A temperature control method and system for a walk-in test chamber

Abstract

The present invention relates to the technical field of data processing, and in particular, to a temperature control method and system for a walk-in test chamber. The method includes: obtaining in real time the temperature difference sequence and the normalized temperature value of each position in the test chamber including the current moment, as well as the power difference sequence of each heating element including the current moment; determining the objective function of the heating effectiveness of each position, and obtaining the backtracking time that maximizes the heating effectiveness of each position at the current moment; calculating the temperature control lag degree of the test chamber at the current moment; obtaining the temperature control quantity at the current moment by using the PID algorithm; calculating the weighted temperature control quantity at the current moment; and performing temperature adjustment according to the weighted temperature control quantity to complete the temperature control of the walk-in test chamber. The present invention constructs the objective function of the heating effectiveness, solves the optimal backtracking time, and calculates the weighted temperature control quantity, thereby reducing the temperature overshoot phenomenon caused by hysteresis and improving the accuracy of temperature adjustment.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and particularly to a temperature control method and system for a walk-in test chamber. Background Art

[0002] A walk-in test chamber is a large-scale environmental test equipment with a relatively large internal space, which can simulate various environmental conditions such as temperature, humidity, and light. It is used in many industries such as electronics, automotive, and aerospace to test the performance and reliability of products under different environments, such as the temperature resistance test of electronic products and the aging test of materials. Since temperature is one of the key factors affecting product performance, accurate temperature control can ensure the stability and repeatability of test conditions, make the product test results more accurate and comparable, help enterprises discover product defects in advance, improve product design, enhance product quality, strengthen market competitiveness, and ensure the stability and safety of products in actual use.

[0003] The patent application document with the publication number CN117631723A discloses a PID automatic temperature control device, including: a 24V DC power supply, a 485 conversion analog module, an analog to 485 module, a current transmitter, a thermal resistance temperature sensor probe, an RS485 communication twisted pair, a PLC controller, an analog control module, and a direct-fired engine proportional valve; the thermal resistance temperature sensor probe converts and amplifies the real-time collected temperature into an electric current signal through the current transmitter, converts the electric current signal into a 485 communication message through the analog to 485 module, and transmits it over a long distance through the RS485 communication twisted pair to the 485 to analog module and the PLC controller. The 485 to analog module restores the 485 communication message into an electric current signal and outputs it to the input end of the analog control module, and the analog control module collects and transmits the signal to the PLC controller.

[0004] However, the above patent application document does not solve the problem that when controlling the temperature of a walk-in test chamber through the PID algorithm, due to the large internal space of the walk-in test chamber and the time required for heat transfer, there is a lag in temperature control, resulting in an overshoot phenomenon of the temperature, inaccurate temperature regulation, and affecting the temperature control of the walk-in test chamber. Summary of the Invention

[0005] In order to solve the problem that when controlling the temperature of a walk-in test chamber through the PID algorithm, due to the large internal space of the test chamber and the time required for heat transfer, there is a lag in temperature control, resulting in an overshoot phenomenon of the temperature, inaccurate temperature regulation, and affecting the temperature control of the walk-in test chamber, the present invention provides a temperature control method and system for a walk-in test chamber.

[0006] In a first aspect, the present invention provides a temperature control method for a walk-in test chamber, adopting the following technical solution:

[0007] A temperature control method for a walk-in test chamber, comprising: obtaining in real time the temperature difference sequence and the normalized temperature value of each position in the test chamber including the current moment, and the power difference sequence of each heating element including the current moment; for any position, based on the values in the temperature difference sequence of each moment within the time period to which the current moment belongs at this position, the values in the power difference sequence corresponding to the moment before the backtracking time of each moment within the time period to which the current moment belongs, and the Euclidean distance from each heating element to this position, construct an objective function for the heating effectiveness at this position at the current moment, and use the least squares method to solve the objective function to obtain the backtracking time that maximizes the heating effectiveness at this position at the current moment as the target backtracking time for this position; based on the variance of the normalized temperature values at each position at the current moment and the maximum value among the target backtracking times of all positions, calculate the temperature control lag degree of the test chamber at the current moment; take the mean value of the temperature values at each position at the current moment as the temperature of the test chamber at the current moment, and based on the temperature of the test chamber at the current moment and the preset temperature curve, use the PID algorithm to obtain the temperature control quantity at the current moment; based on the temperature of the test chamber, the value at the current moment in the preset temperature curve, the temperature control lag degree, and the temperature control quantity, calculate the weighted temperature control quantity at the current moment; perform temperature adjustment according to the weighted temperature control quantity to complete the temperature control of the walk-in test chamber.

[0008] The beneficial effects are as follows: By obtaining the temperature difference sequence and the power difference sequence in real time and combining the heating effectiveness optimization control strategy, the temperature control lag is effectively reduced, temperature overshoot is avoided, and the accuracy of temperature adjustment is improved; By calculating the backtracking time and the temperature control lag degree, the control parameters are dynamically adjusted to avoid temperature over-fluctuation and overshoot phenomena and ensure stable temperature changes; Due to the slow temperature change caused by the large space inside the test chamber, this method can effectively solve the lag problem and enhance the adaptability of the system to the large-space environment; By adjusting the heating effectiveness in real time, the temperature changes at different positions in the test chamber are ensured to be synchronized, the temperature is kept evenly distributed, and local temperature fluctuations are avoided.

[0009] Further, the obtaining methods of the temperature difference sequence and the power difference sequence are: filtering and denoising the collected temperature sequences of each position in the test chamber including the current moment and the power sequences of each heating element, and then performing first-order differences on the denoised temperature sequences of each position and the power sequences of each heating element to obtain the temperature difference sequence and the power difference sequence.

[0010] The beneficial effects are as follows: Through filtering and denoising processing, the noise interference in the temperature and power data is reduced, making the data more stable and reliable, providing an accurate basis for subsequent analysis and control; the first-order difference processing can extract the change rates of temperature and power, enabling the control system to better understand the dynamic characteristics of temperature changes, and thus making more accurate control decisions.

[0011] Further, the filtering and denoising adopts Gaussian filtering.

[0012] Further, the method for obtaining the normalized temperature value is: performing linear normalization processing on the temperature sequences at each position after denoising to obtain the normalized temperature values at each position at the current moment.

[0013] Further, the objective function is:

[0014] ; where is the heating effectiveness at position at the current moment, is the number of moments within the time period to which the current moment belongs, is the value in the temperature difference sequence at position at the -th moment within the time period to which the current moment belongs, is the number of heating elements, is the -th moment in the power difference sequence of the -th heating element, is the backtracking time, and its value range is , is the Euclidean distance from the -th heating element to position , is the normalization function, is the absolute value symbol.

[0015] The beneficial effects are as follows: By calculating the difference between the temperature difference and the power difference, the objective function can accurately evaluate the heating effectiveness of the heating system at each position, thereby reflecting whether the system heating reaches the expected effect; by introducing the Euclidean distance between the heating element and the target position, the objective function effectively adjusts the influence of different heating elements on the target position, ensuring that the influence weight of the heating element far from the target position on the temperature is small, and improving the accuracy of the heating system; by obtaining the backtracking time corresponding to the optimal solution, the objective function can take into account the influence of historical power on the current temperature, optimize the lag characteristic during heat transfer, and thus improve the accuracy of the control system.

[0016] Further, the temperature control lag degree satisfies the following relational expression:

[0017] ; wherein, is the temperature control lag degree of the test chamber at the current moment, is the variance of the normalized temperature values at each position at the current moment, is the maximum value of the target backtracking time at all positions at the current moment.

[0018] The beneficial effects are as follows: By combining the variance of the normalized temperature values at each position at the current moment and the maximum value of the target backtracking time at all positions, the temperature control lag degree is quantified, which is convenient for monitoring and evaluating the temperature control response time of the system and provides real-time feedback; and based on the magnitude of the temperature control lag degree, potential problems existing in the control system or equipment can be identified, such as slow heating / cooling response, uneven temperature, etc., and data support is provided for optimization measures.

[0019] Furthermore, the weighted temperature control quantity satisfies the following relational expression:

[0020] ; wherein, is the weighted temperature control quantity at the current moment, is the temperature of the test chamber at the current moment, is the value in the preset temperature curve at the current moment, is the temperature control lag degree of the test chamber at the current moment, is the temperature control quantity at the current moment, is the absolute value symbol.

[0021] The beneficial effects are as follows: By calculating the temperature control error in real time and dynamically adjusting the temperature control quantity according to the temperature control lag degree, the system's precise response is ensured, and the temperature deviation is reduced; introducing the lag factor can compensate for the lag effect in the system's heating or cooling process, optimize the temperature adjustment speed, and avoid temperature overshoot or insufficiency caused by lag; by dynamically adjusting the control quantity, the adaptability of the system in the face of different environments or working states is enhanced, ensuring that the temperature control system can work stably and maintain a high control precision; by flexibly adjusting the control quantity according to the actual temperature deviation and lag situation, the system is prevented from overheating or overcooling, thereby improving energy efficiency and reducing unnecessary energy consumption.

[0022] In the second aspect, the present invention provides a walk-in test chamber temperature control system, adopting the following technical solution:

[0023] A walk-in test chamber temperature control system includes: a processor and a memory, and the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the above-mentioned walk-in test chamber temperature control method is implemented.

[0024] By adopting the above technical solution, a computer program is generated based on the above-mentioned temperature control method for a walk-in test chamber and stored in a memory to be loaded and executed by a processor, so as to manufacture a terminal device according to the memory and the processor, which is convenient to use.

[0025] The present invention has the following technical effects:

[0026] Due to the large internal space of the test chamber, the time-consuming heat transfer leading to hysteresis in temperature control, as well as temperature overshoot and inaccurate regulation, etc., the present invention constructs an objective function of heating effectiveness and uses the least squares method to solve for the target backtracking time at each position, which helps to accurately grasp the effective situation of heating at different positions, takes into account the key factor of heat transfer time difference, and thus can better layout the temperature regulation in advance, reduce the temperature overshoot phenomenon caused by hysteresis, and improve the accuracy of temperature regulation. At the same time, the temperature control hysteresis degree is calculated based on the variance of the normalized temperature values at each position and the maximum value among the target backtracking times of all positions, comprehensively considering the temperature differences at different positions inside the test chamber and the overall hysteresis situation; the weighted temperature control amount is calculated by combining the test chamber temperature, the preset temperature curve, the temperature control hysteresis degree, and the temperature control amount. This way of comprehensively considering multiple factors makes the final temperature regulation more in line with the actual situation of the test chamber, realizes more accurate and scientific temperature control, ensures the temperature control effect of the walk-in test chamber, and meets the strict requirements of relevant tests for the temperature environment. Through the above operations, the deficiencies of the PID algorithm in dealing with the temperature control hysteresis problem of large-space test chambers are made up for, the application effect of the PID algorithm in test chamber temperature control is further optimized, the quality and stability of the overall temperature control are improved, and the temperature inside the test chamber can change more stably and accurately according to the preset temperature curve. Description of the Drawings

[0027] By referring to the following detailed description with reference to the drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understood. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts.

[0028] Figure 1 It is a flowchart of the method in the temperature control method for a walk-in test chamber according to an embodiment of the present invention. Detailed Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] It should be understood that when terms such as "first", "second", etc. are used in the claims, the description and the drawings of the present invention, they are only used to distinguish different objects and not to describe a specific order. The terms "comprising" and "including" used in the description and claims of the present invention indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0031] An embodiment of the present invention discloses a temperature control method for a walk-in test chamber. Referring to Figure 1 , it includes steps S1 - S6:

[0032] S1: Real-time obtain the temperature difference sequence and the normalized temperature value at each position in the test chamber including the current moment, and the power difference sequence of each heating element including the current moment.

[0033] It should be noted that since the temperature reflects the actual thermal state at each position inside the test chamber and its change trend over time, and the power directly reflects the energy input provided by the heating elements in different time periods, it is helpful to identify the temperature uniformity and the heating efficiency when identifying the lag degree in the temperature control of the walk-in test chamber. Due to the large space of the test chamber, when installing sensors, it is necessary to ensure that the sensors can fully cover the test chamber space and capture the temperature changes in the key areas.

[0034] Temperature sensors are respectively arranged at the central positions of the four walls, the top, and the bottom of the test chamber to collect the temperature sequences at different positions in the test chamber in real time, and power sensors are arranged at the positions of each heating element in the test chamber to collect the power sequences of each heating element in the test chamber in real time. Set the sampling frequency of all sensors to be (which can be adjusted by the implementer according to the specific implementation situation).

[0035] Specifically, the acquisition methods of the temperature difference sequence and the power difference sequence are as follows:

[0036] Filter and denoise the collected temperature sequences at each position in the test chamber and the power sequences of each heating element including the current moment, and then perform a first-order difference on the denoised temperature sequences at each position and the power sequences of each heating element to obtain the temperature difference sequence and the power difference sequence.

[0037] Specifically, Gaussian filtering is used for the filtering and denoising.

[0038] Specifically, the acquisition method of the normalized temperature value is as follows:

[0039] Perform linear normalization processing on the denoised temperature sequences at each position to obtain the normalized temperature value at each position at the current moment.

[0040] S2: Determine the objective function of the heating effectiveness at each position, and obtain the backtracking time that maximizes the heating effectiveness at each position at the current moment.

[0041] It should be noted that since there is a certain lag when the heating element is heating, the power of the heating element corresponding to the dimension of the test chamber position at the current moment should be the power corresponding to the moment before the backtracking time of the heating element at the current moment. Therefore, the backtracking time that maximizes the positive correlation between the temperature change rate and the power change rate of the heating element within the time period to which each moment belongs can be found; since the distances between the heating elements and the position temperature sensors are different, the heat transfer efficiencies are different. To effectively identify the influence degree of each heating element on each position, it is also necessary to obtain the Euclidean distance between each heating element and each position, establish a spatial rectangular coordinate system with any vertex of the test chamber box as the origin, and then obtain the corresponding Euclidean distance.

[0042] For any position, based on the values in the temperature difference sequence at each moment within the time period to which the current moment belongs at this position, the values in the power difference sequence corresponding to the moments before the backtracking time of each moment within the time period to which the current moment belongs, and the Euclidean distance from each heating element to this position, construct the objective function of the heating effectiveness at this position at the current moment.

[0043] The implementer sets the length of the time period according to the specific implementation situation. For example, the current moment and the previous 5 moments.

[0044] Specifically, the objective function is:

[0045] ;

[0046] In the formula, is the heating effectiveness at position at the current moment, is the number of moments within the time period to which the current moment belongs, is the value in the temperature difference sequence at the th moment within the time period to which the current moment belongs at position , is the number of heating elements, is the th moment in the power difference sequence of heating element , is the backtracking time, and the value range is , is the heating element to the position Euclidean distance, is the normalization function, is the absolute value symbol.

[0047] Among them, is the position weighted by the Euclidean distance The average power before the backtracking time of each heating element at the place, when the position after adding the backtracking time The smaller the temperature change rate at the place and the difference between the average power, it represents that when adding the current time delay, the higher the possible degree of positive correlation between the temperature change rate of the test chamber and the power change rate of the heating element, and the higher the heating effectiveness.

[0048] It should be noted that the time delay that maximizes the heating effectiveness at the target sensor can be solved by the least squares method, that is, the backtracking time of the current moment of the heating element.

[0049] Using the least squares method to solve the objective function, the backtracking time that maximizes the heating effectiveness at the current moment at this position is used as the target backtracking time at this position.

[0050] S3: Calculate the temperature control lag degree of the test chamber at the current moment.

[0051] It should be noted that since the PID algorithm controls the temperature based on the difference between the measured temperature and the target temperature, however, the walk-in test chamber has a large space and it takes time for heat transfer. After the heating element generates heat, the distances between the heating element and different temperature sensors are different, and the heat transfer times are different, so there will be an uneven heat distribution during the heat transfer process. At this time, the measured temperature of the test chamber cannot reflect the real temperature. When directly using the PID algorithm to control the temperature, the heating element will continue to release heat when the heat transfer is not completed, resulting in a lag in temperature control and a temperature overshoot. Therefore, it is necessary to evaluate the temperature control lag degree at each moment of the test chamber to reduce the temperature overshoot; at the same time, the temperature control lag degree depends on the time when each heating element starts to generate heat and is transmitted to the temperature sensors at each position, so the variance of the normalized temperature values at each position of the test chamber at the current moment can be obtained respectively as the temperature uniformity and the backtracking time to calculate the temperature control lag degree; since the longest backtracking time among all the sensors in the test chamber determines the degree of temperature overshoot, the longest backtracking time among all the sensors in the test chamber can be selected to evaluate the temperature control lag degree of the test chamber.

[0052] Based on the variance of the normalized temperature values at each position at the current moment, and the maximum value among the target backtracking times at all positions, calculate the temperature control lag degree of the test chamber at the current moment.

[0053] Specifically, the temperature control lag degree satisfies the following relational expression:

[0054] ;

[0055] In the formula, is the temperature control lag degree of the test chamber at the current moment, is the variance of the normalized temperature values at each position at the current moment, is the maximum value of the target backtracking time at all positions at the current moment.

[0056] S4: Use the PID algorithm to obtain the temperature control quantity at the current moment.

[0057] It should be noted that the PID control algorithm is commonly used in industrial automation and process control. It can make fine adjustments according to the difference between the actual measured temperature and the set temperature to ensure that the temperature always remains within the ideal range. During the operation of the walk-in test chamber, when applying the PID algorithm to adjust the temperature, in order to facilitate subsequent adjustment of the temperature adjustment intensity, it is necessary to first obtain the temperature control quantity through the PID algorithm.

[0058] Take the mean value of the temperature values at each position at the current moment as the temperature of the test chamber at the current moment. Based on the temperature of the test chamber at the current moment and the preset temperature curve, use the PID algorithm to obtain the temperature control quantity at the current moment.

[0059] S5: Calculate the weighted temperature control quantity at the current moment.

[0060] It should be noted that when the temperature control lag degree of the test chamber is higher and the temperature is closer to the preset temperature, the lagging temperature control will cause the heating element to continue to release heat even when the total heat meets the temperature requirement, resulting in overshoot. At this time, it is more necessary to reduce the temperature control quantity obtained by the PID algorithm to avoid temperature overshoot.

[0061] Based on the temperature of the test chamber, the value at the current moment in the preset temperature curve, the temperature control lag degree, and the temperature control quantity, calculate the weighted temperature control quantity at the current moment.

[0062] Specifically, the weighted temperature control quantity satisfies the following relational expression:

[0063] ;

[0064] In the formula, is the weighted temperature control quantity at the current moment, is the temperature of the test chamber at the current moment, is the value at the current moment in the preset temperature curve, is the temperature control lag degree of the test chamber at the current moment, is the temperature control quantity at the current moment, is the absolute value symbol.

[0065] S6: Adjust the temperature according to the weighted temperature control quantity to complete the temperature control of the walk-in test chamber.

[0066] Obtain the adjustment magnitude using the weighted temperature control quantity at the current moment, adjust the PWM wave according to the adjustment magnitude, and then control the power of the heating element to complete the temperature control of the walk-in test chamber.

[0067] An embodiment of the present invention also discloses a temperature control system for a walk-in test chamber, including a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, a temperature control method for a walk-in test chamber according to the present invention is implemented.

[0068] The above system also includes other components well-known to those skilled in the art such as a communication bus and a communication interface. Their settings and functions are known in the art, so they will not be described in detail here.

[0069] In the present invention, the aforementioned memory can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, device, or apparatus. For example, a computer-readable storage medium can be any suitable magnetic storage medium or magneto-optical storage medium, or any other medium that can be used to store the required information and can be accessed by an application program, module, or both. Any such computer storage medium can be part of the device or accessible or connectable to the device.

[0070] Although this specification has shown and described multiple embodiments of the present invention, it is obvious to those skilled in the art that such embodiments are provided only by way of example. Those skilled in the art will think of many changes, alterations, and alternative ways without departing from the spirit and concept of the present invention. It should be understood that various alternative solutions to the embodiments of the present invention described herein can be adopted in the process of practicing the present invention.

[0071] The above are all preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A temperature control method for a walk-in test chamber, characterized in that, Including: Obtaining in real time the temperature difference sequence and normalized temperature value of each position in the test chamber at the current moment, and the power difference sequence of each heating element at the current moment; For any position, based on the values in the temperature difference sequence at each moment within the time period to which the current moment belongs at this position, the values in the power difference sequence at the corresponding moments before the retrospective time at each moment within the time period to which the current moment belongs, and the Euclidean distance from each heating element to this position, construct an objective function for the heating effectiveness at this position at the current moment, and use the least squares method to solve the objective function to obtain the retrospective time that maximizes the heating effectiveness at this position at the current moment as the target retrospective time for this position; Based on the variance of the normalized temperature values at each position at the current moment and the maximum value among the target retrospective times of all positions, calculate the temperature control lag degree of the test chamber at the current moment; Take the mean value of the temperature values at each position at the current moment as the temperature of the test chamber at the current moment, and based on the temperature of the test chamber at the current moment and the preset temperature curve, use the PID algorithm to obtain the temperature control quantity at the current moment; Based on the temperature of the test chamber, the value at the current moment in the preset temperature curve, the temperature control lag degree, and the temperature control quantity, calculate the weighted temperature control quantity at the current moment; Perform temperature adjustment according to the weighted temperature control quantity to complete the temperature control of the walk-in test chamber; The objective function is: ； Wherein, is the heating effectiveness at the current moment at the position , is the number of moments within the time period to which the current moment belongs, is the value in the temperature difference sequence at the -th moment within the time period to which the current moment belongs at the position , is the number of heating elements, is the value in the power difference sequence at the -th moment on the heating element , is the retrospective time, and its value range is , is the Euclidean distance from the heating element to the position , is the normalization function, is the absolute value symbol.

2. The temperature control method of a walk-in test chamber according to claim 1, characterized in that, The obtaining methods of the temperature difference sequence and the power difference sequence are: Filter and denoise the collected temperature sequences of each position in the test chamber at the current moment and the power sequences of each heating element, and then perform a first-order difference on the denoised temperature sequences of each position and the power sequences of each heating element to obtain the temperature difference sequence and the power difference sequence.

3. The temperature control method of a walk-in test chamber according to claim 2, wherein The filtering and denoising adopt Gaussian filtering.

4. The temperature control method of a walk-in test chamber according to claim 3, characterized in that, The obtaining method of the normalized temperature value is: Perform linear normalization processing on the denoised temperature sequences of each position to obtain the normalized temperature values at each position at the current moment.

5. A temperature control method for a walk-in test chamber according to claim 1, characterized in that, The temperature control lag degree satisfies the following relational expression: ； In the formula, is the temperature control lag degree of the test chamber at the current moment, is the variance of the normalized temperature values at each position at the current moment, is the maximum value of the target backtracking time at all positions at the current moment.

6. A temperature control method for a walk-in test chamber according to claim 1, characterized in that, The weighted temperature control quantity satisfies the following relational expression: ； In the formula, is the weighted temperature control value at the current moment, is the temperature of the test chamber at the current moment, is the value in the preset temperature curve at the current moment, is the temperature control lag degree of the test chamber at the current moment, is the temperature control value at the current moment, is the absolute value symbol.

7. A temperature control system for a walk-in test chamber, characterized in that, Including: A processor and a memory, the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the temperature control method of a walk-in test chamber according to any one of claims 1-6 is implemented.

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