Air-to-water method and air-to-water generator based on thermoelectric refrigeration

Abstract

This invention relates to the field of air-to-water technology, specifically to an air-to-water method and air-to-water generator based on thermoelectric refrigeration. The method calculates the thermal resistance value using the instantaneous input power, cold-end temperature, and hot-end temperature of the thermoelectric module, and establishes a dynamically updated frost-free reference thermal resistance value to obtain the thermal resistance increment value. The dispersion of the thermal resistance value within the observation window is used to obtain signal fluctuation characteristic values, which are then combined with the thermal resistance increment value to generate a single-step frost blockage increment and accumulated over time to obtain a frost blockage state value. When the state value exceeds a threshold, actual frost is determined, and a defrosting operation is performed. This method requires no additional sensors, utilizing only its own electrical and thermodynamic parameters for soft measurement, enabling the differentiation between drying conditions and frost blockage, avoiding ineffective defrosting, and ensuring defrosting accuracy and continuous water production efficiency.

Description

Technical Field

[0001] This invention relates to the field of air-to-water technology, specifically to an air-to-water method and air-to-water generator based on thermoelectric refrigeration. Background Technology

[0002] Air-to-water generators utilize thermoelectric modules to cool fins, lowering the temperature of flowing air below the dew point to condense water. To ensure water production efficiency, the cold-end temperature must typically be kept low. Under low-temperature or low-humidity conditions, the dew point drops due to the decreased partial pressure of water vapor in the air, requiring the fin surface temperature to fall below the freezing point, making frost formation highly likely. Accumulated frost blocks the fin gaps, causing a sharp decrease in airflow and rendering the equipment unable to produce water. Failure to defrost in time will result in ineffective operation; excessive defrosting will interrupt the cooling process and reduce water production.

[0003] Existing defrosting control solutions mainly rely on monitoring the cold end temperature or setting a fixed defrosting cycle. However, in low-temperature and low-humidity environments, the fin temperature will naturally drop due to the reduction in the sensible heat load of the air. This is highly similar to the temperature drop caused by frost formation, which can easily lead to misjudgment or even ineffective defrosting. Summary of the Invention

[0004] To address the technical problem in related technologies that fail to distinguish between the natural increase in thermal resistance under low-temperature drying conditions and the increase in thermal resistance caused by frost blockage, leading to frequent or untimely defrosting, this invention provides an air-to-water method and air-to-water generator based on thermoelectric refrigeration. The specific technical solution adopted is as follows: This invention proposes a method for producing water from air based on thermoelectric refrigeration, the method comprising: The instantaneous input power, cold end temperature, and hot end temperature of the thermoelectric module are obtained, and the thermal resistance value of the thermoelectric module is calculated. Based on the historical data of the thermal resistance value in the time series, the frost-free reference thermal resistance value is determined, and the thermal resistance increment value is obtained. The signal fluctuation characteristic value is obtained based on the dispersion of the thermal resistance value within the observation window. The single-step frost blockage increment is obtained by combining the signal fluctuation characteristic value with the thermal resistance increment value. The single-step frost blockage increment is accumulated over time to obtain the frost blockage state value. When the frosting blockage value exceeds the preset blockage judgment threshold, frosting blockage is determined, and the thermoelectric module is controlled to perform defrosting operation.

[0005] Furthermore, the method for calculating the thermal resistance value includes: When the instantaneous input power is greater than the minimum effective power threshold, the thermal resistance value is calculated using the difference between the hot end temperature and the cold end temperature as the numerator and the instantaneous input power as the denominator.

[0006] Further, determining a frost-free reference thermal resistance value based on historical data over time includes: When the frosting blockage state value is zero, the frost-free reference thermal resistance value is dynamically updated based on historical thermal resistance data. When the frosting blockage state value is greater than zero, the frost-free reference thermal resistance value is locked, so that the frost-free reference thermal resistance value remains unchanged from the most recent value.

[0007] Furthermore, the method for obtaining the thermal resistance increment value includes: The difference between the thermal resistance value and the frost-free reference thermal resistance value is compared with a preset dead zone threshold. When the difference is less than the preset dead zone threshold, the thermal resistance increment is set to zero; otherwise, the difference is used as the thermal resistance increment.

[0008] Furthermore, the method for obtaining the signal fluctuation characteristic values ​​includes: The sum of the absolute values ​​of the first-order differences of thermal resistance values ​​within the observation window is calculated to obtain the signal fluctuation characteristic value.

[0009] Furthermore, the method for obtaining the single-step frosting blockage increment includes: When the signal fluctuation characteristic value is greater than the preset normal airflow fluctuation threshold, the single-step frost blockage increment is set to zero; otherwise, a static state weighting coefficient that is negatively correlated with the signal fluctuation characteristic value is constructed, and the product of the current thermal resistance increment value and the static state weighting coefficient is used as the single-step frost blockage increment.

[0010] Furthermore, before calculating the thermal resistance of the thermoelectric module, the following steps are also included: If the cold end temperature is detected and is lower than the preset safe start-up temperature threshold, preventive defrosting will be performed first. Once the cold end temperature rises above the safe start-up temperature threshold, normal air-to-water generation mode will be entered.

[0011] Furthermore, before determining frosting blockage and controlling the thermoelectric module to perform defrosting, the process also includes: The system detects the temperature at the hot end. If the temperature at the hot end exceeds the preset safety limit, the defrosting operation is canceled and a shutdown alarm is issued.

[0012] Furthermore, after determining that frosting blockage has occurred and controlling the thermoelectric module to perform a defrosting operation, the process also includes: Set a thermal shock stabilization period, during which the calculation of the frosting blockage state value is disabled, and after the thermal shock stabilization period ends, the frosting blockage state value is reset to zero.

[0013] On the other hand, an air-to-water generator is also provided, which includes a thermoelectric module, a cooling fan, a temperature sensor, a voltage and current detection circuit, and a controller, the controller performing the steps of the method as described in any of the foregoing.

[0014] The present invention has the following beneficial effects: This invention obtains the instantaneous input power, cold end temperature, and hot end temperature of the thermoelectric module and calculates the thermal resistance value. It then uses historical thermal resistance data to establish a frost-free reference thermal resistance value to extract the thermal resistance increment. Simultaneously, it obtains signal fluctuation characteristic values ​​representing the intensity of airflow disturbance based on the dispersion of the thermal resistance value within the observation window. Furthermore, it combines these signal fluctuation characteristic values ​​with the thermal resistance increment value to obtain the single-step frost blockage increment, thereby constructing a frost blockage state value that only significantly increases when the thermal resistance increases and the airflow disturbance weakens. Based on this, it determines whether actual frost has formed and performs a defrosting operation. This method does not rely on additional sensors, but only utilizes its own electrical and thermodynamic parameters to achieve soft measurement, avoiding the problem of sensor failure in high-humidity condensation environments. It solves the problem in existing technologies that cannot distinguish between the natural increase in thermal resistance under low-temperature drying conditions and the increase in thermal resistance caused by frost blockage, leading to frequent defrosting or untimely defrosting, thus ensuring the accuracy of defrosting and water production efficiency. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages 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 of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of an air-to-water method based on thermoelectric refrigeration, provided as an embodiment of the present invention. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an air-to-water method and air-to-water generator based on thermoelectric refrigeration proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] The following description, in conjunction with the accompanying drawings, details a specific scheme for an air-to-water method based on thermoelectric refrigeration provided by the present invention.

[0020] Please see Figure 1The diagram illustrates a flow chart of an air-to-water method based on thermoelectric refrigeration according to an embodiment of the present invention. The method includes: Step S1: Obtain the instantaneous input power, cold end temperature and hot end temperature of the thermoelectric module and calculate the thermal resistance value of the thermoelectric module. Based on the historical data of the thermal resistance value in the time series, determine the frost-free reference thermal resistance value and obtain the thermal resistance increment value.

[0021] The cold end and hot end refer to the two end faces of the thermoelectric module that have different temperatures after being energized. The cold end is the end face of the thermoelectric module that absorbs heat and cools down after being energized. In an air-to-water generator, it is usually tightly attached to or directly integrated with the condenser fins. The low temperature generated by the cold end is conducted to the fin surface. When the fan drives air to flow through the fins, water vapor in the air condenses into liquid water upon encountering the low-temperature fin surface, thus extracting moisture from the air. The hot end is the end face of the thermoelectric module that releases heat and warms up after being energized. In an air-to-water generator, it is usually attached to the radiator. Its physical function is to dissipate the heat absorbed from the air by the cold end, along with the heat generated by the module itself, into the environment, maintaining the normal operation of the module.

[0022] During the actual operation of the air-to-water generator, changes in ambient temperature, fluctuations in air humidity, and the gradual growth of frost on the fin surface all affect the temperature difference between the cold and hot ends, thus affecting the electrical power required for the thermoelectric module to maintain this temperature difference. To extract state information from these complex coupling factors that can be used to determine frost blockage, this invention first obtains the instantaneous input power, cold end temperature, and hot end temperature of the thermoelectric module and calculates the thermal resistance value of the thermoelectric module.

[0023] The thermal resistance value at a single moment cannot determine whether the increase in thermal resistance is due to reduced heat load caused by a dry environment or airflow obstruction caused by frost blockage. Therefore, this invention introduces a frost-free reference thermal resistance value. This reference value is not fixed but is continuously determined based on historical data of thermal resistance over time, representing the expected thermal resistance level under "frost-free and normal heat exchange" conditions. Furthermore, the thermal resistance increment can be obtained by comparing the current thermal resistance value with the frost-free reference value. The purpose of extracting the thermal resistance increment is to eliminate interference from slowly changing factors such as ambient temperature and humidity, separating the portion of the "increased thermal resistance" phenomenon truly caused by frost blockage, and providing a reliable basis for accurately judging the frost condition. For example, in the dry environment of northern winters, the air itself has low moisture content, and the thermal resistance value may increase due to the natural decrease in cold-end temperature, but the thermal resistance increment is relatively gradual and accompanied by airflow fluctuations; however, during the frost process, the thermal resistance increment will continuously and rapidly increase as the frost layer thickens.

[0024] Preferably, in this embodiment of the invention, the method for calculating the thermal resistance value includes: When the instantaneous input power is greater than the minimum effective power threshold, the thermal resistance value is calculated using the difference between the hot end temperature and the cold end temperature as the numerator and the instantaneous input power as the denominator.

[0025] The minimum effective power threshold is generally taken as 5% of the maximum rated power. The maximum rated power is the maximum steady-state input power specified on the thermoelectric module's nameplate or datasheet, which is 60W in this embodiment. Thermal resistance and temperature difference are only calculated when the instantaneous input power exceeds the minimum effective power threshold. Under non-steady-state conditions such as insufficient power or standby, the temperature difference between the hot and cold ends may be zero or negative. In such cases, thermal resistance calculation is not performed until the power recovers above the minimum effective power threshold. Therefore, in the actual calculation process used for frosting detection, the temperature difference between the hot and cold ends will not be zero or negative.

[0026] To ensure the temporal alignment and numerical stability of the computation results, a sampling sequence index is established. A synchronous acquisition mechanism based on this is used. The sampling period is set to 0.1 seconds, and the sampling sequence index is... A monotonically increasing sequence of integers ( At each sampling moment, the hot-end temperature, cold-end temperature, and instantaneous input power are simultaneously acquired. As a specific example, in one implementation of this invention, the thermal resistance value is expressed by the formula: in, Indicates the first Thermal resistance value at each sampling time, in units of ; Indicates the first The hot end temperature at each sampling time; Indicates the first The cold junction temperature at each sampling time; Indicates the first The temperature difference span established at the hot and cold ends of the thermoelectric module at each sampling time; Indicates the first The instantaneous input power at each sampling moment.

[0027] Under the same instantaneous input power, when the fins are clean and the air duct is unobstructed, the cold air is quickly carried away, the temperature difference between the hot and cold ends is small, and the thermal resistance value will remain at a low and stable level. When the fins are gradually covered by frost or the air load changes, the cold end cannot effectively absorb the heat from the air, which leads to an increase in the temperature difference between the hot and cold ends, and the thermal resistance value will increase accordingly.

[0028] Preferably, in this embodiment of the invention, determining a frost-free reference thermal resistance value based on historical data over time of the thermal resistance value includes: When the frosting blockage state value is zero, the frost-free reference thermal resistance value is dynamically updated based on historical thermal resistance data. When the frosting blockage state value is greater than zero, the frost-free reference thermal resistance value is locked, so that the frost-free reference thermal resistance value remains unchanged from the most recent value.

[0029] When the frost blockage status value is zero, the current state is considered clean and unblocked. The frost-free reference thermal resistance value is dynamically updated based on historical thermal resistance data to adapt to slowly changing factors such as ambient temperature and humidity, ensuring that the frost-free reference thermal resistance value always reflects the "normal heat exchange level". When the frost blockage status value is greater than zero, it indicates that a potential frost trend has been detected. Even if it has not yet reached the point where defrosting is required, the baseline value is immediately locked and no longer updated. This prevents the frost-free reference thermal resistance value from gradually drifting and recording the frost state as a new normal state, thus avoiding missed detections.

[0030] Specifically, in one implementation method of this invention, a first-in-first-out (FIFO) queue is used to record historical data of thermal resistance values ​​over time. The queue length should be selected to meet the following requirements: it should be able to quickly respond to minute-level changes in ambient temperature; at the same time, it should be able to smooth out second-level transient disturbances and provide a stable reference. In this embodiment, when the sampling period is 0.1 seconds, the queue length is set to... It can store historical thermal resistance data for the past 12 seconds.

[0031] When the queue is not full, the incremental value of thermal resistance is set to zero, and the frosting blockage state value does not need to be calculated at this time. When the queue is full, the frosting blockage state value at the previous sampling time is read. If it is zero, the current thermal resistance value is pushed to the tail of the queue, and the earliest data at the head of the queue is removed, keeping the queue length unchanged. Subsequently, the arithmetic mean of all data in the queue is calculated as the current frost-free reference thermal resistance value. When the frosting blockage state value is greater than zero, new data is stopped being pushed into the queue, the queue contents are kept unchanged, and the frost-free reference thermal resistance value is set to remain unchanged at the most recent value.

[0032] Preferably, in this embodiment of the invention, the method for obtaining the thermal resistance increment value includes: The difference between the thermal resistance value and the frost-free reference thermal resistance value is compared with a preset dead zone threshold. When the difference is less than the preset dead zone threshold, the thermal resistance increment is set to zero; otherwise, the difference is used as the thermal resistance increment.

[0033] The frost-free reference thermal resistance represents the expected thermal resistance level under completely frost-free and normal heat exchange conditions. Subtracting the frost-free reference thermal resistance from the current thermal resistance value yields the absolute deviation from the current value. The purpose of introducing a preset dead-zone threshold is to filter out the sensor's own zero-point drift, ADC quantization error, and normal minor thermal fluctuations, ensuring that only increases in thermal resistance exceeding a certain significant level are counted as valid increments. The preset dead-zone threshold range is... A higher value indicates greater environmental interference. The specific value should be determined based on the actual situation. In this embodiment, the preset dead zone threshold is set to [value missing]. .

[0034] Furthermore, before calculating the thermal resistance of the thermoelectric module, the following steps are also included: If the cold end temperature is detected and is lower than the preset safe start-up temperature threshold, preventive defrosting will be performed first. Once the cold end temperature rises above the safe start-up temperature threshold, normal air-to-water generation mode will be entered.

[0035] During power-on initialization or abnormal reset phases due to frost blockage, to prevent subsequent baseline construction errors caused by unmelted frost remaining on the fins, the current cold-end fin temperature should be checked before proceeding to subsequent data processing. The preset safe start-up temperature threshold should be higher than the freezing point with sufficient margin to ensure that the cold-end temperature truly returns to a frost-free state at startup, thereby avoiding baseline construction errors and subsequent logic deadlocks caused by residual cold or trace ice crystals. In this embodiment of the invention, the safe start-up temperature threshold is set to... If set too low (e.g.) ), which can easily lead to missed detections due to errors or thermal inertia; setting the value too high (e.g.) If this is not done, preventative defrosting may be performed frequently when necessary, wasting energy and time.

[0036] Step S2: Obtain signal fluctuation characteristic value based on the dispersion of thermal resistance value within the observation window; obtain single-step frosting blockage increment based on the signal fluctuation characteristic value and the thermal resistance increment value; accumulate the single-step frosting blockage increment over time to obtain frosting blockage state value.

[0037] Because the increase in thermal resistance under normal conditions and the increase in thermal resistance caused by frost blockage may exhibit similar numerical characteristics in terms of the increase in thermal resistance, it is impossible to distinguish whether frost blockage exists based solely on the magnitude of the increase in thermal resistance. This is because the two are fundamentally different. Under normal conditions of low temperature and dryness, airflow remains unobstructed when thermal resistance increases, while airflow is gradually blocked by the frost layer when thermal resistance increases due to frost blockage.

[0038] When the fins are clean and the airflow channels are unobstructed, the air driven by the fan is not completely smooth, but rather exhibits slight turbulence and eddy current disturbances. These disturbances are transferred to the cold end of the thermoelectric module through heat transfer, causing the thermal resistance value to exhibit natural, small-amplitude random fluctuations over time. However, as the frost layer gradually fills the fin gaps and the airflow is effectively blocked, these random disturbances caused by the airflow are smoothly suppressed by the heat capacity and insulation effect of the frost layer, and the time-series waveform of the thermal resistance signal tends to flatten, with the fluctuations disappearing. Therefore, based on the degree of dispersion of the thermal resistance value within the observation window, signal fluctuation characteristic values ​​are obtained within each observation window. These signal fluctuation characteristic values ​​quantitatively describe the activity of the current airflow disturbance on the thermal resistance signal: the larger the value, the stronger the airflow disturbance and the more unobstructed the channel; the smaller the value, the closer the airflow is to stillness and the channel may be blocked.

[0039] Subsequently, the thermal resistance increment value obtained at the current moment is fused with the signal fluctuation characteristic value to generate the single-step frosting blockage increment. The thermal resistance increment value reflects the degree of deterioration in heat conversion, while the signal fluctuation characteristic value reflects the intensity of disturbance caused by airflow. Only when the thermal resistance increment value is significant and the signal fluctuation weakens will the single-step frosting blockage increment have a large value; conversely, if the thermal resistance increment value is large but the signal fluctuation is still obvious, it indicates that the airflow is unobstructed and the increase in thermal resistance is only due to the natural increase caused by the dry environment, and the single-step frosting blockage increment is suppressed to near zero.

[0040] Finally, the incremental frosting blockage at each moment is continuously accumulated over time to form a frosting blockage state value that evolves over time. The accumulation process will only see the frosting blockage state value steadily increase if the conditions of high thermal resistance increment and low airflow disturbance are continuously met; once the airflow recovers or the thermal resistance decreases, the growth of the frosting blockage state value will stop or even be reset.

[0041] The frosting blockage state value is initially 0 when the thermoelectric module is first started and no thermal resistance increase or fluctuation characteristics have been detected, representing a completely clean and unblocked initial state. As a specific example, in one implementation of this invention, the frosting blockage state value is expressed by the formula: in, Indicates the first Frosting and blockage status values ​​at each sampling time; Indicates the first Frosting and blockage status values ​​at each sampling time; Indicates the first The incremental frosting blockage at each sampling time.

[0042] It should be noted that in this embodiment of the invention, the frosting blockage state value is calculated using an accumulation mechanism. After a minor single-step frosting blockage increment is generated by an occasional environmental disturbance, the frosting blockage state value will be greater than zero and will never fall back. At this point, the trigger condition locks the frost-free reference thermal resistance value, causing the update mechanism to fail. The unidirectional accumulation in the non-frost environment will eventually reach the blockage judgment threshold. Therefore, the frosting blockage state value is reset between two defrosting operations. When the single-step frosting blockage increment is zero for a consecutive preset duration, the frosting blockage state value is reset to zero, and the locking of the frost-free reference thermal resistance value is released. In this embodiment of the invention, the preset duration is 30 seconds. 30 seconds is sufficient to cover normal disturbances such as fan speed fluctuations and power ripple. If no single-step frosting blockage increment is generated within 30 seconds, it indicates that either the airflow has fully recovered after the disturbance disappears under dry conditions, or a steady state has been reached. In this case, it is safe to allow the frosting blockage state value to be reset to zero. In practice, the preset duration can be adjusted according to the sampling frequency, environmental noise level, and desired response speed.

[0043] Preferably, in this embodiment of the invention, the method for obtaining the signal fluctuation characteristic value includes: The sum of the absolute values ​​of the first-order differences of thermal resistance values ​​within the observation window is calculated to obtain the signal fluctuation characteristic value.

[0044] In this embodiment of the invention, the dispersion of the thermal resistance value within the observation window is represented by the sum of the absolute values ​​of the first-order differences of the thermal resistance values ​​within the observation window. To quantify the characteristic that random fluctuations caused by airflow in the thermoelectric module are significantly smoothed and suppressed over a certain period, resulting in flattened signal fluctuations, a short-period observation window length is introduced. The selection of this short-period observation window length aims to cover at least one complete airflow disturbance cycle while maintaining a rapid response to state changes. In this embodiment, when the sampling period is 0.1 seconds, the value is set to 10, corresponding to a duration of 1 second.

[0045] As a specific example, in one implementation of this invention, the signal fluctuation characteristic value is expressed by the formula: in, Indicates the first Signal fluctuation characteristic values ​​at each sampling time; Indicates the length of the short-period observation window; This represents the loop index in the summation operation; Indicates the first The thermal resistance value of the thermoelectric module calculated at each sampling time; Indicates the first The thermal resistance value of the thermoelectric module is calculated at each sampling time.

[0046] Preferably, in this embodiment of the invention, the method for obtaining the single-step frosting blockage increment includes: When the signal fluctuation characteristic value is greater than the preset normal airflow fluctuation threshold, the single-step frost blockage increment is set to zero; otherwise, a static state weighting coefficient that is negatively correlated with the signal fluctuation characteristic value is constructed, and the product of the current thermal resistance increment value and the static state weighting coefficient is used as the single-step frost blockage increment.

[0047] In this embodiment of the invention, the static state weighting coefficient is obtained by adding a very small correction factor to the signal fluctuation characteristic value and then taking its reciprocal. As a specific example, in a specific implementation of this embodiment, the static state weighting coefficient is expressed by the formula: in, Indicates the first The static state weighting coefficient at each sampling time point, expressed in units of ; Indicates the first Signal fluctuation characteristic values ​​at each sampling time; This is a very small correction factor. In this embodiment, Values This has a dual physical significance: preventing overflow when the denominator is zero and limiting the maximum upper limit of the weighting coefficient for the static state. When the characteristic value of the signal fluctuation approaches zero, it means that the signal fluctuation has almost disappeared, the airflow disturbance has been completely suppressed by the frost layer, and the fin gap has been severely blocked. At this time, the weighting coefficient for the static state has almost reached its maximum value, which can quickly accumulate the value of the frosting blockage state.

[0048] As a specific example, in one implementation of this invention, the incremental frosting blockage in a single step is expressed by the formula: in, Indicates the first The incremental frosting blockage at each sampling time; Indicates the first The static state weighting coefficients at each sampling time; Indicates the first The thermal resistance increment value at each sampling time; the final single-step frosting blockage increment is a dimensionless increment value.

[0049] It should be noted that even under dry, non-frost conditions, the incremental amount of single-step frost blockage will continue to increase, thereby triggering a defrosting operation. Therefore, a preset normal airflow fluctuation threshold is introduced, which is set to [value missing] in this embodiment of the invention. When the signal fluctuation characteristic value is greater than the preset normal airflow fluctuation threshold, the airflow is considered unobstructed, and the single-step contribution is zero. At this time, the single-step frost blockage increment is set to zero to prevent misjudgment caused by the slow accumulation of single-step frost blockage increment.

[0050] Step S3: When the frosting blockage status value exceeds the preset blockage judgment threshold, frosting blockage is determined, and the thermoelectric module is controlled to perform defrosting operation.

[0051] When the frosting and blockage status value accumulates continuously and gradually approaches and eventually exceeds the preset blockage judgment threshold, it is determined that the fin gap has been severely obstructed by the frost layer. At this point, a defrosting operation must be performed to restore water production capacity. This judgment process is not an instantaneous decision, but is based on a comprehensive assessment of historical cumulative trends, avoiding erroneous judgments caused by single data fluctuations or instantaneous environmental interference.

[0052] The essence of the frost blockage status value is the quantification of the degree to which the dual conditions of "abnormally increased thermal resistance" and "disappearance of airflow disturbance" are continuously met. When the accumulated amount exceeds the preset blockage judgment threshold, it means that the frost layer has developed from local crystallization into a solid blockage covering most of the fin surface. If it is not cleaned in time, the airflow will drop sharply, the cooling power will be ineffectively consumed, and the water production efficiency will approach zero. Traditional timed defrosting schemes may not have reached the preset cycle at this time, resulting in the equipment being in an inefficient or even ineffective operating state for a long time; while schemes based on single-point temperature thresholds may misjudge in low-temperature and low-humidity environments and prematurely interrupt the cooling process.

[0053] When the frosting and blockage value exceeds a preset blockage threshold, this invention actively controls the thermoelectric module to switch operating modes and utilizes the reversibility of the Peltier effect to perform defrosting. The specific defrosting operation is as follows: (1) Cut off cooling: Immediately cut off the positive cooling current of the thermoelectric module to stop the generation of cooling capacity.

[0054] (2) Reverse heating: Input a reverse pulse current to the thermoelectric module. The amplitude of the reverse current is set to 80% of the rated operating current, and the duration is set to a fixed duration (e.g., 15 seconds). During this period, the thermoelectric module rapidly pumps the heat from the hot end to the root of the cold end fins, causing the microscopic contact interface between the frost layer and the fins to melt rapidly, resulting in the frost layer losing its adhesion.

[0055] (3) Wind-assisted: During reverse heating and for 5 seconds after heating ends, the cooling fan runs at full speed. The dynamic pressure generated by the airflow, combined with gravity, pushes the frost layer that has lost its root adhesion away from the fin gap, achieving rapid cleaning.

[0056] By changing the direction of the driving current, the cold end, which was originally for cooling, is transformed into the heating end, rapidly increasing the fin temperature to melt the frost layer. This method eliminates the need for additional electric heating wires or complex mechanical defrosting devices, relying entirely on the physical characteristics of the thermoelectric module itself, resulting in a simple structure and rapid response. Compared to traditional natural defrosting during shutdown, this method can complete frost removal within seconds to tens of seconds, after which it automatically resumes cooling mode and restarts the water production cycle.

[0057] The frosting blockage state value is obtained by accumulating the single-step frosting blockage increment at each sampling point. If the frosting blockage state is stable, the single-step frosting blockage increment at each sampling moment is approximately constant. As a specific example, in a specific implementation of this invention, the calculation of the preset blockage determination threshold is expressed by the formula: in, This indicates the preset congestion detection threshold; This represents the typical single-step frosting blockage increment constant under nominal frosting conditions; the example value is 20. This represents the sampling frequency; when the sampling period is 0.1 seconds, it takes the value... ; The expected response time represents the preset time required from the start of a stable and continuous frosting blockage state to the determination and triggering of defrosting. An example value of 5 seconds is used. The final preset blockage determination threshold is a dimensionless value. An example calculation result of 1000 indicates that frosting blockage is determined when the accumulated frosting blockage value exceeds 1000.

[0058] Furthermore, before determining frosting blockage and controlling the thermoelectric module to perform defrosting, the process also includes: The system detects the temperature at the hot end. If the temperature at the hot end exceeds the preset safety limit, the defrosting operation is canceled and a shutdown alarm is issued.

[0059] When the cooling fan malfunctions and stops, the thermal resistance increases sharply when airflow stops, exhibiting characteristics identical to frost formation. This causes the frost blockage value to rapidly exceed the preset blockage threshold. However, at this point, the hot-end temperature of the thermoelectric module will abnormally rise. If reverse heating is applied at this time, it will exacerbate the overheating of the thermoelectric module, potentially leading to burnout. Therefore, it is necessary to check the current hot-end temperature and set a preset safe limit temperature. When the temperature exceeds the safety limit, the power should be cut off and an alarm should be triggered to ensure the safety of thermoelectric cooling.

[0060] Furthermore, after determining that frosting blockage has occurred and controlling the thermoelectric module to perform a defrosting operation, the process also includes: Set a thermal shock stabilization period, during which the calculation of the frosting blockage state value is disabled, and after the thermal shock stabilization period ends, the frosting blockage state value is reset to zero.

[0061] After the defrosting operation, the cold junction temperature of the thermoelectric module undergoes a drastic rise and recooling process. During this time, the calculated thermal resistance value of the thermoelectric module is in a non-steady state. Directly analyzing the frosting blockage status value may lead to misjudgment. Therefore, a thermal shock stabilization period of 30 seconds is set to ensure that the frosting status is not misjudged, resulting in repeated defrosting. During the thermal shock stabilization period, data acquisition continues, but the thermal resistance increment value is not calculated, and the frosting blockage status value is not updated. After the thermal shock stabilization period ends, the frosting blockage status value is reset to zero.

[0062] This invention obtains the instantaneous input power, cold end temperature, and hot end temperature of the thermoelectric module and calculates the thermal resistance value. It then uses historical thermal resistance data to establish a frost-free reference thermal resistance value to extract the thermal resistance increment. Simultaneously, it obtains signal fluctuation characteristic values ​​representing the intensity of airflow disturbance based on the dispersion of the thermal resistance value within the observation window. Furthermore, it combines these signal fluctuation characteristic values ​​with the thermal resistance increment value to obtain the single-step frost blockage increment, thereby constructing a frost blockage state value that only significantly increases when the thermal resistance increases and the airflow disturbance weakens. Based on this, it determines whether actual frost has formed and performs a defrosting operation. This method does not rely on additional sensors, but only utilizes its own electrical and thermodynamic parameters to achieve soft measurement, avoiding the problem of sensor failure in high-humidity condensation environments. It solves the problem in existing technologies that cannot distinguish between the natural increase in thermal resistance under low-temperature drying conditions and the increase in thermal resistance caused by frost blockage, leading to frequent defrosting or untimely defrosting, thus ensuring the accuracy of defrosting and water production efficiency.

[0063] On the other hand, the present invention also provides an air-to-water generator based on thermoelectric cooling, the air-to-water generator including a thermoelectric module, a cooling fan, a temperature sensor, a voltage and current detection circuit, and a controller, the controller performing the steps of the method as described in any of the foregoing claims.

[0064] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0065] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A method for producing water from air based on thermoelectric refrigeration, characterized in that, The method includes: The instantaneous input power, cold end temperature, and hot end temperature of the thermoelectric module are obtained, and the thermal resistance value of the thermoelectric module is calculated. Based on the historical data of the thermal resistance value in the time series, the frost-free reference thermal resistance value is determined, and the thermal resistance increment value is obtained. The signal fluctuation characteristic value is obtained based on the dispersion of the thermal resistance value within the observation window. The single-step frost blockage increment is obtained by combining the signal fluctuation characteristic value with the thermal resistance increment value. The single-step frost blockage increment is accumulated over time to obtain the frost blockage state value. When the frosting blockage value exceeds the preset blockage judgment threshold, frosting blockage is determined, and the thermoelectric module is controlled to perform defrosting operation.

2. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, The method for calculating the thermal resistance value includes: When the instantaneous input power is greater than the minimum effective power threshold, the thermal resistance value is calculated using the difference between the hot end temperature and the cold end temperature as the numerator and the instantaneous input power as the denominator.

3. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, Determining a frost-free reference thermal resistance value based on historical data of the aforementioned thermal resistance value over time includes: When the frosting blockage state value is zero, the frost-free reference thermal resistance value is dynamically updated based on historical thermal resistance data. When the frosting blockage state value is greater than zero, the frost-free reference thermal resistance value is locked, so that the frost-free reference thermal resistance value remains unchanged from the most recent value.

4. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, The method for obtaining the thermal resistance increment value includes: The difference between the thermal resistance value and the frost-free reference thermal resistance value is compared with a preset dead zone threshold. When the difference is less than the preset dead zone threshold, the thermal resistance increment is set to zero; otherwise, the difference is used as the thermal resistance increment.

5. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, The method for obtaining the signal fluctuation characteristic values ​​includes: The sum of the absolute values ​​of the first-order differences of thermal resistance values ​​within the observation window is calculated to obtain the signal fluctuation characteristic value.

6. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, The method for obtaining the single-step frosting blockage increment includes: When the signal fluctuation characteristic value is greater than the preset normal airflow fluctuation threshold, the single-step frost blockage increment is set to zero; otherwise, a static state weighting coefficient that is negatively correlated with the signal fluctuation characteristic value is constructed, and the product of the current thermal resistance increment value and the static state weighting coefficient is used as the single-step frost blockage increment.

7. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, Before calculating the thermal resistance of the thermoelectric module, the following steps are also included: If the cold end temperature is detected and is lower than the preset safe start-up temperature threshold, preventive defrosting will be performed first. Once the cold end temperature rises above the safe start-up temperature threshold, normal air-to-water generation mode will be entered.

8. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, Before determining if frosting is blocked and controlling the thermoelectric module to perform defrosting, the process also includes: The system detects the temperature at the hot end. If the temperature at the hot end exceeds the preset safety limit, the defrosting operation is canceled and a shutdown alarm is issued.

9. The air-to-water method based on thermoelectric refrigeration according to claim 1, characterized in that, After determining that frosting blockage has occurred and controlling the thermoelectric module to perform a defrosting operation, the process also includes: Set a thermal shock stabilization period, during which the calculation of the frosting blockage state value is disabled, and after the thermal shock stabilization period ends, the frosting blockage state value is reset to zero.

10. An air-to-water generator based on thermoelectric cooling, the air-to-water generator comprising a thermoelectric module, a cooling fan, a temperature sensor, a voltage and current detection circuit, and a controller, characterized in that, The controller performs the steps of the method as described in any one of claims 1 to 9.

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