Energy-saving temperature and humidity test chamber and flexible switching method of two-way PID controller thereof

Abstract

The present application relates to the technical field of control, especially to an energy-saving type temperature and humidity test chamber and a two-way PID controller flexible switching method thereof. The method first judges whether any preset switching condition is met, if yes, determines the switching type according to the change of the target value of the controlled object; then matches the corresponding relationship model according to the switching type to obtain the control component of the switched PID controller; finally calculates the output value of the switched PID controller according to the control component. The method can realize flexible switching of multiple PID controllers and improve the stability of temperature and humidity control.

Description

Technical Field

[0001] This invention relates to the field of control technology, and in particular to an energy-saving temperature and humidity test chamber and a flexible switching method for its bidirectional PID controller. Background Technology

[0002] A temperature and humidity test chamber is a device used to simulate different temperatures and humidity levels, and is widely used in reliability testing in fields such as electronics, materials, and medicine. The temperature and humidity of a temperature and humidity test chamber are typically controlled by a PID controller. For example, CN117772296A discloses a control method for a constant temperature and humidity test chamber. This method includes: acquiring a set test temperature and humidity; adjusting the temperature inside the constant temperature and humidity test chamber to the test temperature and adjusting the humidity inside the test chamber to the test humidity; placing the test sample inside the constant temperature and humidity test chamber for heat compensation; and maintaining the temperature inside the constant temperature and humidity test chamber at the test temperature and the test humidity. The processes of adjusting and maintaining the constant temperature and humidity test chamber to the test temperature and humidity, as well as the heat compensation process, are all controlled by a PID controller.

[0003] In practical applications, temperature and humidity are coupled, and if the same PID controller is used, the control parameters cannot be optimized independently. Therefore, to independently optimize control parameters to meet the needs of different controllers and the response characteristics of different controlled objects, different PID controllers can be used to control different processes; for example, one PID controller controls heating, and another controls cooling. However, if different PID controllers are used to control different processes, the type and / or parameters of the PID controller will usually be switched during the process of reaching or maintaining the target value. For example, the temperature of an energy-saving temperature and humidity test chamber is maintained at 30℃ (target value) by a heating PID controller. When the target value changes to 0℃, the controller will switch to a cooling PID controller to achieve the new target value. During the switching, the sudden change in parameter set does not match the controller's historical state, which will cause transient disturbances and thus disrupt the stability of temperature and humidity control.

[0004] Therefore, how to avoid instantaneous disturbances during switching to improve the stability of the control process is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the technical problem of instantaneous disturbances caused by the mismatch between the parameter set mutation and the controller's historical state, the present invention provides solutions in the following aspects.

[0006] In a first aspect, the present invention provides a flexible switching method for a bidirectional PID controller in an energy-saving temperature and humidity test chamber, applicable to an energy-saving temperature and humidity test chamber that uses different PID controllers to control heating, cooling, humidification, and dehumidification processes respectively. The method includes: if any preset switching condition is met, determining the switching type based on the change in the target value of the controlled object; the switching condition includes: the duration for which the output value of the PID controller before switching is lower than a set lower limit parameter is greater than or equal to a continuous threshold; matching a corresponding relational model according to the switching type to obtain the control component of the PID controller after switching; the relational model is used to determine the control component based on input data, the input data including the target value and the measured value of the controlled object, the control component including a proportional term, the proportional term being determined by the target value and the measured value; and calculating the output value of the PID controller after switching based on the control component.

[0007] Beneficial effects: By switching only after the switching conditions are met, control inertia can be dynamically compensated for with delay, and switching driven by physical properties can be achieved; by adopting different relational models according to different switching types, the flexible switching of the control process is ensured, thereby improving the stability of control.

[0008] Furthermore, the switching types include setpoint switching, process switching, and online switching of linear follower parameters; the switching type is determined according to the change of the target value of the controlled object, including: if the target value undergoes a step change, the determined switching type is setpoint switching; if the target value is constant, the determined switching type is process switching; if the target value changes linearly, the determined switching type is online switching of linear follower parameters.

[0009] Beneficial effects: By matching different relational models according to different switching types to calculate the control components of the PID controller after switching, it is ensured that the output value of the PID controller after switching can meet different performance requirements, while ensuring the stability of control.

[0010] Furthermore, the control components also include an integral term and a differential filter accumulation value.

[0011] Furthermore, the corresponding relational model is matched based on the switching type, including: if the switching type is a fixed-value to point-to-point switching, then the matched relational model is:

[0012]

[0013] In the formula, Let be the accumulated value of the differential filter of the PID controller after switching at time k. Let k be the integral term of the PID controller after the switch. Let k be the proportional term of the PID controller after switching. Let k be the target value of the controlled object at time k. Let k-1 be the target value of the controlled object. For differential time, Let k be the measured value of the controlled object at time k. The measured value of the controlled object at time k-1 is... The derivative term of the PID controller before the switching at time k-1 is... For the weight of the proportional term, These are the window parameters for the differential filter.

[0014] Beneficial effects: By incorporating the derivative term of the PID controller before switching into the calculation of the accumulated value of the derivative filter of the PID controller after switching, the derivative term of the PID controller before switching can be flexibly transferred to the PID controller after switching, avoiding instantaneous disturbances in the control output and achieving flexible switching of the control process. By incorporating the measured value and target value of the previous moment into the calculation of the integral term of the current moment, it can be ensured that the output value of the PID controller after switching is large enough to meet the requirements of fast response.

[0015] Further, calculating the output value of the switched PID controller based on the control components includes: calculating the differential term of the switched PID controller based on the accumulated value of the differential filter; adding the differential term, integral term, and proportional term of the switched PID controller, and then multiplying by the gain coefficient to obtain the output value.

[0016] Furthermore, the method further includes: determining the duration threshold based on the control error; the duration threshold is positively correlated with the absolute value of the control error, and the control error is obtained by subtracting the measured value from the target value of the controlled object.

[0017] Furthermore, the calculation expression for the duration threshold is:

[0018]

[0019] In the formula, For continuous threshold, For the preset minimum length, To control error, These are the preset system parameters.

[0020] Furthermore, the switching condition also includes: the absolute value of the rate of change observer is less than a first set value; the rate of change observer represents the current rate of change of temperature and humidity.

[0021] Furthermore, the switching conditions also include: the difference between the target value and the measured value of the controlled object exceeds a set range, the rate of change observer is less than a second set value, and the absolute value of the control error is greater than a third set value; the absolute value of the second set value is greater than the first set value.

[0022] In a second aspect, the present invention provides an energy-saving temperature and humidity test chamber, including a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the bidirectional PID controller flexible switching method of the energy-saving temperature and humidity test chamber described in the first aspect is implemented.

[0023] The beneficial effects of this invention are as follows: Compared with directly using the control components of the PID controller before switching as the control components of the PID controller after switching, by determining the relationship model based on the change of the target value of the controlled object, and then determining the control components of the PID controller after switching based on the relationship model, the instantaneous disturbances generated during switching can be avoided, and flexible switching of multiple PID controllers can be realized, thereby improving the stability of control and meeting the performance requirements under different operating conditions. Attached Figure Description

[0024] Figure 1 This is a flowchart of the flexible switching method of the bidirectional PID controller for the energy-saving temperature and humidity test chamber in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the PID controller switching based on the rate of change observer in an embodiment of the present invention;

[0026] Figure 3 This is a structural block diagram of the energy-saving temperature and humidity test chamber in an embodiment of the present invention. Detailed Implementation

[0027] 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, not all, of the embodiments of the present invention. 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.

[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] Figure 1 This is a flowchart of the flexible switching method of the bidirectional PID controller for the energy-saving temperature and humidity test chamber in an embodiment of the present invention.

[0030] In a first aspect, the present invention provides a flexible switching method for a bidirectional PID controller in an energy-saving temperature and humidity test chamber. The energy-saving temperature and humidity test chamber includes four PID controllers: a heating PID controller, a cooling PID controller, a humidification PID controller, and a dehumidification PID controller, used to control the heating, cooling, humidification, and dehumidification processes respectively. By using different PID controllers to control different processes, parameter coupling limitations can be avoided, and the control parameters of each PID controller can be independently optimized, achieving differentiated matching of dynamic characteristics. This meets the needs of different controllers and the different response characteristics of the controlled object, thereby improving the accuracy of control.

[0031] Specifically, such as Figure 1 As shown, the method of the present invention includes the following steps.

[0032] S101. If any preset switching condition is met, the switching type is determined based on the change in the target value of the controlled object.

[0033] In this embodiment, the switching types include setpoint switching, process switching, and online switching of linear following parameters, and the controlled object is the temperature or humidity of the energy-saving temperature and humidity test chamber.

[0034] Specifically, the PID controller is allowed to switch if any preset switching condition is met. Here, the switching refers to switching the type and / or parameters of the PID controller.

[0035] In this embodiment, the switching conditions include condition one, condition two, and condition three. Condition one is: the duration for which the output value of the PID controller before the switch is lower than the set lower limit parameter is greater than or equal to the duration threshold.

[0036] In one embodiment, a duration threshold can be determined based on the control error; wherein the duration threshold is positively correlated with the absolute value of the control error; the control error is obtained by subtracting the measured value from the target value of the controlled object. The measured value of the controlled object can be acquired through a temperature sensor and / or a humidity sensor, and the target value is input by the operator. Specifically, the expression for calculating the duration threshold is:

[0037]

[0038] In the formula, For continuous threshold, For the preset minimum length, To control error, The preset system parameters are constants.

[0039] During rapid temperature and humidity changes in an energy-saving temperature and humidity test chamber, the response lag of the chamber's actuators such as heaters and compressors, along with the humid and thermal inertia of the controlled object, leads to a significant phase delay in the system. Due to this phase delay, the instantaneous error reflects the past system state, not the current true system state. Therefore, when switching PID controllers in the nonlinear region, relying solely on the instantaneous error signal will trigger a dual-mode superposition effect, thereby compromising control stability.

[0040] In response, by allowing switching only when condition one is met, it is possible to avoid oscillations caused by relying solely on instantaneous error signals, and to offset control deviations caused by the accumulation of system inertia under error conditions, thereby improving the stability and compliance of control.

[0041] In one embodiment, condition two (steady-state switching) is: the absolute value of the rate of change observer is less than a first set value. Specifically, the rate of change observer... for:

[0042]

[0043] In the formula, For differential time, As the controlled object Regarding time The derivative of the controlled object is the rate of change of the controlled object.

[0044] The physical meaning of this rate of change observer can be approximated as a velocity signal, that is, representing the velocity / inertia of the current change in temperature and humidity. When condition two is met, it indicates that the inertia of the current change in temperature and humidity is small. By allowing switching, it can be ensured that the system enters the quasi-steady state stage, avoiding residual inertial disturbances, thereby improving the accuracy and stability of control.

[0045] In one embodiment, condition three (zero-crossing switching) is: the difference between the target value and the measured value of the controlled object exceeds the set range, the rate of change observer is less than the second set value, and the absolute value of the control error is greater than the third set value; wherein, the absolute value of the second set value is greater than the first set value, and the set range can be set to [-0.1, 0.1].

[0046] It should be noted that condition three is triggered only when condition two fails. When condition three is met, it indicates overshoot / over-adjustment, meaning the measured value of the controlled object is greater than the target value, and the inertial disturbance is relatively small. By allowing switching, the controlled object can stably reach or approach the target value, thus ensuring the accuracy and stability of the control. For example, in an energy-saving temperature and humidity test chamber during the heating process, with a target value of 80℃, the temperature continuously rises after heating. When the measured value reaches 81.5℃, the rate of change observer... It is a negative value. When this negative value is less than the second set value and the absolute value of the control error is greater than the third set value, it indicates that the overshoot is too large. At this time, it is allowed to switch the heating PID controller to the cooling PID controller so that the controlled object can reach the target value.

[0047] Specifically, the operating condition analysis of the rate of change observer is shown in Table 1, and the switching process is as follows: Figure 2 As shown, Figure 2 The dead zone is the interval in which the output values ​​of both the heating PID controller and the cooling PID controller are 0. It generally occurs when the switching conditions are not met.

[0048] Table 1

[0049]

[0050] By specifying that switching is only allowed when switching conditions are met, dynamic delay compensation for control inertia can be achieved, avoiding the superposition effect of dual modes, thereby improving the stability and accuracy of control.

[0051] Furthermore, if the target value undergoes a step change, the determined switching type is a fixed-point switching; if the target value remains constant, the determined switching type is a process switching; if the target value changes linearly, for example at a rate of 5℃ / min, the determined switching type is a linear follower parameter online switching.

[0052] In one embodiment, a step transition can be determined based on whether the absolute value of the difference between the new target value and the original target value is greater than a switching threshold. For example, if the new target value is 80°C and the original target value is 40°C, and the absolute value of the difference between the two is greater than the switching threshold of 30°C, then a step transition of the target value is determined.

[0053] S102. Match the corresponding relational model according to the switching type to obtain the control components of the PID controller after switching.

[0054] In this embodiment, the relational model is used to determine the control components based on the input data. The control components include the differential filter's accumulated value, the integral term, and the proportional term; the input data includes the target value and measured value of the controlled object.

[0055] In one embodiment, different switching types typically correspond to different performance requirements, as shown in Table 2.

[0056] Table 2

[0057]

[0058] Since the PID controller after the switch was not started before the switch, the integral and derivative terms cannot be clearly defined. If the integral and derivative terms of the PID controller before the switch are directly used as the integral and derivative terms of the PID controller after the switch, the different parameters and state values ​​used by different PID controllers will lead to control fluctuations, thereby reducing the stability of the control. Furthermore, direct use cannot meet different performance requirements.

[0059] Therefore, different relational models need to be matched according to different switching types to ensure that the output value of the PID controller after the switch can meet different performance requirements, while ensuring control stability. Specifically, if the switching type is setpoint to point switching, the matched relational model is as follows:

[0060]

[0061] In the formula, Let be the accumulated value of the differential filter of the PID controller after switching at time k. Let k be the integral term of the PID controller after the switch. Let k be the proportional term of the PID controller after switching. Let k be the target value of the controlled object at time k. Let k-1 be the target value of the controlled object. For differential time, The derivative term of the PID controller before the switching at time k-1 is... Let k be the measured value of the controlled object at time k. The measured value of the controlled object at time k-1 is... For the weight of the proportional term, These are the window parameters for the differential filter.

[0062] Because the calculation of the accumulated value of the differential filter incorporates the differential term of the PID controller before the switch, the differential term of the PID controller before the switch is flexibly transferred to the PID controller after the switch, avoiding instantaneous disturbances and thus achieving flexible switching of the control process. Furthermore, since the difference between the target value and the measured value before the switch is relatively small, i.e. The relatively small value ensures that the sum of the integral and proportional terms is sufficiently large, thereby guaranteeing a sufficiently large output value for the switched PID controller. This results in a rapid control response; that is, the larger the output value, the stronger the control and the faster the response. Therefore, calculating the control components of the switched PID controller using the above relationship model allows for the fastest possible attainment of the new target value while maintaining stability. Thus, this not only achieves flexible switching of the PID controller but also meets the user's requirement for rapid response.

[0063] For example, suppose an energy-saving temperature and humidity test chamber is maintained at a stable temperature of 30°C by a heating PID controller. If the operator changes the target temperature to -40°C based on actual needs, the system will switch to a cooling PID controller to achieve the target temperature. At this point, the output value of the cooling PID controller needs to be calculated. Since the cooling PID controller was not started before the switch, its output value requires specifying the proportional, derivative, and integral terms. Because the proportional term is known, while the derivative and integral terms are unknown, they need to be determined. If the derivative and integral terms calculated by the heating PID controller before the switch are directly used as the derivative and integral terms of the cooling PID controller, the different parameter sets and state values ​​used by the cooling and heating PID controllers will lead to unstable temperature control, potentially causing oscillations, and failing to meet the requirement for rapid response. To address this, the differential filter accumulation value and integral term can be determined using the aforementioned relationship model corresponding to the setpoint switching. Then, the derivative term can be calculated based on the differential filter accumulation value, ultimately ensuring that the output value of the cooling PID controller meets the requirements for rapid response and flexible switching. The method of calculating the differential term based on the accumulated value of the differential filter is an existing technique, so it will not be elaborated here.

[0064] Furthermore, if the switching type is process switching, then the matching relational model is:

[0065]

[0066] In the formula, Let be the accumulated value of the differential filter of the PID controller after switching at time k. Let k be the integral term of the PID controller after the switch. Let k be the proportional term of the PID controller after switching. Let k be the measured value of the controlled object at time k. Let k be the target value of the controlled object at time k. For differential time, This is the gain coefficient. The derivative term of the PID controller before the switching at time k-1 is... For the weight of the proportional term, These are the window parameters of the differential filter. , , These are all parameters of the switched PID controller, which can be set manually based on experience.

[0067] Similarly, through the relational model corresponding to process switching, it can be seen that the calculation of the cumulative value of the differential filter incorporates the differential term of the PID controller before switching, thus ensuring the smoothness of switching and the stability of control. Since the calculation of the integral term incorporates the proportional term of the PID controller after switching, the sum of the integral term and the proportional term will be relatively small, and the differential term will also be relatively small, ultimately ensuring that the output value of the PID controller after switching is small, thus avoiding control abrupt changes and improving control stability.

[0068] For example, suppose an energy-saving temperature and humidity test chamber is stably maintained at -40℃, controlled by a refrigeration PID controller. If the operator changes the target value to -10℃ based on actual needs, the refrigeration PID controller will switch to a heating PID controller to achieve the target value. During the temperature rise, the output value of the heating PID controller will gradually decrease from its initial value to 0%, for example, from 90% to 0%. This decrease to 0% is because the final target value is maintained by the refrigeration PID controller. Furthermore, since the switching type is a setpoint-to-point switching, the calculation of the initial value is explained in the section on setpoint-to-point switching above, and will not be repeated here.

[0069] When the temperature rises to -9℃, the heating PID controller has dropped to 0%. If the preset switching conditions are met, it will switch to the cooling PID controller. It should be noted that when the switching conditions are met, it indicates that the derivative term is relatively small. At this time, since the sum of the integral and proportional terms is also small, the final calculated output value of the cooling PID controller is close to 0% or the set lower limit of output, and it is gentle. This achieves a smooth transition in the control process and improves the stability and accuracy of the control.

[0070] If the switching type is linear following parameter online switching, then the matching relational model is:

[0071]

[0072] In the formula, Let be the accumulated value of the differential filter of the PID controller at time k. Let k be the integral term of the PID controller at time k. The proportional term of the PID controller at time k. Let k be the target value of the controlled object at time k. Let k be the measured value of the controlled object at time k. For the new differential time, For the new gain coefficient, For the new differential filter window parameters, The derivative term of the PID controller at time k-1 is... For the new proportional term weights, The output value of the PID controller at time k-1. This is the current output limit of the PID controller.

[0073] In the high-precision control process of energy-saving temperature and humidity test chambers, the PID controller parameters are not static. Due to the significant nonlinear thermodynamic characteristics exhibited by the controlled object over a wide temperature range—namely, increased heat capacity in the low-temperature region and enhanced radiative heat transfer in the high-temperature region—it is necessary to divide the parameters into multiple sets according to different temperature and humidity ranges to achieve dynamic characteristic matching and control performance optimization under various operating conditions. When executing a linear temperature change program, i.e., the target value changes linearly, for example, updating the target value at a rate of 10℃ / min, the target value crosses the parameter group boundary over time, for example, from the parameter group corresponding to 20~30℃ to the parameter group corresponding to 30~40℃. If the parameters are switched directly at this time, a sudden change in control gain or differential parameter will cause a step disturbance in the control quantity (i.e., the output value of the PID controller), thereby causing oscillation in the control process.

[0074] To eliminate instantaneous disturbances caused by linear changes in the target value, the control components calculated using the aforementioned relational model ensure the continuity of the control quantity during switching, thereby ensuring the stability and accuracy of the control. Specifically, the aforementioned relational model maintains the continuity of the control quantity by incorporating the calculated proportional and derivative terms into the integral term calculation. Simultaneously, since the integral term integrates the derivative term state, it ensures consistent dynamic response, ultimately achieving a smooth, disturbance-free transition of the parameter set.

[0075] It should be noted that if the switching type is linear follower parameter online switching, it may only change the parameters of the PID controller, not the type of PID controller. For example, when heating from 30℃ to 60℃, the entire process is controlled by the heating PID controller. During the heating process, different parameters are switched according to different temperature and humidity ranges, and the current output value of the heating PID controller is determined based on the new parameters.

[0076] S103. Calculate the output value of the PID controller after switching based on the control components.

[0077] Specifically, the differential term is calculated based on the accumulated value of the differential filter of the switched PID controller. Then, the differential, integral, and proportional terms of the switched PID controller are added together, and multiplied by the gain coefficient to obtain the output value of the switched PID controller. The specific expression for calculating the output value is as follows:

[0078]

[0079] In the formula, Let k be the output value of the PID controller at time k. Let k be the derivative term of the PID controller at time k. The proportional term of the PID controller at time k. Let k be the integral term of the PID controller at time k. This is the gain coefficient.

[0080] By matching the corresponding relationship model according to the operating conditions of the control process, i.e., according to the switching type, the flexible switching of each PID controller is ensured, thereby improving the stability of the control.

[0081] Figure 3 This is a schematic diagram illustrating the structure of the energy-saving temperature and humidity test chamber according to this embodiment.

[0082] In a second aspect, the present invention also provides an energy-saving temperature and humidity test chamber. For example... Figure 3 As shown, the energy-saving temperature and humidity test chamber includes a processor and a memory. The memory stores computer program instructions. When the computer program instructions are executed by the processor, the bidirectional PID controller flexible switching method of the energy-saving temperature and humidity test chamber described in the first aspect of the present invention is implemented.

[0083] The energy-saving temperature and humidity test chamber also includes other components well known to those skilled in the art, such as communication interfaces. Their settings and functions are known in the art and will not be described in detail here.

[0084] In this invention, the aforementioned memory can be any tangible medium containing or storing a program that can be used or combined with an instruction execution system, apparatus, or device. For example, a computer-readable storage medium can be any suitable magnetic or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc., or any other medium that can be used to store desired information and can be accessed by an application, module, or both. Any such computer storage medium can be part of a device or accessible to or connected to a device. Any application or module described in this invention can be implemented using computer-readable / executable instructions that can be stored or otherwise maintained by such a computer-readable medium.

[0085] In the description of this specification, "multiple" means at least two, such as two, three or more, unless otherwise explicitly specified. Furthermore, the steps described above are for clarity only; in implementation, they can be combined into one step or some steps can be broken down into multiple steps, as long as they include the same logical relationships.

[0086] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.

Claims

1. A flexible switching method for a bidirectional PID controller in an energy-saving temperature and humidity test chamber, applied to an energy-saving temperature and humidity test chamber that uses different PID controllers to control the heating, cooling, humidification, and dehumidification processes respectively, characterized in that, include: If any preset switching condition is met, the switching type is determined based on the change in the target value of the controlled object; The switching conditions include: the duration for which the output value of the PID controller before switching is lower than the set lower limit parameter is greater than or equal to the duration threshold; the switching types include setpoint switching, process switching, and online switching of linear follower parameters; The corresponding relational model is matched according to the switching type to obtain the control components of the PID controller after switching; the relational model is used to determine the control components based on the input data, the input data including the target value and the measured value of the controlled object, and the control components including the proportional term, the integral term and the cumulative value of the differential filter, wherein the proportional term is determined by the target value and the measured value; Based on the switching type, the corresponding relational model is matched to obtain the control components of the PID controller after the switch, including: If the switching type is a fixed-value to point-based switching, then the matching relational model is: If the switching type is process switching, then the matching relational model is: If the switching type is linear following parameter online switching, then the matching relational model is: In the formula, Let be the accumulated value of the differential filter of the PID controller after switching at time k. Let k be the integral term of the PID controller after the switch. Let k be the proportional term of the PID controller after switching. Let k be the measured value of the controlled object at time k. The measured value of the controlled object at time k-1 is... Let k be the target value of the controlled object at time k. Let k-1 be the target value of the controlled object. For differential time, This is the gain coefficient. The derivative term of the PID controller before the switching at time k-1 is... For the weight of the proportional term, These are the window parameters of the differential filter. For the new proportional term weights, For the new gain coefficient, For the new differential time, For the new differential filter window parameters, This is the current output limit of the PID controller. The derivative term of the PID controller at time k-1 is... This represents the output value of the PID controller at time k-1. The output value of the PID controller after switching is calculated based on the control components.

2. The flexible switching method for the bidirectional PID controller of the energy-saving temperature and humidity test chamber according to claim 1, characterized in that, The switching type is determined based on the changes in the target value of the controlled object, including: If the target value undergoes a step transformation, the determined switching type is a fixed-value to point-to-point switching. If the target value is constant, the determined switching type is process switching; If the target value changes linearly, the determined switching type is linear following parameter online switching.

3. The flexible switching method of the bidirectional PID controller for the energy-saving temperature and humidity test chamber according to claim 1, characterized in that, The output value of the PID controller after switching is calculated based on the control components, including: Calculate the differential term of the PID controller after switching based on the accumulated value of the differential filter; The output value is obtained by adding the derivative, integral, and proportional terms of the switched PID controller and then multiplying the sum by the gain coefficient.

4. The bidirectional PID controller flexible switching method for the energy-saving temperature and humidity test chamber according to claim 1, characterized in that, Also includes: The duration threshold is determined based on the control error; The sustained threshold is positively correlated with the absolute value of the control error, which is obtained by subtracting the measured value from the target value of the controlled object.

5. The bidirectional PID controller flexible switching method for the energy-saving temperature and humidity test chamber according to claim 4, characterized in that, The calculation expression for the duration threshold is: In the formula, For continuous threshold, For the preset minimum length, To control error, These are the preset system parameters.

6. The flexible switching method for the bidirectional PID controller of the energy-saving temperature and humidity test chamber according to claim 1, characterized in that, The switching conditions also include: the absolute value of the rate of change observer is less than a first set value; the rate of change observer represents the current rate of change of temperature and humidity.

7. The flexible switching method for the bidirectional PID controller of the energy-saving temperature and humidity test chamber according to claim 6, characterized in that, The switching conditions also include: the difference between the target value and the measured value of the controlled object exceeds the set range, the rate of change observer is less than the second set value, and the absolute value of the control error is greater than the third set value; the absolute value of the second set value is greater than the first set value.

8. An energy-saving temperature and humidity test chamber, characterized in that, It includes a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the bidirectional PID controller flexible switching method of the energy-saving temperature and humidity test chamber according to any one of claims 1-7 is implemented.

Images