A cold storage temperature field equalization control method and system

Abstract

The application discloses a cold storage temperature field equalization control method and system, and belongs to the technical field of cold chain logistics and automatic control, comprising the following steps: obtaining a running state step signal of a cold storage refrigerating unit, triggering a high-frequency sampling mode in response to the running state step signal, and obtaining transient temperature response time series data of multiple distributed monitoring points in the cold storage; extracting a second-order dynamic thermal feature based on the transient temperature response time series data, taking the second-order dynamic thermal feature as a flow field identification basis, constructing a thermal flow field space impedance topology model reflecting the airflow resistance distribution in the cold storage, and obtaining a space mapping relationship containing a low-resistance short-circuit region and a high-resistance thermal retention region; and determining a target airflow penetration strategy of each region according to the thermal flow field space impedance topology model. The application realizes high equalization control of the cold storage temperature field and maximization of energy utilization efficiency by constructing the thermal flow field space impedance topology model reflecting the airflow resistance distribution in the cold storage.

Description

Technical Field

[0001] This invention relates to the field of cold chain logistics and automated control technology, and in particular to a method and system for temperature field equalization control in cold storage. Background Technology

[0002] With the rapid development of the cold chain logistics industry, cold storage is the core link in the storage of perishable goods such as food and medicine. The uniformity of the internal temperature field directly determines the quality of goods and the safety of storage and transportation. In practical applications, cold storage is usually in a dynamic operating environment. Frequent entry and exit of goods, changes in stacking methods, and the start and stop of refrigeration units will all have a complex impact on the airflow organization inside the storage.

[0003] However, existing cold storage temperature control technologies still have the following significant defects and shortcomings when dealing with the above-mentioned complex operating conditions: Cold storage temperature monitoring systems usually adopt a fixed-frequency low-frequency sampling mode, which has serious lag. Due to the excessively large sampling interval, the transient temperature impact characteristics at the moment of airflow arrival are often lost, making it impossible for the control system to make targeted adjustments; For local hot spots, simply increasing the speed of the air cooler in an attempt to increase the air volume to blow through the shelves is not feasible in high-resistance areas where goods are densely stacked. Simply increasing the wind speed not only makes it difficult for the airflow to penetrate deep into the shelves, but also significantly increases energy consumption, resulting in the greater the wind, the greater the resistance, and the more difficult it is to blow deep; Cold air tends to flow to the path of least resistance, forming an ineffective circulation of low-resistance airflow short-circuit, resulting in wasted cooling capacity. Existing technologies mainly rely on the installation of physical canvas baffles or air deflectors, resulting in high installation costs. Moreover, once installed and fixed, they cannot adapt to the dynamic changes in the stacking position of goods, lacking flexibility.

[0004] In summary, there is an urgent need for a method and system for controlling the temperature field balance in cold storage that can accurately identify the flow field resistance distribution and achieve on-demand distribution and active reconfiguration of airflow without the need for physical consumables. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a method and system for temperature field equilibrium control in cold storage.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a method and system for equalizing the temperature field in a cold storage facility, the method comprising the following steps:

[0007] The operating status step signal of the cold storage refrigeration unit is acquired, and a high-frequency sampling mode is triggered in response to the operating status step signal to obtain transient temperature response time series data of multiple distributed monitoring points inside the cold storage.

[0008] Based on the transient temperature response time series data, second-order dynamic thermal features are extracted. Using the second-order dynamic thermal features as the basis for flow field identification, a thermal flow field spatial impedance topology model reflecting the airflow resistance distribution inside the cold storage is constructed to obtain a spatial mapping relationship including low-resistance short-circuit region and high-resistance heat retention region.

[0009] Based on the aforementioned thermal flow field spatial impedance topology model, the target airflow penetration strategy for each region is determined, and based on the target airflow penetration strategy, differentiated frequency modulation control is performed on the variable frequency fan in the corresponding region to generate a flow field regulation command sequence.

[0010] The flow field control command sequence is executed with closed-loop feedback, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

[0011] In a preferred embodiment of the present invention, the step of acquiring the operating state step signal of the cold storage refrigeration unit and triggering a high-frequency sampling mode in response to the operating state step signal to obtain transient temperature response time-series data of multiple distributed monitoring points inside the cold storage includes:

[0012] The main control signals of the cold storage refrigeration unit are monitored in real time. When a compressor start signal, a fan full-speed switching signal, or a defrosting end signal is detected, the current moment is locked as the step trigger moment.

[0013] Within a preset transient capture time window after the step trigger moment, the sampling frequency of the distributed monitoring points is switched from the steady-state monitoring frequency to the transient capture frequency, wherein the transient capture frequency is at least ten times the steady-state monitoring frequency;

[0014] Collect continuous temperature change values ​​within the preset transient capture time window to generate transient temperature response time series data that corresponds one-to-one with the spatial location of each of the distributed monitoring points.

[0015] In a preferred embodiment of the present invention, the step of extracting second-order dynamic thermal features based on the transient temperature response time-series data, and using the second-order dynamic thermal features as the basis for flow field identification to construct a thermal flow field spatial impedance topology model reflecting the airflow resistance distribution inside the cold storage, includes:

[0016] Perform second-order differential operations on the transient temperature response time series data to calculate the initial acceleration value and response lag time value of the temperature drop;

[0017] The initial acceleration value is combined with the response lag time value to generate the second-order dynamic thermal characteristic describing the airflow arrival capability at each of the distributed monitoring points.

[0018] Based on the preset flow resistance mapping rules, regions exhibiting high acceleration values ​​and low lag time values ​​are mapped to the low-resistance short-circuit regions, and regions exhibiting low acceleration values ​​and high lag time values ​​are mapped to the high-resistance heat retention regions, thereby generating the thermal flow field spatial impedance topology model.

[0019] In a preferred embodiment of the present invention, the step of performing differentiated frequency modulation control on the variable frequency fan in the corresponding region according to the target airflow penetration strategy to generate a flow field regulation command sequence includes:

[0020] In response to the target region being identified as the low-resistance short-circuit region in the thermal flow field spatial impedance topology model, an aerodynamic flow resistance gain adjustment command is generated. The aerodynamic flow resistance gain adjustment command is used to drive the corresponding fan to reduce its speed or drive the adjacent fan to form opposing airflow to construct a virtual high-pressure wind barrier.

[0021] In response to the target region being identified as the high-resistance heat retention region in the thermal flow field spatial impedance topology model, a frequency sweep optimization command is generated. The frequency sweep optimization command is used to drive the corresponding fan to perform sinusoidal speed fluctuations within a preset frequency band to conduct airflow penetration tests.

[0022] In a preferred embodiment of the present invention, the step of performing frequency conversion sweep optimization and resonance locking on the high thermal resistance retention region to generate a balanced cold storage temperature field distribution includes:

[0023] During the execution of the frequency sweep optimization command, the operating frequency of the variable frequency fan is linearly increased from the minimum preset frequency to the maximum preset frequency.

[0024] The temperature drop rate at the monitoring point deep within the high thermal resistance retention area is calculated in real time, and the response curve of the temperature drop rate as a function of the operating frequency is monitored.

[0025] Determine the fan operating frequency corresponding to the peak temperature drop rate in the response curve, and mark this frequency as the optimal resonant transmission frequency;

[0026] The variable frequency fan is controlled to operate at the optimal resonant penetration frequency, generating a continuous pulsating airflow to eliminate heat accumulation in the high-resistance heat retention area through the pulsating exchange of hot and cold air.

[0027] In a preferred embodiment of the present invention, the aerodynamic flow resistance gain adjustment for the low-resistance short-circuit region includes:

[0028] Identify the first and second frequency converter fans located on both sides of the low-resistance short-circuit region;

[0029] The first and second variable frequency fans are controlled to operate at the same frequency, and their speed ratio and air delivery angle are adjusted so that the two airflows collide at the center of the low-resistance short-circuit region.

[0030] By utilizing the local high static pressure zone generated by airflow collision to form an aerodynamic barrier layer, cold air is forced to flow to the adjacent high heat resistance retention area, thereby achieving passive reconstruction of the flow field.

[0031] A cold storage temperature field equalization control system includes:

[0032] The transient sensing module is configured to acquire the step signal of the operating status of the cold storage refrigeration unit, and trigger a high-frequency sampling mode in response to the step signal of the operating status to obtain the transient temperature response time series data of multiple distributed monitoring points inside the cold storage.

[0033] The topology reconstruction module is configured to extract second-order dynamic thermal features based on the transient temperature response time-series data, and use the second-order dynamic thermal features as the basis for flow field identification to construct a thermal flow field spatial impedance topology model that reflects the airflow resistance distribution inside the cold storage, thereby obtaining a spatial mapping relationship that includes low-resistance short-circuit regions and high-resistance thermal stagnation regions.

[0034] The strategy generation module is configured to determine the target airflow penetration strategy for each region based on the thermal flow field spatial impedance topology model, and to perform differentiated frequency modulation control on the variable frequency fan in the corresponding region based on the target airflow penetration strategy, thereby generating a flow field regulation command sequence.

[0035] The closed-loop execution module is configured to perform closed-loop feedback execution on the flow field control command sequence, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

[0036] In a preferred embodiment of the present invention, the transient sensing module includes:

[0037] The unit status synchronization interface unit is used to capture hard-wired signals of compressor start-up / stop and defrost solenoid valve operation in real time.

[0038] A distributed low-heat inertial sensor array is deployed at the return air vents, walls, and deep within shelves of the cold storage facility to collect temperature signals.

[0039] In a preferred embodiment of the present invention, the topology reconstruction module includes:

[0040] The feature extraction calculation unit is used to perform second derivative operations on the transient temperature response time-series data;

[0041] The spatial mapping logic unit stores the flow resistance determination threshold, which is used to compare the calculated acceleration value with the lag time value, and automatically marks the boundary between the low-resistance short-circuit region and the high-resistance heat retention region in the thermal flow field spatial impedance topology model.

[0042] In a preferred embodiment of the present invention, the closed-loop execution module includes:

[0043] A sweep frequency signal generator is used to output a drive waveform whose frequency changes linearly with time to the variable frequency fan.

[0044] The resonant peak lock controller is used to analyze the temperature drop feedback during the frequency sweep process in real time. When the extreme point of the temperature drop rate is detected, it automatically locks the current output frequency and maintains the output at that frequency until the next control cycle is triggered.

[0045] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0046] (1) This invention constructs a thermal flow field spatial impedance topology model that reflects the airflow resistance distribution inside the cold storage, thereby achieving accurate identification of low-resistance short-circuit regions and high-resistance heat retention regions, and performs differentiated frequency modulation control accordingly. By combining aerodynamic flow resistance gain adjustment and frequency sweep optimization technology, the on-demand distribution and active reconstruction of airflow are achieved, fundamentally solving the technical problem of airflow short-circuiting and heat accumulation caused by the dynamic entry and exit of goods inside the cold storage. By eliminating ineffective air supply and enhancing deep penetration, the high-balance control of the temperature field of the cold storage and the maximization of energy utilization efficiency are achieved.

[0047] (2) This invention triggers a high-frequency sampling mode in response to a step signal in the operating state, and extracts second-order dynamic thermal features containing initial acceleration values ​​and response lag time values ​​based on the acquired transient temperature response time series data. This is used as the basis for flow field identification to construct a thermal flow field spatial impedance topology model, which effectively decouples the relationship between spatial distance and airflow resistance, and accurately identifies the root cause of uneven temperature, namely low-resistance short circuit and high-resistance thermal stagnation. Compared with the monitoring method of fixed low-frequency sampling at the minute level in the prior art, which causes the airflow arrival time to be blurred and the transient temperature impact characteristics to be lost due to the large sampling interval, it is impossible to distinguish whether the temperature abnormality is caused by the distance or the obstruction of goods. This invention effectively solves the above-mentioned defects of flow field identification failure caused by insufficient sampling frequency, significantly improves the physical resolution of flow field identification, and elevates the cold storage control from passive temperature response to active flow field management.

[0048] (3) Based on the spatial impedance topology model of the thermal flow field, this invention uses adjacent fans to form opposing airflows in the low-resistance short-circuit area to construct a virtual high-pressure wind barrier. In the high-resistance heat retention area, the variable frequency fan is driven to perform frequency sweep optimization and lock the optimal resonance penetration frequency. The local high static pressure area generated by the airflow collision cuts off the short-circuit path, forcing the cold air to flow to the adjacent area, destroying the boundary layer deep in the shelf to eliminate heat accumulation. Compared with the existing technology, which simply increases the fan speed to try to blow through the shelf, it is difficult to achieve the effect because the flow resistance increases with the square of the flow velocity, or the use of physical canvas baffles leads to high installation costs and cannot adapt to changes in cargo stacking. This invention achieves intelligent redistribution and passive reconstruction of the flow field without the need for physical consumables and with zero marginal cost. It achieves the maximum airflow penetration depth with the minimum energy consumption, significantly eliminates local hot spots, and achieves energy saving and consumption reduction while improving the freezing quality.

[0049] (4) Through the collaborative work of the transient sensing module, topology reconstruction module, strategy generation module and closed-loop execution module, the present invention forms a complete closed-loop control system from flow field development to active intervention. The system uses the real-time calculated temperature drop rate as a feedback signal to dynamically correct the output parameters of the variable frequency fan until the deviation converges, ensuring that the control strategy adapts to the dynamic changes of cold storage goods in real time. Through targeted aerodynamic flow resistance gain adjustment and resonance locking, the present invention avoids the ineffective circulation of cold energy caused by airflow short circuit and breaks through the flow resistance bottleneck of deep shelves, thereby realizing the temperature field balance in the entire space of the cold storage, significantly improving the effective volume utilization rate of the cold storage, and has significant economic value and engineering application prospects. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a flowchart illustrating the control method of the present invention;

[0052] Figure 2 This is a flowchart illustrating the steps of the control method of the present invention;

[0053] Figure 3 This is a structural block diagram of a preferred embodiment of the system of the present invention; Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0056] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0057] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] In one embodiment, such as Figure 1 and Figure 2 As shown, a method for temperature field equalization control in cold storage is provided to address the problem that static control strategies cannot handle the flow field changes caused by the dynamic entry and exit of goods in cold storage. The method includes the following steps:

[0059] The operating status step signal of the cold storage refrigeration unit is acquired, and a high-frequency sampling mode is triggered in response to the operating status step signal to obtain transient temperature response time series data of multiple distributed monitoring points inside the cold storage.

[0060] Based on the transient temperature response time series data, second-order dynamic thermal features are extracted. Using the second-order dynamic thermal features as the basis for flow field identification, a thermal flow field spatial impedance topology model reflecting the airflow resistance distribution inside the cold storage is constructed to obtain a spatial mapping relationship including low-resistance short-circuit region and high-resistance heat retention region.

[0061] Based on the aforementioned thermal flow field spatial impedance topology model, the target airflow penetration strategy for each region is determined, and based on the target airflow penetration strategy, differentiated frequency modulation control is performed on the variable frequency fan in the corresponding region to generate a flow field regulation command sequence.

[0062] The flow field control command sequence is executed with closed-loop feedback, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

[0063] In one embodiment, step S201 involves acquiring the operating status step signal of the cold storage refrigeration unit and triggering a high-frequency sampling mode in response to the operating status step signal to obtain transient temperature response time-series data from multiple distributed monitoring points inside the cold storage.

[0064] Among them, the step signal of operating status specifically refers to the moment signal when the energy of the cold storage thermal system changes abruptly. For example, when the compressor switches from the shutdown state to the operating state, the temperature of the evaporator coil will drop sharply within tens of seconds, and the temperature of the air blown out by the evaporator will change abruptly. Or when defrosting ends and the fan restarts, the strong cold air will push the cold air into the depths of the cold storage like a wave. The above-mentioned energy change is the best probe for detecting the characteristics of the flow field. The distributed monitoring points cover the return air vent area, the direct blowing area of ​​the evaporator, the densely shelved area, and the dead corner area in space. The transient temperature response time series data refers to a set of raw temperature values ​​that are arranged in chronological order and have not been smoothed within a specific time period, which can completely record the waveform characteristics of temperature changes over time.

[0065] Preferably, step S201 specifically includes the following sub-steps:

[0066] The main control signals of the cold storage refrigeration unit are monitored in real time. When a compressor start signal, a fan full-speed switching signal, or a defrosting end signal is detected, the current moment is locked as the step trigger moment.

[0067] Within a preset transient capture time window after the step trigger moment, the sampling frequency of the distributed monitoring points is switched from the steady-state monitoring frequency to the transient capture frequency, wherein the transient capture frequency is at least ten times the steady-state monitoring frequency;

[0068] Collect continuous temperature change values ​​within the preset transient capture time window to generate transient temperature response time series data that corresponds one-to-one with the spatial location of each of the distributed monitoring points.

[0069] Specifically, the current moment is locked as the step trigger moment, which is obtained in the following way: the level state of the main control signal is scanned, and in response to the detection of a rising edge from low to high or a falling edge from high to low of the main control signal level, the high-precision real-time clock of the system is read, and the moment when the edge transition occurs is marked as the time zero point, which serves as the alignment reference for subsequent timing data.

[0070] Preferably, the preset transient capture time window can be obtained by: acquiring the longest diagonal physical distance of the cold storage. and the minimum design wind speed of the evaporative cooler Calculate the theoretical maximum air circulation time The preset transient capture time window is set as follows: ,in The safety redundancy factor ranges from 1.5 to 3.0 to ensure that the window duration covers the physical transmission time required for the airflow to travel from the air outlet to the farthest monitoring point inside the storage room. The steady-state monitoring frequency is typically set to 0.01Hz to 0.1Hz, i.e., sampling once every 10 to 100 seconds, to monitor the slow drift of the storage room temperature. The transient capture frequency is typically set to 1Hz to 10Hz, i.e., sampling 1 to 10 times per second, to meet the sampling theorem requirements for details of airflow turbulence and rapid temperature fluctuations.

[0071] Specifically, transient temperature response time-series data corresponding one-to-one with the spatial location of each of the distributed monitoring points is generated. A multi-dimensional data matrix can be constructed. Using the unique hardware identifier (ID) of each distributed monitoring point and the pre-stored three-dimensional spatial coordinates (x, y, z) as indexes, N consecutive temperature sampling values ​​collected within the preset transient capture time window are filled into the matrix sequence in timestamp order. The time phase deviation between each sensor is eliminated through a time synchronization protocol, and the final output format is as follows. Structured time-series datasets.

[0072] It is worth noting that in this embodiment, a high-frequency sampling mode is triggered in response to a step signal in the operating state, and a preset transient capture time window is calculated based on the physical transmission time. This enables the recording of the dynamic response characteristics of the cold storage thermal system. Compared with the monitoring method using fixed low-frequency sampling in the prior art, this embodiment effectively solves the technical defects of blurred airflow arrival time and loss of transient temperature impact characteristics caused by excessively large sampling intervals. This method can accurately capture the microsecond-level temperature fluctuation details caused by airflow at different spatial locations, providing a high-fidelity data foundation for subsequent extraction of second-order dynamic thermal features and identification of low-resistance short-circuit and high-resistance heat retention areas. This significantly improves the physical resolution of flow field identification and the accuracy of control strategies.

[0073] In one embodiment, step S202 involves extracting second-order dynamic thermal features based on the transient temperature response time-series data, using the second-order dynamic thermal features as the basis for flow field identification, constructing a thermal flow field spatial impedance topology model that reflects the airflow resistance distribution inside the cold storage, and obtaining a spatial mapping relationship that includes low-resistance short-circuit regions and high-resistance thermal stagnation regions.

[0074] Preferably, step S202 specifically includes the following sub-steps:

[0075] Perform second-order differential operations on the transient temperature response time series data to calculate the initial acceleration value and response lag time value of the temperature drop;

[0076] The initial acceleration value is combined with the response lag time value to generate the second-order dynamic thermal characteristic describing the airflow arrival capability at each of the distributed monitoring points.

[0077] Based on the preset flow resistance mapping rules, regions exhibiting high acceleration values ​​and low lag time values ​​are mapped to the low-resistance short-circuit regions, and regions exhibiting low acceleration values ​​and high lag time values ​​are mapped to the high-resistance heat retention regions, thereby generating the thermal flow field spatial impedance topology model.

[0078] Among them, the second-order dynamic thermal characteristic refers to the vector characteristic that comprehensively describes the acceleration of temperature change and the time response delay. This vector characteristic physically represents the aerodynamic penetration force and transmission path resistance of cold air flow from the outlet of the air cooler to the monitoring point. The thermal flow field spatial impedance topology model refers to a digital three-dimensional field model that maps the geometric coordinates of physical space to the value of airflow resistance. This thermal flow field spatial impedance topology model divides the cold storage space into a low-impedance zone where airflow can easily pass through and a high-impedance zone where airflow cannot reach.

[0079] Specifically, the initial acceleration value of the temperature drop is calculated, and a second-order central difference operation is performed on the discrete transient temperature response time-series data, with the sampling time interval set to [value missing]. ,time Temperature value The formula for calculating the rate of temperature drop is:

[0080] ,

[0081] The formula for calculating temperature drop acceleration is:

[0082] ;

[0083] The negative extreme value of the temperature drop acceleration within a preset time period after the step trigger is selected as the initial acceleration value, i.e. the maximum deceleration rate or the average acceleration during the initial change phase. The larger the absolute value of the initial acceleration value, the more violent the airflow impact.

[0084] Specifically, the response lag time is calculated by setting an effective temperature change threshold, with the step trigger time as the trigger point. Starting from the threshold, retrieve the moment in the transient temperature response time series data when the temperature change threshold is first exceeded. The formula for calculating the time difference is:

[0085] ,

[0086] The time difference The response lag time value is determined to be the value that characterizes the pure lag in airflow transmission.

[0087] Specifically, the second-order dynamic thermal features are generated by constructing feature vectors. Where i is the monitoring point number; to eliminate the influence of dimensions, it is preferred to perform monitoring on all monitoring points. and Maximum and minimum value normalization is performed to generate standardized dimensionless feature vectors, which serve as the input for subsequent flow field identification algorithms.

[0088] Specifically, areas exhibiting high acceleration and low lag time are mapped as low-resistance short-circuit areas. These areas are typically located near return air vents or along the direct path of the evaporator, where cold air returns without sufficient heat exchange, resulting in energy waste—a phenomenon commonly known as air short-circuiting. Areas exhibiting low acceleration and high lag time are mapped as high-resistance heat retention areas. These areas are typically located in densely packed shelving areas, corners, or at the end of the evaporator's range, where airflow struggles to penetrate, leading to heat accumulation and becoming the primary areas causing goods spoilage.

[0089] Furthermore, the thermal flow field spatial impedance topology model is not a static image, but a dynamically updated data matrix. The system associates the spatial coordinates of each monitoring point with its corresponding flow resistance level to construct a three-dimensional impedance field, enabling the control system to identify airflow blockages and leaks.

[0090] It is worth noting that this embodiment employs a second-order feature extraction and impedance modeling method based on transient response to visualize the invisible airflow field inside the cold storage. Compared with the shortcomings of existing technologies that rely solely on steady-state temperature values ​​for feedback control (i.e., unable to distinguish whether high temperature is due to distance or airflow obstruction by goods), this embodiment effectively decouples the relationship between spatial distance and airflow resistance by introducing dynamic indicators of acceleration and lag time. This allows for precise identification of the root causes of temperature unevenness, namely low-resistance short circuits and high-resistance stagnation, providing a reliable decision-making basis for subsequent precise control. This elevates cold storage control from a passive temperature response to an active flow field management level, significantly optimizing the temperature uniformity and energy utilization efficiency of the cold storage.

[0091] In one embodiment, step S203: determine the target airflow penetration strategy for each region based on the thermal flow field spatial impedance topology model, and perform differentiated frequency modulation control on the variable frequency fan in the corresponding region based on the target airflow penetration strategy to generate a flow field regulation command sequence.

[0092] The target airflow penetration strategy is based on the impedance matching principle in fluid mechanics. In the complex flow field of a cold storage, cold air always tends to flow towards the path of least resistance, rather than the path that needs the most cooling. Therefore, the core of this strategy is to artificially increase the flow resistance of the short-circuit path while reducing or resonating the flow resistance of the heat retention path. The differentiated frequency modulation control refers to breaking the traditional control mode of unified frequency and simultaneous start-stop of cold storage fan groups, and instead implementing independent, refined vector control with different frequencies and phases for each or each group of variable frequency fans.

[0093] Preferably, step S203 includes:

[0094] In response to the target region being identified as the low-resistance short-circuit region in the thermal flow field spatial impedance topology model, an aerodynamic flow resistance gain adjustment command is generated. The aerodynamic flow resistance gain adjustment command is used to drive the corresponding fan to reduce its speed or drive the adjacent fan to form opposing airflow to construct a virtual high-pressure wind barrier.

[0095] In response to the target region being identified as the high-resistance heat retention region in the thermal flow field spatial impedance topology model, a frequency sweep optimization command is generated. The frequency sweep optimization command is used to drive the corresponding fan to perform sinusoidal speed fluctuations within a preset frequency band to conduct airflow penetration tests.

[0096] Among them, the aerodynamic flow resistance gain adjustment command refers to a control signal designed to increase the airflow resistance in a specific spatial area, which includes the target fan ID, target speed value, and phase synchronization parameters; the virtual high-pressure wind barrier refers to an invisible aerodynamic wall constructed using aerodynamic principles.

[0097] Specifically, a virtual high-pressure wind barrier is constructed. The system identifies adjacent fans located on both sides of the low-resistance short-circuit region and controls the two fans to output airflow in opposite directions with equal dynamic pressure. When the two airflows collide inelasticly at the center point of the short-circuit path, kinetic energy is converted into potential energy, forming a local high-pressure zone in the collision area with a static pressure significantly higher than the surrounding environment. Since the fluid naturally flows from high pressure to low pressure, this local high-pressure zone constitutes a physical flow resistance barrier, forcing the subsequent cold air to change its streamline trajectory and bypass the short-circuit region to flow into a deeper region with relatively low pressure due to thermal stagnation.

[0098] The frequency conversion sweep optimization command refers to a drive signal carrying dynamic frequency modulation parameters, indicating that the voltage frequency output by the frequency converter is no longer a constant value, but a waveform that varies with time. Preferably, the preset frequency band is usually set to 30Hz to 60Hz, covering most of the airflow resonance frequency points that may exist in the gaps between stacked goods.

[0099] Specifically, the sinusoidal speed fluctuation is obtained by superimposing a low-frequency modulation signal onto the wind turbine's fundamental carrier frequency to generate a driving function. The formula for calculating the driving function is as follows:

[0100] ,

[0101] in, This refers to the real-time target operating frequency output by the control system to the variable frequency fan at time t. This value is a variable that changes continuously with time and directly determines the instantaneous speed of the fan at that millisecond. This refers to the center frequency or average frequency of the fan's operation, representing the fan's basic airflow output level. This refers to the maximum deviation of the wind turbine's operating frequency from the reference frequency. The scan rate is t; t represents the current control cycle time. The corresponding fan is driven to run according to the drive function, thereby generating a pulsating airflow field. The constantly changing pulsating frequency is used to excite the air column resonance in the shelf gap, so as to test and find the optimal frequency point that can maximize the airflow penetration depth.

[0102] It is worth noting that this embodiment adopts a target airflow penetration strategy based on impedance matching. Compared with the existing technology that controls the overall start-up and shutdown or uniform speed adjustment of the fan based solely on the return air temperature, the existing technology cannot change the airflow distribution ratio, resulting in the inherent defects of excessively cold return air vents and excessively hot deep air vents. This embodiment effectively curbs the ineffective short-circuit circulation of cold energy by constructing a virtual high-pressure wind barrier for low-resistance short-circuit areas. At the same time, by performing frequency sweep optimization for high-resistance heat retention areas, the flow resistance bottleneck of deep shelves is overcome by utilizing the resonance principle. This method not only significantly improves the uniformity of the overall temperature field of the cold storage, but also greatly reduces the operating energy consumption of the refrigeration system by reducing ineffective air supply.

[0103] In one embodiment, step S204 involves executing closed-loop feedback on the flow field control command sequence, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

[0104] Preferably, step S204 includes:

[0105] During the execution of the frequency sweep optimization command, the operating frequency of the variable frequency fan is linearly increased from the minimum preset frequency to the maximum preset frequency.

[0106] The temperature drop rate at the monitoring point deep within the high thermal resistance retention area is calculated in real time, and the response curve of the temperature drop rate as a function of the operating frequency is monitored.

[0107] Determine the fan operating frequency corresponding to the peak temperature drop rate in the response curve, and mark this frequency as the optimal resonant transmission frequency;

[0108] The variable frequency fan is controlled to operate at the optimal resonant penetration frequency, generating a continuous pulsating airflow to eliminate heat accumulation in the high-resistance heat retention area through the pulsating exchange of hot and cold air.

[0109] Among them, closed-loop feedback execution refers to a real-time dynamic control process in which the system continuously collects the temperature status of the distributed monitoring points as feedback signals, calculates the deviation between the current state and the target state expected by the flow field control command, and then dynamically corrects the output parameters of the variable frequency fan until the deviation converges within a preset range; hot and cold air exchange through pulsation refers to the physical phenomenon of using pulsating airflow to excite the air column inside the porous medium to produce a large-amplitude oscillation displacement, which can enhance the mass exchange between deep stagnant air and external cold air.

[0110] Specifically, the drive operating frequency increases linearly, which is achieved by sending a frequency control signal to the frequency converter. The frequency control signal follows a linear frequency modulation function:

[0111] ,

[0112] in Minimum preset frequency, The sweep slope, The sweep duration is defined as the frequency sweep duration. This process generates an excitation source whose frequency slides continuously over time, designed to cover the range of fluid resonant frequencies that may exist in the gaps between cargo stacks.

[0113] Specifically, the rate of temperature decrease is calculated using temperature data collected from the deep monitoring points. Perform the sliding window differentiation operation, the formula is:

[0114] ,

[0115] in, It is the instantaneous temperature drop rate, which refers to how fast the temperature of the target monitoring point changes at time t. During the frequency conversion and frequency sweeping process, the larger this value is, the more effectively the current driving frequency can deliver the cooling energy to the monitoring point, that is, the airflow cooling work efficiency is the highest at this frequency. , which represents the derivative with respect to time t, used to extract the instantaneous trend of temperature change, that is, to calculate the ratio of the numerical difference between two adjacent sampling times to the time difference; Indicates that the window width is A simple moving average filter is used to remove measurement noise, ensuring that the obtained rate value reflects the true cooling trend. However, the raw signals collected by distributed monitoring points deployed in the field often contain superimposed electromagnetic interference or random high-frequency noise caused by airflow turbulence. Directly differentiating the raw data would significantly amplify the noise, causing the calculated rate curve to fluctuate wildly and making it impossible to identify the true resonance peak. Therefore, it is necessary to first... The operator smooths the original data.

[0116] Specifically, the response curve is monitored and obtained by constructing a real-time mapping table, based on the current instantaneous operating frequency. The x-axis represents the calculated rate of temperature decrease. Plot the frequency and efficiency response curves on the vertical axis. These curves visually reflect the efficiency of different fan frequencies in removing deep heat.

[0117] Specifically, the optimal resonance transmission frequency is determined by performing an extreme value search algorithm on the generated response curve to identify the global maximum point of the frequency and performance response curves. To prevent local noise interference, the second derivative criterion is preferably used, that is, confirming that the first derivative is zero and the second derivative is less than zero at this point, and locking the abscissa corresponding to this point as the optimal resonance transmission frequency.

[0118] Among them, pulsating airflow refers to unsteady airflow in which wind pressure and velocity fluctuate periodically at a specific frequency; eliminating heat accumulation refers to using resonant energy to destroy the boundary layer deep inside the shelf, forcing the trapped hot air to flow out.

[0119] Specifically, the locked operation is achieved by setting the inverter's output frequency to the optimal resonant penetration frequency determined in the previous step, and by superimposing a small disturbance signal to maintain the stability of the resonant state.

[0120] It is worth noting that this embodiment employs a closed-loop control method based on frequency conversion sweep optimization and resonance locking, solving the industry pain point of difficulty in cooling deep goods in cold storage. Compared with the crude method in existing technologies that simply try to blow air through the shelves by increasing the fan speed, existing technologies often lead to the physical paradox of the greater the airflow, the greater the resistance, and the more difficult it is to blow into the depths due to the square-law increase in flow resistance with the flow velocity. This embodiment utilizes the principle of resonance to find the natural frequency of the gap between the shelves for airflow, achieving the maximum airflow penetration depth with minimal energy consumption. By stimulating the exchange of hot and cold air through pulses, the system can efficiently extract the hot air trapped deep inside, significantly eliminating local hot spots and achieving energy saving and consumption reduction while improving freezing quality.

[0121] Preferably, step S204 further includes:

[0122] Identify the first and second frequency converter fans located on both sides of the low-resistance short-circuit region;

[0123] The first and second variable frequency fans are controlled to operate at the same frequency, and their speed ratio and air delivery angle are adjusted so that the two airflows collide at the center of the low-resistance short-circuit region.

[0124] By utilizing the local high static pressure zone generated by airflow collision to form an aerodynamic barrier layer, cold air is forced to flow to the adjacent high heat resistance retention area, thereby achieving passive reconstruction of the flow field.

[0125] The first variable frequency fan and the second variable frequency fan refer to specific fan units that are physically distributed on opposite sides of the low-resistance short-circuit area and whose outlet airflow vectors can cover the area.

[0126] Specifically, the fan pairs are identified by extracting the spatial geometric center coordinates of the low-resistance short-circuit region based on the aforementioned thermal flow field spatial impedance topology model. By iterating through the installation coordinates of all variable frequency fans in the cold storage and the preset outlet jet cone model, two fans were selected. and The condition is that the central axis of its jet cone lies in... Nearby spatial intersection angle The distances between the two wind turbines reaching the center point are greater than the preset threshold, and the distance difference between them is less than the preset effective range threshold; the selected turbines will be... Marked as the first variable frequency fan, It is marked as the second variable frequency fan.

[0127] Among them, the same frequency refers to the synchronous speed modulation cycle of the two fans, such as the sinusoidal speed fluctuation at a frequency of 0.5Hz; adjusting the speed ratio and air delivery angle of the two fans refers to finely adjusting the arrival time deviation of the peak of the output pressure wave of the two fans on the time axis.

[0128] Specifically, adjusting the speed ratio and air delivery angle to achieve counter-collision is achieved by setting the drive function of the first variable frequency fan as follows:

[0129] ,

[0130] The drive function for the second variable frequency fan is:

[0131] ;

[0132] in, and , respectively refer to the real-time control quantities applied by the control system to the first and second variable frequency fans at time t; This refers to the base operating frequency or average speed maintained by both wind turbines. This parameter must be kept consistent in both wind turbines to ensure that the momentum flux of the two opposing airflows is equal on a macroscopic scale. If the reference values ​​are inconsistent, the stagnation point generated by the collision will deviate from the geometric center, causing the virtual wind barrier position to shift and failing to effectively block the short-circuit path. The amplitude of the sinusoidal fluctuation superimposed on the reference value determines the intensity of the airflow pulse. A larger amplitude value means that the fan will produce a more intense push-pull effect, which helps to generate a higher peak static pressure at the collision center, thereby building a more robust aerodynamic barrier layer. The angular velocity refers to the control fluctuation, and t refers to the unified high-precision timestamp of the system, ensuring that the two physically separated wind turbines achieve microsecond-level synchronization in control. This refers to the time offset of the second variable frequency fan relative to the first variable frequency fan in terms of the fluctuation period. Because there may be slight differences in the physical distance between the two fans and the offset center point, or deviations in the inertial response of the fans themselves, direct synchronous driving may cause the pressure peaks of the two airflows to not reach the center point simultaneously. This can be addressed through fine-tuning. It can compensate for differences in transmission delay, when When adjusted to the optimal value, the pressure peaks of the two airflows will coincide at the target coordinate point, making the vector sum of the airflow velocity at that point zero, while the static pressure potential energy reaches its maximum value, thus forming the most effective aerodynamic blocking effect.

[0133] The system monitors the wind speed at the center monitoring point of the low-resistance short-circuit area in real time and dynamically adjusts the rotation speed ratio and air delivery angle parameters using an extreme value search algorithm. When the wind speed at the center monitoring point drops to its minimum and the static pressure rises to its maximum, it determines that the momentum of the two airflows reaches a balance and cancels each other out at this point, and locks the current rotation speed ratio and air delivery angle, thereby ensuring that the stagnation point generated by the collision is accurately located at the center of the area.

[0134] Among them, the aerodynamic barrier layer refers to the high-pressure air band formed by the conversion of fluid kinetic energy into pressure potential energy, which acts as a blocking effect similar to a physical guide vane in the flow field; passive reconfiguration refers to forcing the airflow to change its path by altering the pressure field distribution without changing the physical structure of the cold storage. Specifically, the physical mechanism of forming the aerodynamic barrier layer is as follows: according to Bernoulli's principle, when two high-speed airflows collide and the flow velocity approaches 0, the dynamic pressure in this area is converted into static pressure, forming a pressure ridge that is significantly higher than the surrounding environment pressure. Since fluid always flows from the high-pressure area to the low-pressure area, this pressure ridge naturally cuts off the low-resistance short-circuit path that originally flowed to the return air vent. It uses the pressure difference to drive the cold air to turn to the adjacent area with relatively high flow resistance but low pressure, that is, the high-resistance heat retention area, thereby achieving intelligent redistribution of the flow field without the need for physical consumables.

[0135] It is worth noting that this embodiment employs a virtual windbreak construction technology based on dual-fan counter-phase control, effectively solving the problems of excessive cooling at the return air vent and energy waste caused by airflow short-circuiting in cold storage. Compared with existing technologies that typically use physical canvas baffles or deflectors to solve the short-circuiting problem, existing technologies suffer from high installation costs and inability to adapt to changes in cargo stacking once installed. This embodiment has extremely high flexibility and zero marginal cost advantages, and can dynamically adjust the position of the barrier according to the distribution of goods, demonstrating the intelligent and adaptive benefits of flow field control, and significantly improving the effective volume utilization rate and temperature uniformity of cold storage.

[0136] In one embodiment, such as Figure 3 As shown, a cold storage temperature field equalization control system is provided, including:

[0137] The transient sensing module is configured to acquire the step signal of the operating status of the cold storage refrigeration unit, and trigger a high-frequency sampling mode in response to the step signal of the operating status to obtain the transient temperature response time series data of multiple distributed monitoring points inside the cold storage.

[0138] Specifically, existing temperature monitoring technologies typically employ low-frequency sampling at the minute level. This sampling frequency can only reflect temperature drift under steady-state conditions and cannot capture the dynamic characteristics of airflow at the moment of arrival. In this embodiment, the transient sensing module achieves the capture of temperature fluctuation fingerprints through a hardware-level triggering mechanism.

[0139] The transient sensing module further includes, in hardware, the following:

[0140] The unit status synchronization interface unit is used to capture hard-wired signals of compressor start-up and shutdown and defrost solenoid valve operation in real time. Preferably, the interface unit adopts an opto-isolation design to block strong electrical interference and ensure that the time jitter of the captured operating status step signal is less than 10 milliseconds.

[0141] A distributed low-thermal inertia sensor array is deployed in the return air vents, walls, and deep within shelves of the cold storage to collect temperature signals. If a traditional high-thermal inertia sensor is used, its own thermal capacity will smooth out the transient temperature changes caused by airflow impact, leading to the failure of subsequent flow resistance identification. Therefore, this embodiment preferably uses an exposed thermistor or MEMS temperature sensor.

[0142] The topology reconstruction module is configured to extract second-order dynamic thermal features based on the transient temperature response time-series data, and use the second-order dynamic thermal features as the basis for flow field identification to construct a thermal flow field spatial impedance topology model that reflects the airflow resistance distribution inside the cold storage, thereby obtaining a spatial mapping relationship that includes low-resistance short-circuit regions and high-resistance thermal stagnation regions.

[0143] Furthermore, the topology reconstruction module includes:

[0144] The feature extraction calculation unit is used to perform second derivative operations on the transient temperature response time series data to extract physical quantities that can characterize the airflow impact force from the discrete temperature data.

[0145] The spatial mapping logic unit stores the flow resistance determination threshold, which is used to compare the calculated acceleration value with the lag time value, and automatically marks the boundary between the low-resistance short-circuit region and the high-resistance heat retention region in the thermal flow field spatial impedance topology model.

[0146] The strategy generation module is configured to determine the target airflow penetration strategy for each region based on the thermal flow field spatial impedance topology model, and to perform differentiated frequency modulation control on the variable frequency fan in the corresponding region based on the target airflow penetration strategy, thereby generating a flow field regulation command sequence.

[0147] The target airflow penetration strategy is not a uniform speed adjustment, but a differentiated strategy based on the impedance matching principle. For areas where airflow can easily pass through, it is necessary to increase resistance or reduce airflow; for areas where airflow is difficult to reach, it is necessary to enhance penetration through specific waveform excitation.

[0148] The closed-loop execution module is configured to perform closed-loop feedback execution on the flow field control command sequence, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

[0149] Furthermore, the closed-loop execution module includes:

[0150] A sweep frequency signal generator is used to output a drive waveform whose frequency changes linearly with time to the variable frequency fan, which is completely different from the constant voltage output by traditional PID control.

[0151] The resonant peak lock controller is used to analyze the temperature drop feedback during the frequency sweep process in real time. When the extreme point of the temperature drop rate is detected, it automatically locks the current output frequency and maintains the output at that frequency until the next control cycle is triggered.

[0152] In summary, the present invention proposes a method and system for equalizing the temperature field in a cold storage facility. By extracting transient thermal features to construct a flow resistance topology map and utilizing aerodynamic counter-current and frequency resonance technologies, it achieves a high degree of temperature field balance and optimal energy efficiency configuration in the cold storage facility without human intervention, demonstrating significant economic value and promising engineering applications.

[0153] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for temperature field equalization control in cold storage, characterized in that, The method includes the following steps: The operating status step signal of the cold storage refrigeration unit is acquired, and a high-frequency sampling mode is triggered in response to the operating status step signal to obtain transient temperature response time series data of multiple distributed monitoring points inside the cold storage. Based on the transient temperature response time series data, second-order dynamic thermal features are extracted. Using the second-order dynamic thermal features as the basis for flow field identification, a thermal flow field spatial impedance topology model reflecting the airflow resistance distribution inside the cold storage is constructed to obtain a spatial mapping relationship including low-resistance short-circuit region and high-resistance heat retention region. Based on the aforementioned thermal flow field spatial impedance topology model, the target airflow penetration strategy for each region is determined, and based on the target airflow penetration strategy, differentiated frequency modulation control is performed on the variable frequency fan in the corresponding region to generate a flow field regulation command sequence. The flow field control command sequence is executed with closed-loop feedback, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

2. The method for equalizing the temperature field in a cold storage facility according to claim 1, characterized in that, The step signal of the operating status of the cold storage refrigeration unit is acquired, and a high-frequency sampling mode is triggered in response to the step signal to obtain transient temperature response time-series data of multiple distributed monitoring points inside the cold storage, including: The main control signals of the cold storage refrigeration unit are monitored in real time. When a compressor start signal, a fan full-speed switching signal, or a defrosting end signal is detected, the current moment is locked as the step trigger moment. Within a preset transient capture time window after the step trigger moment, the sampling frequency of the distributed monitoring points is switched from the steady-state monitoring frequency to the transient capture frequency, wherein the transient capture frequency is at least ten times the steady-state monitoring frequency; Collect continuous temperature change values ​​within the preset transient capture time window to generate transient temperature response time series data that corresponds one-to-one with the spatial location of each of the distributed monitoring points.

3. The method for equalizing the temperature field in a cold storage facility according to claim 1, characterized in that, The process involves extracting second-order dynamic thermal features based on the transient temperature response time-series data, using these features as the basis for flow field identification, and constructing a thermal flow field spatial impedance topology model that reflects the airflow resistance distribution inside the cold storage, including: Perform second-order differential operations on the transient temperature response time series data to calculate the initial acceleration value and response lag time value of the temperature drop; The initial acceleration value is combined with the response lag time value to generate the second-order dynamic thermal characteristic describing the airflow arrival capability at each of the distributed monitoring points. Based on the preset flow resistance mapping rules, regions exhibiting high acceleration values ​​and low lag time values ​​are mapped to the low-resistance short-circuit regions, and regions exhibiting low acceleration values ​​and high lag time values ​​are mapped to the high-resistance heat retention regions, thereby generating the thermal flow field spatial impedance topology model.

4. The method for equalizing the temperature field in a cold storage facility according to claim 1, characterized in that, The step of performing differentiated frequency modulation control on the variable frequency fan in the corresponding area according to the target airflow penetration strategy, and generating a flow field regulation command sequence, includes: In response to the target region being identified as the low-resistance short-circuit region in the thermal flow field spatial impedance topology model, an aerodynamic flow resistance gain adjustment command is generated. The aerodynamic flow resistance gain adjustment command is used to drive the corresponding fan to reduce its speed or drive the adjacent fan to form opposing airflow to construct a virtual high-pressure wind barrier. In response to the target region being identified as the high-resistance heat retention region in the thermal flow field spatial impedance topology model, a frequency sweep optimization command is generated. The frequency sweep optimization command is used to drive the corresponding fan to perform sinusoidal speed fluctuations within a preset frequency band to conduct airflow penetration tests.

5. The method for equalizing the temperature field in a cold storage facility according to claim 4, characterized in that, The step of performing frequency conversion sweep optimization and resonance locking on the high thermal resistance retention area to generate a balanced cold storage temperature field distribution includes: During the execution of the frequency sweep optimization command, the operating frequency of the variable frequency fan is linearly increased from the minimum preset frequency to the maximum preset frequency. The temperature drop rate at the monitoring point deep within the high thermal resistance retention area is calculated in real time, and the response curve of the temperature drop rate as a function of the operating frequency is monitored. Determine the fan operating frequency corresponding to the peak temperature drop rate in the response curve, and mark this frequency as the optimal resonant transmission frequency; The variable frequency fan is controlled to operate at the optimal resonant penetration frequency, generating a continuous pulsating airflow to eliminate heat accumulation in the high-resistance heat retention area through the pulsating exchange of hot and cold air.

6. The method for equalizing the temperature field in a cold storage facility according to claim 4, characterized in that, The aerodynamic flow resistance gain adjustment for the low-resistance short-circuit region includes: Identify the first and second frequency converter fans located on both sides of the low-resistance short-circuit region; The first and second variable frequency fans are controlled to operate at the same frequency, and their speed ratio and air delivery angle are adjusted so that the two airflows collide at the center of the low-resistance short-circuit region. By utilizing the local high static pressure zone generated by airflow collision to form an aerodynamic barrier layer, cold air is forced to flow to the adjacent high heat resistance retention area, thereby achieving passive reconstruction of the flow field.

7. A temperature field equalization control system for cold storage, characterized in that, include: The transient sensing module is configured to acquire the step signal of the operating status of the cold storage refrigeration unit, and trigger a high-frequency sampling mode in response to the step signal of the operating status to obtain the transient temperature response time series data of multiple distributed monitoring points inside the cold storage. The topology reconstruction module is configured to extract second-order dynamic thermal features based on the transient temperature response time-series data, and use the second-order dynamic thermal features as the basis for flow field identification to construct a thermal flow field spatial impedance topology model that reflects the airflow resistance distribution inside the cold storage, thereby obtaining a spatial mapping relationship that includes low-resistance short-circuit regions and high-resistance thermal stagnation regions. The strategy generation module is configured to determine the target airflow penetration strategy for each region based on the thermal flow field spatial impedance topology model, and to perform differentiated frequency modulation control on the variable frequency fan in the corresponding region based on the target airflow penetration strategy, thereby generating a flow field regulation command sequence. The closed-loop execution module is configured to perform closed-loop feedback execution on the flow field control command sequence, wherein aerodynamic flow resistance gain adjustment is performed for the low-resistance short-circuit region, and frequency conversion sweep optimization and resonance locking are performed for the high-resistance heat retention region, so as to generate a balanced cold storage temperature field distribution.

8. A cold storage temperature field equalization control system according to claim 7, characterized in that, The transient sensing module includes: The unit status synchronization interface unit is used to capture hard-wired signals of compressor start-up / stop and defrost solenoid valve operation in real time. A distributed low-heat inertial sensor array is deployed at the return air vents, walls, and deep within shelves of the cold storage facility to collect temperature signals.

9. A cold storage temperature field equalization control system according to claim 7, characterized in that, The topology reconstruction module includes: The feature extraction calculation unit is used to perform second derivative operations on the transient temperature response time-series data; The spatial mapping logic unit stores the flow resistance determination threshold, which is used to compare the calculated acceleration value with the lag time value, and automatically marks the boundary between the low-resistance short-circuit region and the high-resistance heat retention region in the thermal flow field spatial impedance topology model.

10. A cold storage temperature field equalization control system according to claim 7, characterized in that, The closed-loop execution module includes: A sweep frequency signal generator is used to output a drive waveform whose frequency changes linearly with time to the variable frequency fan. The resonant peak lock controller is used to analyze the temperature drop feedback during the frequency sweep process in real time. When the extreme point of the temperature drop rate is detected, it automatically locks the current output frequency and maintains the output at that frequency until the next control cycle is triggered.

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