any of the following conditions are met: the evaporator tube wall temperature reaches the preset defrost exit temperature upper limit, the evaporator tube wall temperature change rate exhibits a preset negative abrupt change characteristic, or the defrost duration reaches the preset maximum defrost time, the defrost heating wire is switched from the energized state to the de-energized state, that is:

[0087]

[0088] Post-defrost heat management mode:

[0089] In the post-defrost heat management mode, the defrost heating wire remains de-energized; in the first management phase after defrosting, the evaporator fan remains stopped, and the variable frequency compressor starts at a preset low frequency. The corresponding control vector is:

[0090]

[0091] Subsequently, the target frequency of the inverter compressor in the heat management mode after stepped frequency increase defrosting is:

[0092]

[0093] in, This refers to the starting frequency of the inverter compressor after defrosting. This refers to the step size for a single frequency increase. This represents the number of frequency boosts that have been performed since the end of the defrosting process. This is the upper limit of the frequency of the variable frequency compressor during the heat management phase after defrosting.

[0094] Only if the evaporator tube wall temperature meets the following conditions:

[0095]

[0096] Furthermore, if the above conditions are maintained continuously for a preset evaporator fan access delay, the evaporator fan will gradually resume operation from a stopped state, and the corresponding control vector will switch as follows:

[0097]

[0098] in, To preset the evaporator fan access temperature, The target speed of the evaporator fan during the heat management phase after defrosting;

[0099] The speed is gradually increased from zero or low speed to normal cooling speed according to the preset slope to reduce the direct entry of residual heat from the evaporator into the cabinet.

[0100] When the evaporator tube wall temperature, the internal temperature, and the rate of change of the internal temperature all return to the corresponding normal cooling range, the defrost heat management mode is exited, and the mode is switched to rapid temperature increase mode or stable energy-saving maintenance mode according to the current internal temperature.

[0101] Furthermore, in step E, before the control vector is output to the actuator, the following safety constraint correction is applied:

[0102] Frequency conversion compressor frequency regulation slope constraint:

[0103] In the formula, The allowable frequency modulation slope for the variable frequency compressor;

[0104] Minimum start-stop time constraint for variable frequency compressors:

[0105] When the control vector requires the variable frequency compressor to switch from the running state to the stop state, the minimum start-up time constraint should be met; when the control vector requires the variable frequency compressor to switch from the stop state to the running state, the minimum stop time constraint should be met.

[0106] In the formula, For the first The continuous downtime of the variable frequency compressor at each sampling moment. and These are the shortest startup time and the shortest downtime, respectively.

[0107] Abnormal heat transfer load reduction protection constraints:

[0108] When the comprehensive heat transfer criterion temperature difference The abnormal temperature difference is greater than or equal to the preset abnormal temperature difference threshold, and the dynamic energy efficiency degradation factor is greater than or equal to the preset abnormal temperature difference threshold. When the energy efficiency threshold is less than or equal to the preset abnormal energy efficiency threshold, it is determined to be an abnormal heat exchange state, and the target frequency of the variable frequency compressor is reduced for protection.

[0109] in, The target frequency of the variable frequency compressor is adjusted to meet safety constraints. This is the upper limit of the preset protection frequency under abnormal heat exchange conditions.

[0110] A refrigeration equipment operation mode sensing and switching control system includes: a data acquisition module, a sliding time window feature calculation module, an operation mode identification and switching management module, a collaborative control decision and execution mechanism drive module, and a safety constraint correction module, which respectively perform steps A to E of the above-mentioned refrigeration equipment operation mode sensing and switching control method.

[0111] A refrigeration device includes a housing, an evaporator, a variable frequency compressor, an evaporator fan, a defrosting heating wire, a sensor, and a controller, wherein the controller is configured to execute the above-described operating mode sensing and switching control method for the refrigeration device.

[0112] The present invention has the following beneficial effects:

[0113] (1) Temperature control accuracy and recovery speed are significantly improved: By identifying the operating mode through the sliding time window feature and switching according to the preset priority, the control changes from a single temperature threshold response to a patterned decision-making for dynamic working conditions. It can detect the temperature change trend inside the cabinet caused by door opening, replenishment and load change in advance, avoid response lag and control action conflict. Compared with single temperature threshold control, the temperature inside the cabinet recovers faster and fluctuates less.

[0114] (2) Refrigeration operation takes into account both rapid recovery and energy saving: when the door is opened, the defrosting heating wire is de-energized and the evaporator fan stops to maintain the cooling capacity. After the door is closed, the heat load is quickly offset by the feedforward compensation of the variable frequency compressor and the fan delay recovery. The rapid temperature pulling mode cools down quickly and avoids overshoot. The stable energy-saving mode reduces energy consumption while ensuring temperature accuracy, which is more energy-efficient than the conventional fixed speed operation mode.

[0115] (3) Precise defrosting timing and stable temperature after defrosting: The defrosting status is judged by the temperature difference and dynamic energy efficiency degradation factor in combination with the heat transfer comprehensive criterion, so that the defrosting timing matches the actual degree of frost. Compared with fixed-time defrosting, it can reduce ineffective defrosting when there is little frost and avoid defrosting delay when there is severe frost. After defrosting, low-frequency pre-cooling and fan access control prevent residual heat and water vapor from entering the cabinet, making the cabinet environment more stable and reliable.

[0116] (4) Safe and reliable operation and extended equipment life: By adjusting the frequency slope, the shortest start-up and shutdown time and heat exchange abnormal load protection constraints, the compressor frequency changes and frequent start-ups and shutdowns are avoided, and current surges, mechanical shocks and system oscillations are reduced; automatic load reduction protection is provided when heat exchange is abnormal, ensuring long-term stable operation of the equipment. Attached Figure Description

[0117] Figure 1 This is a schematic diagram of the overall architecture of the refrigeration equipment operation mode sensing and switching control system provided in an embodiment of the present invention. Detailed Implementation

[0118] To make the technical solution, the technical problem solved, and the beneficial effects of this invention clearer, the technical solution of this invention will be specifically described in conjunction with the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0119] This invention uses a variable frequency refrigerator as Example 1 and a variable frequency freezer as Example 2. Both examples employ the refrigeration equipment operation mode sensing and switching control method of this invention. Example 1 details the implementation process of the method and verifies its technical effectiveness through comparative experiments. Example 2 only describes the equipment parameters and control parameter values ​​that differ from Example 1; the rest is the same as Example 1 and will not be repeated. It should be understood that the following examples are provided for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0120] In Example 1, a variable frequency refrigerator is used as the implementation object. This variable frequency refrigerator is a four-door solid door refrigerator with an effective volume of 936L, using R290 refrigerant, and the internal temperature is set to 3℃. The frequency range of the variable frequency compressor is 53Hz~150Hz; the evaporator fan is a variable speed fan with an adjustable speed range of 1200rpm~2500rpm; the rated power of the defrost heating wire is 420W; the sampling period of the control system is 1s, and the control period is 5s.

[0121] A mode-sensing switching control method for refrigeration equipment, such as Figure 1 As shown, it includes the following steps:

[0122] Step A: Multidimensional state flow data acquisition;

[0123] Multidimensional state flow data of the refrigeration equipment is collected according to a fixed sampling period. This multidimensional state flow data includes at least the internal temperature, evaporator wall temperature, ambient temperature, door open / close status, and inverter compressor operating current. The sampling period is denoted as [missing information]. In the Construct a multidimensional state flow data vector at each sampling time. :

[0124]

[0125] in, This refers to the temperature inside the chamber. This refers to the temperature of the evaporator tube wall. Ambient temperature; The door is in open / closed state. This indicates that the door is closed. Indicates opening the door; This refers to the operating current of the variable frequency compressor.

[0126] Step B: Calculation of sliding time window features;

[0127] A sliding time window is constructed based on the multidimensional state flow data, and the sliding time window features are calculated within the sliding time window. The sliding time window features include the temperature evolution rate in the chamber, the comprehensive heat transfer criterion temperature difference, the cumulative door opening time, the door opening frequency, and the dynamic energy efficiency degradation factor.

[0128] At the current sampling time Establish a length of Sliding time window The calculation of the sliding time window features specifically includes:

[0129] The rate of change of temperature within the chamber is calculated using the slope of the first-order least squares fit of the temperature within the chamber relative to the sampling time within a sliding time window.

[0130]

[0131] in, and The sampling point number and its arithmetic mean within the sliding time window. This represents the average temperature inside the chamber over the sliding time window.

[0132] The heat transfer comprehensive criterion temperature difference is constructed based on the temperature difference between the chamber temperature and the evaporator tube wall temperature at the current sampling time:

[0133]

[0134] The cumulative door opening time and door opening frequency within the sliding time window are expressed as follows:

[0135]

[0136]

[0137] in, To calculate the cumulative opening time, Frequency of door opening;

[0138] The dynamic energy efficiency degradation factor is used to characterize the temperature drop effect inside the chamber corresponding to a unit of input electrical power, and is expressed as:

[0139]

[0140] In the formula, Supply voltage to the refrigeration equipment. =0.002 is used to avoid small positive quantities with a denominator of zero.

[0141] Step C: Run modal recognition;

[0142] Based on the sliding time window characteristics and preset boundary conditions, the current operating mode of the refrigeration equipment is identified. The operating mode includes at least the rapid temperature increase mode, the frequent door opening disturbance mode, the stable energy-saving maintenance mode, the adaptive intelligent defrosting mode, and the post-defrosting heat management mode. When the identification conditions of multiple operating modes are met at the same time, the mode is selected according to the preset priority.

[0143] The identification criteria for the frequent door opening disturbance mode include: the cumulative door opening duration within the sliding time window. Reaching the preset cumulative time threshold of 20 seconds, or the door opening frequency The preset door opening frequency threshold is reached 3 times;

[0144] The identification conditions for the rapid temperature increase mode include: the temperature inside the chamber is 5°C higher than the upper boundary of the temperature setpoint, and the temperature evolution rate inside the chamber is [missing information]. This indicates that the temperature inside the chamber is either rising or not falling sufficiently. In this embodiment, a temperature evolution rate greater than 0.005℃ / s is considered a rising temperature, and a temperature evolution rate greater than −0.005℃ / s and less than 0 is considered an insufficient temperature drop.

[0145] The identification conditions for the stable energy-saving maintenance mode include: the internal temperature is within the set temperature accuracy range of 1℃ to 5℃, there is no door opening action within the sliding time window, and the absolute value of the internal temperature time evolution rate is... Less than the preset stability threshold of 0.005℃ / s;

[0146] The triggering conditions for the adaptive intelligent defrosting mode include: the first Continuous operation time of the variable frequency compressor at each sampling moment Achieve basic safe operating time Afterwards, the comprehensive heat transfer criterion temperature difference Greater than or equal to the dynamic temperature difference threshold Furthermore, dynamic energy efficiency degradation factor Less than or equal to the preset energy efficiency threshold :

[0147]

[0148] in The dynamic temperature difference threshold, corrected for ambient temperature, is expressed as:

[0149]

[0150] in, The baseline temperature difference threshold is 8℃. This is the ambient temperature correction factor. The baseline ambient temperature is 25℃;

[0151] The exit conditions for the adaptive intelligent defrosting mode to the post-defrosting heat management mode include: evaporator tube wall temperature. Reaching the preset defrost exit temperature limit Or, the evaporator tube wall temperature change rate exhibits a preset negative abrupt change characteristic, i.e., one of the following conditions is met:

[0152]

[0153] in, To preset the threshold for the abrupt change rate of temperature, .

[0154] Further, in step C:

[0155] When the identification conditions of multiple operating modes are met simultaneously, the mode selection is performed according to the following preset priority: the adaptive intelligent defrosting mode and the post-defrosting heat management mode take priority over the frequent door opening disturbance mode, rapid temperature increase mode and stable energy-saving maintenance mode under the refrigeration category; the frequent door opening disturbance mode takes priority over the rapid temperature increase mode and the stable energy-saving maintenance mode.

[0156] Step D: Invoking the cooperative control law;

[0157] Based on the identified operating mode, the corresponding actuator collaborative control law is invoked to generate a control vector, which includes the target frequency of the variable frequency compressor, the target speed of the evaporator fan, and the on / off state of the defrosting heating wire.

[0158] The corresponding control vector of the actuator cooperative control law is expressed as:

[0159]

[0160] in, The target frequency for the variable frequency compressor is [frequency value], and the frequency adjustment range is [range]. Each has a different operating mode; The target speed of the evaporator fan, in the range of ; The defrosting heating wire is in the on / off state. This indicates that the defrosting heating element is energized. This indicates that the defrosting heating element is de-energized;

[0161] Define the temperature control deviation inside the chamber as:

[0162]

[0163] in, Set the internal temperature value.

[0164] Furthermore, the coordinated control laws for actuators corresponding to different operating modes are as follows:

[0165] Frequent door opening disturbance mode:

[0166] Under the frequent door opening disturbance mode, when the door is open, the defrost heating wire remains de-energized, the evaporator fan stops to reduce the escape of cold air from the chamber to the outside environment, and the variable frequency compressor maintains the target frequency before door opening or operates according to a preset limiting law. The corresponding control vector is expressed as:

[0167]

[0168] in, The minimum permissible operating frequency for a variable frequency compressor is 53Hz. The maximum allowable frequency of the variable frequency compressor during door opening is 80Hz; Indicates the variable Limit to the lower limit and upper limit between;

[0169] When the door switch state changes from open to closed, it depends on the duration of this opening. And the calculation of the feedforward frequency compensation amount for the variable frequency compressor based on the temperature difference between the ambient temperature and the internal temperature of the chamber:

[0170]

[0171] And generate the recovery control vector after the door is closed:

[0172]

[0173] in, For the feedforward gain of the gate perturbation, ; The maximum feedforward frequency compensation is 30Hz; To control deviation based on the temperature inside the chamber The established basic target frequency; The target speed of the evaporator fan during the door-closing recovery phase is 1500 rpm, and it gradually recovers from zero to the normal cooling speed according to the preset delay time of 30 seconds;

[0174] Rapid warming mode:

[0175] In the aforementioned operating mode, the defrosting heating wire remains de-energized, and the evaporator fan operates at a preset high speed. The target frequency of the variable frequency compressor in the rapid temperature-up mode is calculated based on the temperature control deviation within the chamber and the rate of temperature evolution within the chamber.

[0176]

[0177] The corresponding control vector is:

[0178]

[0179] in, The base frequency for rapid temperature increase is 90Hz. The minimum operating frequency of the variable frequency compressor in the rapid heating mode is 60Hz. The maximum permissible operating frequency for the variable frequency compressor is 150Hz; and These are the temperature deviation gain and the temperature rise trend compensation gain, respectively. The target high speed for the evaporator fan is preset to 2500 rpm;

[0180] When the temperature inside the chamber is too high or the temperature inside the chamber does not drop sufficiently, the target frequency of the inverter compressor is increased; when the temperature inside the chamber is close to the set temperature range, the target frequency is gradually reduced according to the frequency adjustment slope constraint of the inverter compressor to avoid overshoot of the temperature inside the chamber.

[0181] Stable energy-saving maintenance mode:

[0182] Under the stable energy-saving maintenance mode, the defrosting heating wire remains de-energized; the target frequency of the inverter compressor is slightly adjusted in a closed-loop manner based on the temperature control deviation inside the chamber.

[0183]

[0184] The target speed of the evaporator fan is determined based on the heat transfer load:

[0185]

[0186] The corresponding control vector is:

[0187]

[0188] in, To maintain the target frequency of the variable frequency compressor under stable and energy-saving mode, and These are the energy-saving reference frequency for the variable frequency compressor and the energy-saving target speed for the evaporator fan, respectively. , and The preset adjustment coefficient; To ensure stable energy saving of the variable frequency compressor, the highest frequency under the mode is maintained at 100Hz; and These are the lower and upper limits of the target speed for the evaporator fan, respectively.

[0189] When the temperature inside the chamber is within the preset zone (3℃±1℃) centered on the set temperature, the variable frequency compressor is allowed to stop or switch to the lowest frequency operation; when the temperature deviates from the stop dead zone, the variable frequency compressor and evaporator fan operate according to the control vector corresponding to formula (19), thereby reducing energy consumption while ensuring temperature accuracy.

[0190] Adaptive intelligent defrosting mode:

[0191] In the adaptive intelligent defrosting mode, the variable frequency compressor and evaporator fan are stopped, and the defrosting heating wire is turned on. The corresponding control vector is:

[0192]

[0193] The evaporator tube wall temperature is continuously monitored during the defrosting process. And its rate of change; when any of the following conditions are met: the evaporator tube wall temperature reaches the preset defrost exit temperature upper limit of 1℃, the evaporator tube wall temperature change rate exhibits a preset negative abrupt change characteristic, or the defrost duration reaches the preset maximum defrost time of 15 minutes, the defrost heating wire is switched from the energized state to the de-energized state, that is:

[0194]

[0195] Post-defrost heat management mode:

[0196] In the post-defrost heat management mode, the defrost heating wire remains de-energized; in the first management phase after defrosting, the evaporator fan remains stopped, and the variable frequency compressor starts at a preset low frequency. The corresponding control vector is:

[0197]

[0198] Subsequently, the target frequency of the inverter compressor in the heat management mode after stepped frequency increase defrosting is:

[0199]

[0200] in, The starting frequency of the inverter compressor after defrosting is 55Hz. The single upsampling step size is 5Hz. This refers to the number of frequency boosts that have been performed since the end of defrosting, with a maximum of 10. The upper limit of the frequency of the inverter compressor during the heat management stage after defrosting is 105Hz;

[0201] Only if the evaporator tube wall temperature meets the following conditions:

[0202]

[0203] Furthermore, if the above conditions are maintained continuously for a preset evaporator fan access delay of 30 seconds, the evaporator fan will gradually resume operation from a stopped state, and the corresponding control vector will switch as follows:

[0204]

[0205] in, The preset evaporator fan inlet temperature is 0℃. The target speed for the evaporator fan during the heat management phase after defrosting is 2000 rpm;

[0206] The speed is gradually increased from zero or low speed to normal cooling speed according to the preset slope to reduce the direct entry of residual heat from the evaporator into the cabinet.

[0207] When the evaporator tube wall temperature, the internal temperature, and the rate of change of the internal temperature all return to the corresponding normal cooling range, the defrost heat management mode is exited, and the mode is switched to rapid temperature increase mode or stable energy-saving maintenance mode according to the current internal temperature.

[0208] Step E: Safety constraint correction;

[0209] Before the control vector is output to the actuator, the frequency modulation slope constraint of the variable frequency compressor, the minimum start-stop time constraint of the variable frequency compressor, and the heat exchange abnormal load reduction protection constraint are superimposed to obtain the final control command and output to the corresponding actuator.

[0210] Before the control vector is output to the actuator, the following safety constraint correction is applied:

[0211] Frequency conversion compressor frequency regulation slope constraint:

[0212] In the formula, Allowable frequency modulation slope for variable frequency compressors ;

[0213] Minimum start-stop time constraint for variable frequency compressors:

[0214] When the control vector requires the variable frequency compressor to switch from the running state to the stop state, the minimum start-up time constraint should be met; when the control vector requires the variable frequency compressor to switch from the stop state to the running state, the minimum stop time constraint should be met.

[0215] In the formula, For the first The continuous downtime of the variable frequency compressor at each sampling moment. and These are the shortest startup time and the shortest downtime, respectively.

[0216] Abnormal heat transfer load reduction protection constraints:

[0217] When the comprehensive heat transfer criterion temperature difference The abnormal temperature difference is greater than or equal to the preset abnormal temperature difference threshold of 12℃, and the dynamic energy efficiency degradation factor is greater than or equal to the preset abnormal temperature difference threshold of 12℃. Less than or equal to the preset abnormal energy efficiency threshold The system was identified as experiencing an abnormal heat exchange condition, and load reduction protection was applied to the target frequency of the variable frequency compressor.

[0218] in, The target frequency of the variable frequency compressor is adjusted to meet safety constraints. The preset protection frequency limit is 100Hz under abnormal heat exchange conditions.

[0219] To verify the technical effectiveness of the method of the present invention, a comparative experiment was conducted using the variable frequency refrigerated cabinet of this embodiment as the implementation object. The test environment and test methods are as follows:

[0220] The refrigeration equipment in this embodiment is a four-door solid-door freezer. The test conditions are performed according to Clause 5.2.5 of GB26920—2024 and the test conditions specified in SB / T10794.2—2012, with a climate type of 4. The ambient temperature is controlled at 25℃±1℃, and the relative humidity is controlled at 60%RH±5%RH. The test power supply, instrument accuracy, and data acquisition method all meet the standard requirements. The test load uses test packages and M-packages that meet the requirements of Appendix A of GB26920—2024. Before the test, the verification chamber temperature meets the requirements of the selected climate type and temperature classification (M1).

[0221] The power consumption test was conducted continuously for 24 hours according to the test conditions specified in SB / T10794.2—2012, and the test procedure met the standard requirements. The 24-hour test included door opening and use according to the door opening and use method specified in GB26920—2024: the door was opened in a 12-hour cycle within 24 hours, and this 12-hour door opening cycle was located at the beginning of the test; before the start of the 12-hour door opening cycle, each door was opened once in sequence for 3 minutes each time; all doors were opened 10 times per hour, with multiple doors opening alternately; the opening angle of the hinged door exceeded 60°; the total time for a single door opening was 15 seconds, during which the door remained open for at least 13 seconds.

[0222] To objectively evaluate the technical effectiveness of the method of this invention, a comparative experiment was designed on the same variable frequency refrigerated cabinet: During the baseline period, the original control strategy was used (manufacturer drop-in variable frequency mode, hysteresis start-stop control of internal temperature, stopping when the temperature drops to 1℃ and starting when it rises to 5℃, evaporator fan fixed at 2000rpm, defrosting once every 6 hours for 4 minutes each time); during the new strategy period, the method of this invention (steps A-E) was used. Both periods were conducted under the same environmental conditions, the same load, and the same door opening method, fully complying with the operating conditions specified in national standard GB26920-2024, and were run continuously for 24 hours. The experimental results are as follows:

[0223] (1) Temperature control accuracy and recovery speed: During the baseline period, the peak value of the temperature fluctuation inside the chamber was 2.5℃, and the peak value of the chamber temperature after the door opening disturbance was 3.0℃, with a temperature recovery time of 2.8min. During the new strategy period, the peak value of the temperature fluctuation inside the chamber decreased to 1.8℃, a reduction of 28%, and the peak value of the chamber temperature after the door opening disturbance decreased to 2.6℃, with the temperature recovery time shortened to 1.7min, a reduction of 39.3%. This indicates that the present invention identifies the operating mode by using the sliding time window feature and switches it according to priority. When the door is opened, the evaporator fan stops to reduce the leakage of cold energy, and after the door is closed, the temperature is recovered faster and with less fluctuation through feedforward compensation by the variable frequency compressor and delayed recovery by the fan.

[0224] (2) Rapid recovery and energy saving: The cumulative power consumption during the baseline period of 24 hours was 3.26 kWh, and the power consumption during the new strategy period was 2.68 kWh, with an energy saving rate of about 17.8%. This shows that the present invention can quickly cool down in the rapid heating mode and avoid overshoot, and reduce the compressor frequency and fan speed in the stable energy-saving maintenance mode, which is more energy-efficient than the fixed speed operation mode.

[0225] (3) Precise defrosting timing and stable temperature after defrosting: During the baseline period, defrosting was triggered 4 times in 24 hours, and the temperature rebound after defrosting was 4.2℃; during the new strategy period, defrosting was triggered 2 times in 24 hours, a reduction of 50%, and the temperature rebound after defrosting was reduced to 2.8℃, a reduction of 33.3%. This indicates that the present invention judges the frosting state by combining the temperature difference of the heat transfer comprehensive criterion and the dynamic energy efficiency degradation factor, reducing ineffective defrosting when there is little frost, and suppresses residual heat from entering the chamber and reduces temperature rebound by low-frequency pre-cooling after defrosting and fan access control.

[0226] (4) Safe and reliable operation and long equipment life: During the baseline period, the peak compressor frequency change rate was 7 Hz / s, the peak compressor operating current was 4.1 A, and there were 25 impact / oscillation events; during the new strategy period, the peak compressor frequency change rate decreased to 4 Hz / s, a reduction of 42.9%, the peak compressor operating current decreased to 3.5 A, and the number of impact / oscillation events decreased to 12, a reduction of 52%. This shows that the present invention avoids compressor frequency mutations and frequent start-stops by constraining the frequency modulation slope, the shortest start-stop time, and the heat exchange abnormal load reduction protection, thereby reducing current impact, mechanical impact, and system oscillation.

[0227] Example 2 uses a variable frequency freezer. This example only describes the parts that differ from Example 1; the rest will not be repeated.

[0228] This variable frequency freezer is a four-door solid door freezer with an effective volume of 936L. It uses R290 refrigerant, and the internal temperature is set at −19℃. The rated power of the defrosting heating wire is 800W. The frequency range of the variable frequency compressor is 66.7Hz~150Hz (corresponding to a speed of 2000rpm~4500rpm). The evaporator fan speed range is 1200rpm~2500rpm. The sampling period of the control system is 1s, and the control period is 5s. Since the internal temperature setting is different from that in Example 1, the parameters related to the temperature setting value in steps C to E (the upper boundary of the temperature setting value, the accuracy range of the setting temperature, and the reference frequency of each mode, etc.) are adjusted accordingly with the setting temperature. The remaining parameters and control process are the same as in Example 1 and will not be repeated.

[0229] The door opening test was conducted in accordance with the national standard GB26920-2024. The difference from Example 1 is that all doors were opened 6 times per hour, with a total opening time of 6 seconds per opening, and the doors were kept open for at least 4 seconds during the opening; the rest were the same.

[0230] A comparative experiment was conducted using the existing control strategy as a baseline and the method of this invention as the new strategy. After door opening disturbance, the peak temperature of the freezer (the deviation from the set temperature) decreased from 5℃ to 3.6℃; the cumulative power consumption over 24 hours decreased from 8.42 kWh to 6.69 kWh, an energy saving rate of approximately 20.5%; the number of defrost triggers over 24 hours decreased from 4 to 2. The number of shock / oscillation events decreased from 34 to 21, a reduction of 38.2%. This indicates that the method of this invention can also effectively suppress door opening disturbances, reduce energy consumption, reduce ineffective defrosting, and reduce equipment impact in freezers.

[0231] In summary, to address the problems of control response lag, inaccurate defrosting timing, post-defrosting temperature rebound, and current surges and system oscillations caused by uncoordinated compressor and fan actions in refrigeration equipment under conditions such as frequent door opening, concentrated replenishment, frosting, defrosting withdrawal, and post-defrosting recovery, this invention proposes a mode-sensing switching control method for refrigeration equipment. This method, through steps A to E, switches between operating modes according to preset priorities, including frequent door opening disturbances, rapid temperature increase, stable energy-saving maintenance, adaptive intelligent defrosting, and post-defrosting heat management. Before the control vector output, constraints on the variable frequency compressor's frequency modulation slope, minimum start-stop time, and heat exchange abnormal load reduction protection are superimposed. This ensures both temperature control accuracy and recovery speed while also balancing energy-saving operation, achieving precise defrosting timing and stable post-defrosting temperature, and reducing current surges, mechanical shocks, and system oscillations, thus guaranteeing long-term safe and reliable equipment operation. Comparative experiments show that this method effectively suppresses door opening disturbances, reduces operating energy consumption, minimizes ineffective defrosting, and reduces equipment impact in both variable frequency refrigerators and freezers. This invention does not rely on adding new valve actuators. It mainly utilizes existing status information of refrigeration equipment, such as internal temperature, evaporator wall temperature, ambient temperature, door open / close status, and variable frequency compressor operating current. By upgrading the control program, it can achieve operating mode sensing and switching control. It is applicable to various types of refrigeration equipment with variable frequency compressors and evaporator fans, such as refrigerators, freezers, kitchen refrigerators and freezers, convenience store display cases, and beverage display cases. It has good engineering adaptability and promotion and application value.

[0232] Those skilled in the art should understand that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Technical features in different embodiments can be freely combined according to actual needs to achieve better technical effects. Based on the technical teachings provided by this invention, relevant researchers can reasonably deduce and implement other feasible technical variations. It should be particularly noted that modifications to the technical solutions of the described embodiments, or the use of equivalent alternatives to replace some technical features, should be considered within the scope of protection of this application, as long as they do not depart from the core concept of the technical solution.

Claims

1. A method for sensing and switching control of operating modes of a refrigeration device, characterized in that, Includes the following steps: Step A: Multidimensional state flow data acquisition; Multidimensional state flow data of the refrigeration equipment is collected according to a fixed sampling period. The multidimensional state flow data includes at least the internal temperature of the chamber, the evaporator tube wall temperature, the ambient temperature, the door opening and closing status, and the operating current of the variable frequency compressor. Step B: Calculation of sliding time window features; A sliding time window is constructed based on the multidimensional state flow data, and the sliding time window features are calculated within the sliding time window. The sliding time window features include the temperature evolution rate in the chamber, the comprehensive heat transfer criterion temperature difference, the cumulative door opening time, the door opening frequency, and the dynamic energy efficiency degradation factor. Step C: Run modal recognition; Based on the sliding time window characteristics and preset boundary conditions, the current operating mode of the refrigeration equipment is identified. The operating mode includes at least the rapid temperature increase mode, the frequent door opening disturbance mode, the stable energy-saving maintenance mode, the adaptive intelligent defrosting mode, and the post-defrosting heat management mode. When the identification conditions of multiple operating modes are met at the same time, the mode is selected according to the preset priority. Step D: Invoking the cooperative control law; Based on the identified operating mode, the corresponding actuator collaborative control law is invoked to generate a control vector, which includes the target frequency of the variable frequency compressor, the target speed of the evaporator fan, and the on / off state of the defrosting heating wire. Step E: Safety constraint correction; Before the control vector is output to the actuator, the frequency modulation slope constraint of the variable frequency compressor, the minimum start-stop time constraint of the variable frequency compressor, and the heat exchange abnormal load reduction protection constraint are superimposed to obtain the final control command and output to the corresponding actuator.

2. The method for sensing and switching operation modes of a refrigeration device according to claim 1, characterized in that, In step A, the sampling period is denoted as... In the Construct a multidimensional state flow data vector at each sampling time. : in, This refers to the temperature inside the chamber. This refers to the temperature of the evaporator tube wall. Ambient temperature; The door is in open / closed state. This indicates that the door is closed. Indicates opening the door; This refers to the operating current of the variable frequency compressor.

3. The method for sensing and switching operation modes of a refrigeration device according to claim 2, characterized in that, In step B, at the current sampling time Establish a sliding time window of length N. The calculation of the sliding time window features specifically includes: The rate of change of temperature within the chamber is calculated using the slope of the first-order least squares fit of the temperature within the chamber relative to the sampling time within a sliding time window. in, and The sampling point number and its arithmetic mean within the sliding time window. This represents the average temperature inside the chamber over the sliding time window. The heat transfer comprehensive criterion temperature difference is constructed based on the temperature difference between the chamber temperature and the evaporator tube wall temperature at the current sampling time: The cumulative door opening time and door opening frequency within the sliding time window are expressed as follows: in, To calculate the cumulative opening time, Frequency of door opening; The dynamic energy efficiency degradation factor is used to characterize the temperature drop effect inside the chamber corresponding to a unit of input electrical power, and is expressed as: In the formula, Supply voltage to the refrigeration equipment. To avoid small positive quantities with a denominator of zero.

4. The method for sensing and switching operation modes of a refrigeration device according to claim 3, characterized in that, In step C: The identification criteria for the frequent door opening disturbance mode include: the cumulative door opening duration within the sliding time window. Reaching the preset cumulative time threshold, or the number of times the door is opened. The preset door opening frequency threshold has been reached; The identification conditions for the rapid temperature increase mode include: the temperature inside the chamber is higher than the upper boundary of the set temperature value, and the time evolution rate of the temperature inside the chamber is... This indicates that the temperature inside the chamber is either rising or not falling sufficiently. The identification conditions for the stable energy-saving maintenance mode include: the internal temperature is within the set temperature accuracy range, there is no door opening action within the sliding time window, and the absolute value of the internal temperature time evolution rate is... Less than the preset stability threshold; The triggering conditions for the adaptive intelligent defrosting mode include: the first Continuous operation time of the variable frequency compressor at each sampling moment Achieve basic safe operating time Afterwards, the comprehensive heat transfer criterion temperature difference Greater than or equal to the dynamic temperature difference threshold Furthermore, dynamic energy efficiency degradation factor Less than or equal to the preset energy efficiency threshold : in The dynamic temperature difference threshold, corrected for ambient temperature, is expressed as: in, As the reference temperature difference threshold, This is the ambient temperature correction factor. The reference ambient temperature; The exit conditions for the adaptive intelligent defrosting mode to the post-defrosting heat management mode include: evaporator tube wall temperature. Reaching the preset defrost exit temperature limit Or, the evaporator tube wall temperature change rate exhibits a preset negative abrupt change characteristic, i.e., one of the following conditions is met: in, This is a preset threshold for the abrupt change rate of temperature.

5. The method for sensing and switching operation modes of a refrigeration device according to claim 4, characterized in that, In step C: When the identification conditions of multiple operating modes are met simultaneously, the mode selection is performed according to the following preset priority: the adaptive intelligent defrosting mode and the post-defrosting heat management mode take priority over the frequent door opening disturbance mode, rapid temperature increase mode and stable energy-saving maintenance mode under the refrigeration category; the frequent door opening disturbance mode takes priority over the rapid temperature increase mode and the stable energy-saving maintenance mode.

6. The method for sensing and switching operation modes of a refrigeration device according to claim 5, characterized in that, In step D, the corresponding control vector of the actuator cooperative control law is expressed as: in, The target frequency of the variable frequency compressor corresponds to different operating modes; The target speed of the evaporator fan; The defrosting heating wire is in the on / off state. This indicates that the defrosting heating element is energized. This indicates that the defrosting heating element is de-energized; Define the temperature control deviation inside the chamber as: in, Set the internal temperature value.

7. The method for sensing and switching operation modes of a refrigeration device according to claim 6, characterized in that, The actuator coordination control laws corresponding to different operating modes are as follows: Frequent door opening disturbance mode: Under the frequent door opening disturbance mode, when the door is open, the defrost heating wire remains de-energized, the evaporator fan stops to reduce the escape of cold air from the chamber to the outside environment, and the variable frequency compressor maintains the target frequency before door opening or operates according to a preset limiting law. The corresponding control vector is expressed as: in, This is the minimum permissible operating frequency for the variable frequency compressor. This refers to the maximum allowable frequency of the variable frequency compressor during door opening. Indicates the variable Limit to the lower limit and upper limit between; When the door switch state changes from open to closed, it depends on the duration of this opening. And the calculation of the feedforward frequency compensation amount for the variable frequency compressor based on the temperature difference between the ambient temperature and the internal temperature of the chamber: And generate the recovery control vector after the door is closed: in, For the feedforward gain of the gate opening disturbance. This is the maximum feedforward frequency compensation amount. To control deviation based on the temperature inside the chamber The established basic target frequency; To achieve the target speed of the evaporator fan during the door-closing recovery phase, the speed is gradually restored from zero to the normal cooling speed according to the preset delay time. Rapid warming mode: In the aforementioned operating mode, the defrosting heating wire remains de-energized, and the evaporator fan operates at a preset high speed. The target frequency of the variable frequency compressor in the rapid temperature-up mode is calculated based on the temperature control deviation within the chamber and the rate of temperature evolution within the chamber. The corresponding control vector is: in, To rapidly increase the base frequency, This is the minimum operating frequency of the variable frequency compressor under rapid heating mode. This refers to the maximum permissible operating frequency of the variable frequency compressor. and These are the temperature deviation gain and the temperature rise trend compensation gain, respectively. Set a target high speed for the evaporator fan; When the temperature inside the chamber is too high or the temperature inside the chamber does not drop sufficiently, the target frequency of the inverter compressor is increased; when the temperature inside the chamber is close to the set temperature range, the target frequency is gradually reduced according to the frequency adjustment slope constraint of the inverter compressor to avoid overshoot of the temperature inside the chamber. Stable energy-saving maintenance mode: Under the stable energy-saving maintenance mode, the defrosting heating wire remains de-energized; the target frequency of the inverter compressor is slightly adjusted in a closed-loop manner based on the temperature control deviation inside the chamber. The target speed of the evaporator fan is determined based on the heat transfer load: The corresponding control vector is: in, To maintain the target frequency of the variable frequency compressor under stable and energy-saving mode, and These are the energy-saving reference frequency for the variable frequency compressor and the energy-saving target speed for the evaporator fan, respectively. , and The preset adjustment coefficient; To ensure stable and energy-efficient operation of the variable frequency compressor, the highest frequency under the specified mode is maintained. and These are the lower and upper limits of the target speed for the evaporator fan, respectively. When the temperature inside the chamber is within the preset shutdown dead zone centered on the set temperature, the variable frequency compressor is allowed to stop or switch to the lowest frequency operation; when the temperature deviates from the shutdown dead zone, the variable frequency compressor and evaporator fan operate according to the control vector corresponding to formula (19), thereby reducing energy consumption while ensuring temperature accuracy. Adaptive intelligent defrosting mode: In the adaptive intelligent defrosting mode, the variable frequency compressor and evaporator fan are stopped, and the defrosting heating wire is turned on. The corresponding control vector is: The evaporator tube wall temperature is continuously monitored during the defrosting process. And its rate of change; when any of the following conditions are met: the evaporator tube wall temperature reaches the preset defrost exit temperature upper limit, the evaporator tube wall temperature change rate exhibits a preset negative abrupt change characteristic, or the defrost duration reaches the preset maximum defrost time, the defrost heating wire is switched from the energized state to the de-energized state, that is: Post-defrost heat management mode: In the post-defrost heat management mode, the defrost heating wire remains de-energized; in the first management phase after defrosting, the evaporator fan remains stopped, and the variable frequency compressor starts at a preset low frequency. The corresponding control vector is: Subsequently, the target frequency of the inverter compressor in the heat management mode after stepped frequency increase defrosting is: in, This refers to the starting frequency of the inverter compressor after defrosting. This refers to the step size for a single frequency increase. This represents the number of frequency boosts that have been performed since the end of the defrosting process. This is the upper limit of the frequency of the variable frequency compressor during the heat management phase after defrosting. Only if the evaporator tube wall temperature meets the following conditions: Furthermore, if the above conditions are maintained continuously for a preset evaporator fan access delay, the evaporator fan will gradually resume operation from a stopped state, and the corresponding control vector will switch as follows: in, To preset the evaporator fan access temperature, The target speed of the evaporator fan during the heat management phase after defrosting; The speed is gradually increased from zero or low speed to normal cooling speed according to the preset slope to reduce the direct entry of residual heat from the evaporator into the cabinet. When the evaporator tube wall temperature, the internal temperature, and the rate of change of the internal temperature all return to the corresponding normal cooling range, the defrost heat management mode is exited, and the mode is switched to rapid temperature increase mode or stable energy-saving maintenance mode according to the current internal temperature.

8. The method for sensing and switching operation modes of a refrigeration device according to claim 7, characterized in that: In step E, before the control vector is output to the actuator, the following safety constraint correction is applied: Frequency conversion compressor frequency regulation slope constraint: In the formula, The allowable frequency modulation slope for the variable frequency compressor; Minimum start-stop time constraint for variable frequency compressors: When the control vector requires the variable frequency compressor to switch from the running state to the stop state, the minimum start-up time constraint should be met; when the control vector requires the variable frequency compressor to switch from the stop state to the running state, the minimum stop time constraint should be met. In the formula, For the first The continuous downtime of the variable frequency compressor at each sampling moment. and These are the shortest startup time and the shortest downtime, respectively. Abnormal heat transfer load reduction protection constraints: When the comprehensive heat transfer criterion temperature difference The abnormal temperature difference is greater than or equal to the preset abnormal temperature difference threshold, and the dynamic energy efficiency degradation factor is greater than or equal to the preset abnormal temperature difference threshold. When the energy efficiency threshold is less than or equal to the preset abnormal energy efficiency threshold, it is determined to be an abnormal heat exchange state, and the target frequency of the variable frequency compressor is reduced for protection. in, The target frequency of the variable frequency compressor is adjusted to meet safety constraints. This is the upper limit of the preset protection frequency under abnormal heat exchange conditions.

9. A mode-sensing and switching control system for refrigeration equipment, characterized in that, include: The data acquisition module, the sliding time window feature calculation module, the operating mode recognition and switching management module, the collaborative control decision and execution mechanism driving module, and the safety constraint correction module shall respectively perform steps A to E of the operating mode sensing and switching control method for a refrigeration device as described in any one of claims 1-8.

10. A refrigeration device, comprising a housing, an evaporator, a variable frequency compressor, an evaporator fan, a defrosting heating wire, a sensor, and a controller, characterized in that, The controller is configured to execute the operating mode sensing and switching control method for a refrigeration device as described in any one of claims 1-8.

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