A heating control method and system for arrayed electric heating tape

Abstract

This invention relates to a heating control method and system for arrayed electric heating cables. The method includes: an array construction and control circuit setup step, in which the heating unit array is fixed to a carrier and configured with a one-to-one voltage regulation link; a temperature value acquisition step, in which the resistance of the heating unit is calculated by collecting the voltage and current of the heating unit, and the real-time temperature of the heating unit is obtained by combining the resistance-temperature reference curve; a compensation voltage calculation step, in which a model is established based on the temperature difference between different zones of the carrier, the temperature of the heating unit, and multi-dimensional influencing parameters to calculate the compensation voltage; and a temperature control step, in which the heating power is adjusted by superimposing the compensation voltage and the real-time voltage to achieve precise temperature control of different zones of the carrier. The system includes a main control module, a power drive and control module, a sensor module, and a power supply module, with each module working together to complete the control logic. This invention improves the accuracy of temperature control of different zones of the carrier and the reliability of the system, and is adaptable to various carrier shapes.

Description

Technical Field

[0001] This invention relates to the field of temperature control and regulation system technology, specifically to a heating control method and system for arrayed electric heating tapes. Background Technology

[0002] Currently, in many electric heat tracing applications, such as pipeline antifreeze and tank insulation, control systems based on mechanical temperature controllers or contactors are still widely used. This system senses the temperature of the object being heated or the environment through one or more mechanical temperature sensors. When the temperature falls below a set lower limit, the mechanical contacts within the temperature controller close, connecting the circuit and initiating heating with the electric heat tracing tape. When the temperature reaches the set upper limit, the contacts mechanically open, stopping heating. This technology has some drawbacks and problems in practical applications. Mechanical temperature controllers suffer from low control accuracy and significant energy waste; control systems based on mechanical temperature controllers or contactors have limited control functions and cannot achieve intelligent management; the systems typically operate in isolation, lacking remote communication, fault alarm functions, and centralized monitoring and data recording capabilities; furthermore, mechanical contacts are prone to generating electrical sparks, posing a safety hazard.

[0003] Furthermore, a self-regulating heating cable, also known as an electric heating cable, is proposed, which utilizes its ability to automatically adjust its heating power according to changes in ambient temperature. Its core component is a PTC polymer material as the heating element. When the ambient temperature is low, the microstructure of the PTC material shrinks, forming more conductive paths, reducing resistance and increasing heating power. When the ambient temperature rises, the PTC material expands, reducing conductive paths, increasing resistance, and automatically decreasing heating power.

[0004] However, the electric heating tape mentioned above still has problems in application. Because the adjustment function of the electric heating tape is local and passive, it cannot receive instructions from the central control system, nor can it achieve global and precise temperature control according to the needs of the entire process, such as different areas of the pipe section needing to meet different temperature requirements. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an arrayed electric heating cable heating control method and system, in order to solve the problems of low temperature control accuracy, disconnection of carrier temperature control, poor adaptability to working conditions, and insufficient reliability of the control system in the current electric heating cable heating control technology.

[0006] This invention provides a heating control method for arrayed electric heating tapes, characterized in that the control method specifically includes:

[0007] The control circuit establishment step involves dividing the carrier into several heating areas, and setting multiple independent heating units in each heating area, with a power regulation unit configured for each heating unit to form a one-to-one control link.

[0008] This step enables the carrier to be arranged in zones and controlled in a distributed manner, thereby avoiding the inability to locally regulate the traditional whole-section heat tracing.

[0009] The temperature value acquisition step involves acquiring the real-time voltage and real-time current of each heating unit to obtain the real-time resistance value of each heating unit. The real-time resistance value is then used as an index to search for a matching real-time heating temperature value in a preset resistance-temperature baseline. The real-time heating temperature value represents the estimated self-temperature value of the heating unit at the current moment.

[0010] This step obtains the real-time heating temperature value of the heating unit by establishing a resistance-temperature baseline, eliminating the need to install a temperature sensor, reducing costs, and directly obtaining the temperature of the heating unit itself.

[0011] The compensation calculation step involves obtaining the measured temperature value of each heating zone and comparing it with the preset temperature value of each heating zone to obtain the temperature deviation of each heating zone. The temperature deviation is then substituted into the PID algorithm to obtain the power control amount corresponding to each heating zone.

[0012] This step uses a mature PID control algorithm to take the temperature deviation between the measured temperature of the area and the preset temperature as input to obtain the total power regulation of the heating area.

[0013] The temperature control step involves obtaining the corresponding compensation power for each heating unit in each heating zone according to the allocation strategy, and inputting it to the corresponding heating unit. The temperature value acquisition step, compensation calculation step, and temperature control step are repeated until the temperature deviation is less than the preset temperature difference threshold, so that the measured temperature value of the zone is close to the corresponding preset temperature value.

[0014] This step distributes the total power control amount of the region to each heating unit according to the allocation strategy, making the control more precise, and repeats the process until the temperature deviation is less than the threshold.

[0015] Furthermore, the allocation strategy is specifically as follows:

[0016] Obtain the relative position of each heating unit in the target heating area with respect to the target heating area and the relative position of the target heating area with respect to the carrier.

[0017] The system acquires the real-time heating temperature value of each heating unit in the target heating area, as well as the measured temperature value of the target heating area and the measured temperature value of the adjacent heating areas.

[0018] Based on the relative position of each heating unit in the target heating area, the real-time heating temperature value, and the measured temperature value of the heating area adjacent to the target heating area, the power regulation allocation weight value corresponding to each heating unit in the target heating area is calculated, and the compensation power of each heating unit is obtained based on the power regulation allocation weight value.

[0019] The allocation strategy comprehensively considers the relative position of the heating unit within the region when calculating the weight of each heating unit to compensate for the difference between being located at the edge or the center. The heating unit heats the temperature value in real time to achieve on-demand compensation. It also considers the thermal coupling between the temperatures of adjacent heating areas, making the control more realistic and more accurate.

[0020] Furthermore, the temperature value acquisition step is configured with a heating unit self-temperature correction sub-strategy. After the real-time heating temperature value is found from the resistance-temperature baseline, the heating unit self-temperature correction sub-strategy is executed, specifically as follows:

[0021] Record the cumulative power-on time for each heating unit, and calculate the duration aging correction amount based on the cumulative power-on time;

[0022] The real-time heating temperature value of the heating unit is obtained by matching the resistance-temperature baseline. The temperature difference between the heating unit and the adjacent heating unit is calculated based on the real-time heating temperature value of the heating unit and the corresponding adjacent heating unit. The thermal coupling correction amount is then calculated using the preset thermal coupling coefficient.

[0023] The temperature value obtained by summing the real-time heating temperature value of the heating unit with the time aging correction amount and the thermal coupling correction amount is used as the corrected real-time heating temperature value of the heating unit.

[0024] The correction sub-strategy aims to obtain a more accurate real-time heating temperature value for the heating unit. It requires compensation for aging caused by long-term use and correction for the thermal coupling effect between adjacent heating units, so as to improve the accuracy of the real-time heating temperature value and provide a reliable basis for weight allocation.

[0025] Furthermore, the adjacent heating units include adjacent heating units within the same heating area of ​​the heating unit, and cross-regional adjacent heating units in other heating areas that are adjacent to the heating area of ​​the heating unit.

[0026] When considering adjacent heating units, it is necessary to consider not only heating units within the same heating area, but also heating units across different areas, so as to fully cover all adjacent units that have a thermal impact on the target heating unit.

[0027] Furthermore, the steps for establishing the resistance-temperature baseline are as follows:

[0028] In the simulated constant temperature chamber, by adjusting the power of the input heating unit and the temperature of the constant temperature chamber, and keeping the current working conditions unchanged and letting it stand still for a period of time, the temperature and resistance values ​​are collected. When it is determined that the temperature change rate and resistance change rate of the heating unit are both lower than the threshold, the current moment is a stable state and the resistance and temperature values ​​of the heating unit are recorded at this time.

[0029] The recorded resistance values, temperature values, and ambient temperature values ​​are combined into a set of data, and multiple sets of data are combined into a dataset.

[0030] By establishing a fitting relationship with the dataset, the resistance-temperature baseline of the heating unit is obtained.

[0031] Through constant temperature chamber experiments, an accurate, reliable resistance-temperature mapping relationship with environmental temperature compensation was established.

[0032] Furthermore, in the repeated temperature value acquisition step, after inputting compensation power to each heating unit in the heating area, the power output remains unchanged and is continuously stabilized for a preset time before the regional temperature value of the heating area is acquired, and the regional temperature value that meets the stability condition is determined as the actual measured temperature value of the region.

[0033] The stability condition is specifically the rate of temperature change obtained by the ratio of the temperature difference between the current temperature value and the previous temperature value to time, and the rate of temperature change is lower than the change threshold.

[0034] After each application of compensation power to the heating unit, a preset stabilization time is waited for, and stability is determined by the temperature change rate being lower than a threshold. Then, the regional temperature is collected as feedback to ensure that the input temperature difference is a stable temperature difference and to avoid frequent adjustments caused by transient temperature fluctuations.

[0035] Furthermore, the temperature control step includes a fault diagnosis strategy, specifically comprising:

[0036] The number of times the continuous compensation step is executed in each heating zone is accumulated and compared with the set number threshold. If the number of times exceeds the threshold and the temperature deviation is still greater than the temperature difference threshold, it is determined that there is an abnormality in the heating unit under that heating zone, and a fault alarm is triggered.

[0037] The system obtains the measured temperature of the heating zone after two consecutive compensation adjustments, calculates the absolute value of the temperature change between the two consecutive measured temperatures, and compares it with the set change threshold. If the change is less than the change threshold and the temperature deviation is still greater than the temperature difference threshold, it is determined that there is an abnormality in the heating unit in the heating zone, and a fault alarm is triggered.

[0038] If the number of consecutive compensations is too high and the temperature still does not meet the standard, or if the temperature change is very small after two consecutive compensations but the stability still does not meet the standard, it indicates that there is an abnormality in the heating unit, thus enabling timely detection of abnormalities in the heating unit during the closed-loop regulation process.

[0039] Furthermore, the temperature control step also includes a compensation power adjustment strategy, specifically:

[0040] The total input power is obtained by summing the compensation power of each heating unit with the current actual input power. The total input power is then compared with the rated maximum power. If the total input power exceeds the rated maximum power, the rated maximum power is set as the input power of the heating unit.

[0041] Compare the total input power with the rated minimum power; if the total input power is lower, then the rated minimum power is set as the input power of the heating unit.

[0042] The compensation power adjustment strategy ensures the upper and lower limits of the input power of each heating unit, avoiding damage to the heating unit due to excessive power or waste of energy due to insufficient power.

[0043] The present invention also provides a system applicable to the above-described arrayed electric heating tape heating control method, the system comprising:

[0044] The main control module stores the control link addresses of all heating units and the resistance-temperature baseline, and is used to run compensation calculation steps and execute control logic tasks.

[0045] The power drive and control module includes a power regulation unit that regulates the power of each heating unit. The power regulation unit is used to receive control signals from the main control module to adjust the conduction of the power regulation unit. The power regulation unit is used to regulate the power input to the heating unit.

[0046] The temperature acquisition module is used to collect the measured temperature values ​​of each heating zone.

[0047] The power supply module is used to provide power to each module.

[0048] The wireless communication module is used for data interaction between the main control module and the remote monitoring platform.

[0049] The human-computer interaction module is used to display on-site working parameter information and allows local parameter setting and operation;

[0050] The remote monitoring platform is used to display the real-time operating parameters of each heating unit and is responsible for alarm management and remote control.

[0051] Furthermore, the heating unit is an electric heating tape.

[0052] Technical effects of the present invention:

[0053] This invention achieves differentiated and precise temperature control of multiple regions of the carrier by dividing the carrier into sections and using an array of multiple heating units for independent control. By acquiring the temperature difference of each heating area and relying on regional PID adjustment and fine power distribution, it significantly improves temperature uniformity and control accuracy, and solves the problems of large local temperature differences and substandard carrier temperature control caused by traditional overall control.

[0054] This invention achieves more accurate real-time heating temperature values ​​of the heating unit by setting a temperature correction sub-strategy; and limits the input power range by designing a fault judgment strategy and an input power adjustment strategy, thereby avoiding system risks caused by compensation failure or heating unit failure and improving long-term operational reliability. Attached Figure Description

[0055] Figure 1 This is a schematic flowchart of a heating control method for an arrayed electric heating cable according to the present invention.

[0056] Figure 2 This is a block diagram of the control circuit for a single electric heating cable in an arrayed electric heating cable control system of the present invention. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0059] 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. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0060] This invention proposes an arrayed electric heating cable heating control system, which is installed in an intelligent control box and includes:

[0061] The main control module stores the control link addresses of all heating units and the resistance-temperature reference lines of the heating units. It can use the STM32F103 series ARM Cortex-M3 core microcontroller U3, which contains a calculation model for calculating power values ​​based on temperature difference data, PID controller proportional parameters, PID controller integral parameters, and PID controller derivative parameters. This enables it to run the compensation calculation steps to calculate the power regulation of each heating zone, process data, manage communication, and execute control logic tasks.

[0062] The power drive and control module includes a power regulation unit that regulates the power of each heating unit. The power regulation unit is used to receive control signals from the main control module to adjust the conduction of the power regulation unit, and each power regulation unit is used to regulate the power input to the corresponding heating unit.

[0063] In one embodiment of the present invention, the power regulation unit employs a zero-crossing optocoupler-type bidirectional thyristor, which has a built-in zero-crossing detection function to reduce electromagnetic interference when the thyristor is turned on. The input terminal of the optocoupler-type bidirectional thyristor is connected to the PWM_P output pin of the main control module U3 through a current-limiting resistor. When the main control module U3 outputs a trigger signal, the optocoupler-type bidirectional thyristor turns on, thereby triggering the high-power thyristor to turn on near the zero-crossing point of the AC current. By changing the conduction angle of each half-wave cycle, the effective voltage and power input to the heating unit are adjusted.

[0064] The temperature acquisition module includes temperature sensors that collect the measured temperature values ​​of each heating zone. The temperature sensors can use PT100 platinum resistance temperature sensors as probes, which are installed on each zone of the carrier. They are also equipped with high-precision ADC digital converter chips and their peripheral circuits to convert the resistance signal of the PT100 platinum resistance temperature sensor into a high-precision digital temperature value and transmit it to the main control module U3.

[0065] The power supply module uses a switching power supply with an input of 220V AC and an output of +12V DC. The +12V DC is converted to +5V DC through a DC-DC circuit to power the communication module. The +5V DC is converted to +3.3V through an LD1117-3.3 LDO voltage regulator chip to power the main control module U3, temperature acquisition module and other core circuits.

[0066] The wireless communication module adopts a dual-mode LoRa+4G CAT.1 module. The LoRa part uses E22-400T30D module from EBITA, which is connected to the main control module U3 via UART and is used to communicate with the LoRa gateway in the factory area to achieve low-power data aggregation. The 4G part uses NC_ML307R module from Yike Communication, which is connected to the main control module U3 via UART and serves as the primary channel to directly upload data to the cloud platform.

[0067] The human-machine interaction module is specifically an OLED display screen installed on the enclosure. It communicates with the main control module U3 via I2C and is used for displaying on-site working parameter information. It can also be used for human-machine interaction via Bluetooth using a handheld device to allow local parameter setting and operation. The handheld device is a portable device for industrial equipment control, which usually interacts with the operator through buttons, knobs or touch screens, or establishes a wireless connection with the controlled equipment via Bluetooth to achieve remote control.

[0068] The remote monitoring platform adopts a B / S architecture, is deployed on a cloud server, uses languages ​​such as Java or Python to develop the backend, uses MySQL as the database, and uses the Vue.js framework for the frontend. This remote monitoring platform receives data from 4G modules and LoRa gateways via the MQTT protocol.

[0069] In one embodiment of the present invention, the heating unit adopts an electric heating tape. In practical applications, the area is first divided according to the temperature control requirements of the carrier, and the boundaries between adjacent heating areas are clear, without overlap or omission, and the entire surface to be heated is fully covered. Each heating area has independent temperature control, independent power output and independent temperature acquisition.

[0070] Multiple electric heating cables are arranged in each heating zone, and these electric heating cables need to be standardized. Specifically, the electric heating cables in all heating zones have the same length, shape and size, and the same nominal power and resistance value. In addition, the electric heating cables in all heating zones are laid out in the same way, and the laying spacing between electric heating cables in the same zone and between electric heating cables across zones are consistent. This ensures that the control algorithm, the baseline and weight allocation of the heating units are universal for all heating zones.

[0071] It is also necessary to configure an independent control link for each electric heating tape in each heating zone to realize independent voltage sampling, current sampling, and power regulation output for each heating unit.

[0072] In one embodiment of the present invention, multiple heating zones are divided on the carrier, and multiple heating units are installed in each heating zone. During the installation process, the positions of each heating zone relative to the carrier, the adjacency relationships between heating zones, the position of each heating unit relative to its respective heating zone, and the adjacency relationships between heating units are recorded and stored in the control system. Specifically:

[0073] After completing the division of the heating area of ​​the carrier and the installation and deployment of each heating unit, during the system installation and configuration phase, the position information of each heating area relative to the carrier, the adjacency relationship between each heating area, the position information of each heating unit relative to its heating area (including center position, internal position, and edge position), and the adjacency relationship between each heating unit and other heating units (including adjacency within the same area and adjacency across areas) are entered and stored in the control system. It is also necessary to store the spacing between adjacent heating units within the same area and the spacing between adjacent heating units across areas in the control system.

[0074] Because the position of each heating zone and each heating unit remains unchanged after installation, there is no need to detect or identify the position again during subsequent temperature control. The stored position information can be directly called to determine the relative position and adjacent relationship of each heating unit.

[0075] Based on the aforementioned arrayed electric heating cable heating control system, this invention also proposes a heating control method, including a control circuit establishment step, a temperature acquisition step, a compensation calculation step, and a temperature regulation step, to achieve precise temperature control, such as... Figure 1 As shown, specifically:

[0076] The control circuit establishment step involves dividing the carrier into several heating areas, and setting multiple independent heating units in each heating area, with a power regulation unit configured for each heating unit to form a one-to-one control link.

[0077] This step is the foundational step in the arrayed electric heating tape heating control method. Dividing the heating into multiple heating zones is to achieve distributed and precise temperature control of the carrier, overcoming the technical shortcomings of traditional whole-section heating that cannot be locally adjusted. Here, a heating zone refers to several independent and clearly defined temperature control units formed by dividing the entire surface to be heated of the carrier according to the carrier's temperature control requirements, structural form, heat dissipation conditions, and actual application conditions. Each heating zone has independent temperature acquisition and power regulation capabilities. Each heating zone is equipped with heating units, which are the smallest independent heating elements that constitute the arrayed heating structure. In this invention, the heating units use electric heating tape, specifically a self-limiting electric heating product using PTC polymer material as the heating element, which has the basic characteristic of adjusting its resistance value according to changes in ambient temperature.

[0078] For example, industrial pipelines need to be insulated and protected against freezing throughout their entire length. The total length is 100 meters. Based on the heat dissipation conditions of the environment where the pipeline is laid on site, it is divided into a heating zone every 10 meters along its length, for a total of 10 heating zones. The target insulation temperature of each heating zone is 5 degrees Celsius. The fixed supports of the pipeline serve as the natural boundary between each heating zone, ensuring that the boundaries are clear and relatively independent.

[0079] If it is a circular storage tank, it can be divided according to the combination of circumferential and radial directions. Taking a vertical liquid storage tank with a diameter of 5 meters and a height of 8 meters as an example, the tank is divided into a circumferential area every 90 degrees along the circumference and a radial area every 2 meters along the radial direction, forming a total of 16 heating areas. Each heating area is set with a corresponding target temperature according to the actual heat dissipation characteristics of the tank. The target temperature of the heating area at the bottom of the tank wall is set to 8 degrees Celsius, and the target temperature of the heating area at the top of the tank wall is set to 5 degrees Celsius, to ensure that the division matches the actual temperature control requirements.

[0080] Each independent heating unit is assigned a corresponding power control unit. This power control unit controls the input power to its corresponding heating unit, and each heating unit uniquely corresponds to one power control unit, forming a one-to-one control link. Furthermore, each heating unit is equipped with independent voltage and current acquisition channels, creating a dedicated control and data acquisition link from the main control module to the corresponding power control unit and then to the corresponding heating unit. This link features unidirectional signal transmission and independent data feedback, ensuring that the control and monitoring of each heating unit do not interfere with each other. (See attached diagram.) Figure 2 The control block diagram for a single heating unit is shown.

[0081] For example, if a single heating area has 8 heating units, then there are 8 corresponding power control units. The output of each power control unit is connected to the input of the heating unit, and the input is connected to the corresponding output signal pin of the main control module. The main control module calculates the power input to each heating unit and adjusts the output signal of the corresponding pin. After being input to the corresponding power control unit, the conduction angle of the power control unit is adjusted. Furthermore, the real-time voltage and current data of each heating unit are fed back to the main control module through a dedicated acquisition channel, without data interaction with other control links.

[0082] The temperature value acquisition step involves acquiring the real-time voltage and real-time current of each heating unit to obtain the real-time resistance value of each heating unit. Using the real-time resistance value as an index, the matching real-time heating temperature value is searched in the preset resistance-temperature baseline. The real-time heating temperature value represents the estimated self-temperature value of the heating unit at the current moment.

[0083] The first step is to establish a resistance-temperature baseline for the heating unit through calibration experiments. The establishment process is as follows:

[0084] In the simulated constant temperature chamber, by adjusting the power of the input heating unit and the temperature of the constant temperature chamber, and keeping the current working conditions unchanged and letting it stand still for a period of time, the temperature and resistance values ​​are collected. When it is determined that the temperature change rate and resistance change rate of the heating unit are both lower than the threshold, the current moment is a stable state and the resistance and temperature values ​​of the heating unit are recorded at this time.

[0085] Among them, the simulated constant temperature chamber refers to an experimental device that can simulate different ambient temperature conditions and has the ability to accurately control and maintain a constant temperature. This device can achieve precise temperature control within a set temperature range and the temperature fluctuation meets the experimental requirements.

[0086] In this calibration test, the electric heating cable with the smallest independent heating element is used as the object, and the set ambient temperature of the constant temperature chamber and the electrical power input to the heating unit are used as the test conditions. After each change of the test conditions, the current test conditions must be kept unchanged so that the heating unit can exchange heat under the test conditions until its own temperature and the ambient temperature reach thermal equilibrium. This ensures that the temperature and resistance values ​​obtained are the actual values ​​of the heating unit after it has reached a stable thermal equilibrium state.

[0087] To determine whether the heating unit has reached a stable thermal equilibrium state, threshold values ​​for the rate of temperature change and the rate of resistance change are set as criteria. The rate of temperature change refers to the amount of temperature change of the heating unit per unit time, which reflects the trend of temperature change over time. The rate of resistance change refers to the amount of resistance change of the heating unit per unit time, which reflects the trend of resistance change over time. When both the actual rate of temperature change and the rate of resistance change of the heating unit are lower than the set threshold values, it is determined that the heating unit has reached a stable state.

[0088] The recorded resistance values, temperature values, and ambient temperature values ​​are combined into a set of data. Multiple sets of data form a dataset. Specifically, the dataset includes a collection of multiple sets of resistance values, temperature values, and corresponding ambient temperature values ​​recorded after calibration experiments on the heating unit under different experimental calibration conditions.

[0089] Subsequently, all data in the acquired dataset are sorted and filtered to remove abnormal data caused by experimental errors in order to ensure the accuracy and effectiveness of the dataset. Then, the least squares method can be used to perform curve fitting on the sorted dataset. The curve corresponding to the obtained fitting function is the resistance-temperature baseline of the heating unit. In the process of fitting and establishing the baseline, the inherent characteristic of the resistance adaptively adjusting with the ambient temperature is incorporated to obtain the resistance-temperature baseline of the heating unit after ambient temperature compensation.

[0090] The function corresponding to the baseline is Where R is the real-time resistance value of the heating unit, in ohms, representing the actual resistance of the heating unit at a certain temperature, which is the core detection value calculated by collecting real-time voltage and current; T is the real-time heating temperature value of the heating unit, in degrees Celsius, representing the estimated self-temperature of the heating unit at the current moment, which is obtained by looking up the baseline from the resistance value. The coefficient of the quadratic term has a dimension of ohms per degree Celsius squared. It is determined by the nonlinear temperature resistance characteristics of the heating unit material and is a proportionality coefficient obtained by fitting, reflecting the rate of change of resistance with the square of temperature. The coefficient of the first term, with dimensions in ohms per degree Celsius, is the proportionality coefficient obtained from the fitting, reflecting the rate of linear change of resistance with temperature. is a constant term with the dimension of ohms. The fitted reference constant represents the basic resistance value of the heating unit at a temperature of 0℃.

[0091] After obtaining the resistance-temperature baseline, the validation data that was not used in the fitting calculation in the dataset is selected and substituted into the fitting function to calculate the resistance value. The value is then compared with the actual measured resistance value. After obtaining the error, it is determined whether the error is within the experimental error range. Otherwise, the data in the dataset needs to be used to continue fitting and adjusting to ensure the accuracy of the fitted resistance-temperature baseline.

[0092] The temperature value acquisition step also includes a heating unit self-temperature correction sub-strategy. This sub-strategy is executed after the real-time heating temperature value is found from the resistance-temperature baseline. This sub-strategy eliminates the self-temperature error caused by the heating unit's aging and thermal coupling with adjacent units during actual operation through the superposition of multi-dimensional correction amounts, thereby improving the accuracy of temperature detection and ensuring reliable temperature data for subsequent power allocation and temperature control. Specifically:

[0093] The cumulative power-on time of each heating unit is recorded. Cumulative power-on time refers to the total power-on operating time of a single heating unit from its initial operation to the current moment. This time is continuously accumulated without interruption due to the start-up and shutdown of the heating unit. Because the long-term power-on operation of the heating unit causes slow changes in the physical properties of its internal PTC polymer heating material, resulting in temperature deviation, the aging correction amount is calculated using the cumulative power-on time. ;

[0094] Duration aging correction The calculation is based on the existing aging correction formula, and the duration of the aging correction has a negative correlation with the real-time heating temperature of the heating unit.

[0095] The real-time heating temperature value of the heating unit is obtained by matching the resistance-temperature baseline. The temperature difference between the heating unit and the adjacent heating unit is calculated based on the real-time heating temperature values ​​of the heating unit and the corresponding adjacent heating units. The adjacent heating unit refers to the unit that is physically adjacent to the target heating unit and exchanges heat through heat conduction and heat radiation. The adjacent heating unit includes adjacent heating units in the same heating area as the target heating unit and adjacent heating units in other heating areas that are adjacent to the target heating unit. That is, it includes adjacent heating units in the same area and adjacent heating units in other areas.

[0096] Because the target heating unit and its adjacent heating units have different temperatures, the temperature difference causes heat exchange between them, which in turn leads to a deviation in the estimation of the target heating unit's own temperature. Therefore, it is necessary to use a pre-set thermal coupling coefficient to calculate the thermal coupling correction amount for compensation. The thermal coupling coefficient is a coefficient that is pre-calibrated through experiments and is used to quantify the degree of thermal coupling between the target heating unit and a single adjacent heating unit. This coefficient is related to the physical spacing between the heating units, the laying method, and the thermal conductivity of the carrier. Different adjacent relationships correspond to different thermal coupling coefficients, and their values ​​range from 0 to 1.

[0097] The formula for calculating thermal coupling correction is as follows: ,in, This is a thermal coupling correction value, with dimensions in degrees Celsius, representing the compensation value for temperature estimation deviation caused by heat exchange between the target heating unit and adjacent heating units. The summation symbol represents the summation calculated over all adjacent heating units of the target heating unit, where m is the total number of adjacent heating units of the target heating unit, which is dimensionless. The thermal coupling coefficient between the target heating unit and the nth adjacent heating unit is dimensionless and ranges from 0 to 1. It is determined by experiments based on the spacing between the heating units and the thermal conductivity of the carrier. When the spacing and carrier are the same, a fixed value is taken. For example, it is 0.8 to 0.9 for adjacent units across the edge and 0.5 to 0.7 for adjacent units within the same area. The real-time heating temperature value of the nth adjacent heating unit is expressed in degrees Celsius. The original real-time heating temperature value of the target heating unit is found from the resistance-temperature baseline, in degrees Celsius.

[0098] Finally, the real-time heating temperature value of the heating unit is summed with the time-based aging correction and the thermal coupling correction to obtain the corrected real-time heating temperature value. The final formula for the corrected real-time heating temperature value is as follows: , This is the real-time heating temperature value after correction of the heating unit.

[0099] The compensation calculation step involves obtaining the measured temperature value of each heating zone and comparing it with the preset temperature value of each heating zone to obtain the temperature deviation of each heating zone. The temperature deviation is then substituted into the PID algorithm to obtain the power control amount corresponding to each heating zone.

[0100] Specifically, the measured temperature value of the aforementioned area refers to the actual temperature value accurately acquired by the temperature acquisition module when the heating area is in a thermal equilibrium stable state. The thermal equilibrium stable state means that after the main control module adjusts the input signal to the power control unit corresponding to each heating unit in the heating area, the power input must remain unchanged and the temperature value of the heating area must be acquired after a preset stable time. It is then determined whether the area temperature value meets the stability condition, that is, when the temperature change rate is lower than the change threshold, it is considered to be in a thermal equilibrium stable state. The acquired measured temperature value of the area is a true reflection of the overall temperature state of the heating area and is also the actual value basis for temperature deviation calculation. The preset temperature value refers to the target temperature value pre-set for each heating area according to the actual temperature control requirements of the carrier. This value is entered into the main control module during the system configuration stage and can be adjusted locally or remotely according to the actual working conditions. It is the target value basis for temperature deviation calculation.

[0101] The PID algorithm used is a mature existing calculation method. It is a classic closed-loop control algorithm composed of proportional, integral, and derivative links. This algorithm performs proportional, integral, and derivative operations on the input temperature deviation signal and outputs a power control quantity that can eliminate the deviation.

[0102] The main control module executes a PID control algorithm at a fixed period, which can be 1 second. Specifically:

[0103] ,

[0104] in, is the proportional coefficient, which is a parameter of the proportional element in a PID controller; is the integral coefficient, which is a parameter of the PID integral element; These are the differential coefficients, which are parameters of the PID differential element; The temperature difference of the target heating area. , A target temperature value preset for the target heating area. Output is the measured temperature value of the target heating area acquired by the temperature acquisition module; Output is the calculated control quantity, which is used to determine the conduction angle of the power regulation unit.

[0105] In the actual arrayed electric heating cable heating control system, after the main control module calculates the Output value, it also needs to calculate the allocation weight of each heating unit in the heating area according to the allocation strategy, and calculate the duty cycle of the PWM signal mapped to each heating unit. This allows the power control unit output from the designated pin to the corresponding heating unit, i.e., the optocoupler-type bidirectional thyristor, to adjust the conduction of the heating unit, thereby completing the corresponding adjustment of the input power of each heating unit.

[0106] After the allocation strategy is applied, the output value of the power control unit input to each heating unit is calculated. When the calculated output value is close to the maximum value, it means that the main control module outputs a high duty cycle PWM signal, so that the thyristor of the power control unit works in a fully or nearly fully conducting state, thereby maximizing the power input to the heating unit. By independently controlling each heating unit in the area, precise heating is achieved, and the area temperature rises. When the calculated output value decreases, the conduction angle of the corresponding power control unit decreases, thereby reducing the power input to the heating unit.

[0107] The above compensation calculation steps are performed independently for each heating zone. The PID algorithm calculation for the temperature deviation of each heating zone is independent of each other, ensuring that different heating zones can make accurate power adjustments according to their own temperature conditions. After the power adjustment amount is calculated, the main control module transmits the power adjustment amount of each heating zone to the temperature control step.

[0108] The temperature control step involves obtaining the corresponding compensation power for each heating unit in each heating zone according to the allocation strategy, and inputting it to the corresponding heating unit. The temperature value acquisition step, compensation calculation step, and temperature control step are repeated until the temperature deviation is less than the preset temperature difference threshold, so that the measured temperature value of the zone is close to the corresponding preset temperature value.

[0109] The specific allocation strategy in the above temperature control steps is as follows:

[0110] The relative position of each heating unit in the target heating area is obtained. This position refers to the specific orientation of a single heating unit in the target heating area. The position is divided into three categories: center position, internal position and edge position. It is a spatial parameter that determines the power distribution weight. It can be obtained by directly calling the position information pre-stored in the main control module.

[0111] The relative position of the target heating area with respect to the carrier is obtained. This position is used to determine the adjacency relationship between the target heating area and other heating areas, and to determine whether the cross-regional thermal coupling effect needs to be considered. The position information can be obtained by directly calling the pre-stored position information in the main control module.

[0112] The real-time heating temperature value of each heating unit in the target heating area is obtained. The real-time heating temperature value here refers to the accurate self-temperature value of the heating unit after correction by the self-temperature correction sub-strategy. This value reflects the actual heating state of the heating unit and is the core parameter for realizing on-demand power compensation.

[0113] Obtaining the measured temperature values ​​of the target heating area and its adjacent heating areas is to take into account the temperature of the adjacent heating areas when calculating the weight value of the heating unit located at the edge of the target heating area.

[0114] Based on the relative position of each heating unit in the target heating area, the real-time heating temperature value, and the measured temperature value of the heating area adjacent to the target heating area, the power regulation allocation weight value corresponding to each heating unit in the target heating area is calculated. The weight value is specifically the proportion that a single heating unit should be allocated in the total power regulation of the target heating area. This value is a dimensionless value between 0 and 1, and the sum of the weight values ​​of all heating units in each heating area is 1. The compensation power of each heating unit is calculated based on the power regulation and the allocation weight value.

[0115] The specific steps for calculating the weight of each heating unit are as follows:

[0116] The location baseline coefficient is obtained based on the location of the target heating unit within the heating area. Dimensionless, it can be directly calibrated based on its location; the center of the heating area corresponds to... =0.8; the corresponding position inside the heating zone =1.0; located at the edge of the heating area =1.2;

[0117] Based on the deviation between the real-time heating temperature of the target heating unit and the overall temperature of its heating area, on-demand power compensation is achieved, thereby obtaining the temperature deviation coefficient. Since it is dimensionless, the calculation formula is:

[0118]

[0119] in, The measured temperature value of the heating area is expressed in degrees Celsius. The real-time heating temperature of the target heating unit after temperature correction, in degrees Celsius.

[0120] For heating units located at the edge of the target heating region, the thermal influence of the temperature of adjacent heating regions on the edge heating units is calculated. For heating units located at the center and interior, this coefficient is 0. The cross-region thermal coupling coefficient is then calculated. Since it is dimensionless, its calculation formula is:

[0121]

[0122] in, The measured temperature value of the heating area is expressed in degrees Celsius. The measured temperature value of the heating area adjacent to the target heating unit, in degrees Celsius;

[0123] By combining the effects of location, temperature, and cross-regional thermal coupling on power distribution using the three single-factor coefficients mentioned above, the initial value of the comprehensive weight of the heating unit is obtained. The initial weight of each heating unit in the target heating area can be calculated using this formula.

[0124] Next, the initial comprehensive weight of all heating units within the target heating area is normalized to ensure that the sum of the weight values ​​of all heating units is 1, thus achieving complete allocation of the total power control. The weight of each heating unit can then be obtained as follows:

[0125]

[0126] in, Let be the initial weight of the i-th heating unit within the target heating area, where i is an integer from 1 to v, and v is the total number of heating units in the target heating area.

[0127] After calculating the weight values ​​for the power regulation amount, the main control module retrieves the total power regulation amount corresponding to the target heating area to calculate the compensation power for each heating unit. Then, the main control module outputs a signal to the power regulation unit corresponding to each heating unit and inputs the compensation power to the heating unit.

[0128] In addition, a compensation power adjustment strategy is incorporated into the temperature control process. This strategy is designed to ensure the safe and stable operation of the heating unit. By limiting the upper and lower limits of the input power of the heating unit, it prevents damage caused by over-power operation or heating failure and energy waste due to under-power operation, while ensuring reasonable power adjustment and the service life of the heating unit. Specifically:

[0129] The total input power is obtained by summing the compensation power of each heating unit with the current actual input power. The total input power is then compared with the rated maximum power. If it exceeds the rated maximum power, the rated maximum power is set as the input power of the heating unit. The total input power is then compared with the rated minimum power. If it is lower than the rated minimum power, the rated minimum power is set as the input power of the heating unit.

[0130] The rated maximum power and rated minimum power mentioned above are the electrical power limits that the heating unit is calibrated during the design and production stages to ensure long-term safe and stable operation.

[0131] Furthermore, the temperature control process involves repeated adjustments. During the repeated temperature value acquisition steps, after inputting compensation power to each heating unit in the heating area, it is necessary to keep the power output constant and continue for a preset stable time before collecting the regional temperature value of the heating area. The regional temperature value after determining whether the stable condition is met is used as the actual measured temperature value of the area.

[0132] The stability condition is specifically the rate of temperature change obtained by using the ratio of the temperature difference between the current temperature value and the previous temperature value to time, and the rate of temperature change is lower than the change threshold.

[0133] Through repeated temperature control adjustments, the temperature of the heating area gets closer and closer to the preset target temperature value, until the temperature difference of the heating area is less than the preset temperature difference threshold.

[0134] In one embodiment of the present invention, a fault judgment strategy is set in the temperature control step. This strategy identifies abnormal operation of the heating unit and triggers a fault alarm in a timely manner by dual monitoring of the continuous compensation behavior of the heating area and the effect of temperature change after compensation. This avoids the failure of the carrier temperature control due to heating unit failure, and at the same time achieves early warning and location of abnormalities, reducing system maintenance costs. Specifically:

[0135] The number of times continuous compensation steps are executed in each heating zone is accumulated and compared with the set threshold number. If the number exceeds the threshold number and the temperature deviation is still greater than the temperature difference threshold, it is determined that there is an abnormality in the heating unit under that heating zone, triggering a fault alarm. The continuous compensation step refers to the continuous operation process of continuously executing compensation calculation steps and temperature control steps in the heating zone because the temperature deviation is greater than the temperature difference threshold. Each time the compensation power is input and the temperature value is collected after waiting for thermal equilibrium, it is considered as one compensation step. The number of continuous control steps is accumulated by the main control module. When the temperature deviation of the heating zone is less than the temperature difference threshold, the counter is immediately cleared to zero and the initial state is restored. The threshold number refers to the upper limit of the number of continuous compensation steps preset to determine whether there is an abnormality in the heating zone.

[0136] The system obtains the measured temperature of the heating zone after two consecutive compensation adjustments, calculates the absolute value of the temperature change between the two consecutive measured temperatures, and compares it with the set change threshold. If the change threshold is less than the change threshold and the temperature deviation is still greater than the temperature difference threshold, it is determined that there is an abnormality in the heating unit in the heating zone, triggering a fault alarm. The change threshold refers to the lower limit of temperature change preset to determine whether the compensation adjustment of the heating zone is effective. When the absolute value of the temperature change after two consecutive compensations is less than this value, the compensation adjustment is considered invalid.

[0137] In a practical arrayed electric heating cable control system, after a fault alarm is triggered, the main control module will simultaneously execute multiple linkage operations. First, the fault information is transmitted to the human-machine interaction module in real time, and the location information of the fault heating area is displayed on the OLED screen, making it convenient for on-site operators to check in a timely manner. Second, the fault information is uploaded to the remote monitoring platform through the wireless communication module. The platform will immediately send an alarm notification to the management personnel, including key information such as the location of the fault area and the time of the fault, to achieve remote early warning.

[0138] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling arrayed electric heating tape, characterized in that, The control method specifically includes: The control circuit establishment step involves dividing the carrier into several heating areas, and setting multiple independent heating units in each heating area, with a power regulation unit configured for each heating unit to form a one-to-one control link. The temperature value acquisition step involves acquiring the real-time voltage and real-time current of each heating unit to obtain the real-time resistance value of each heating unit. The real-time resistance value is then used as an index to search for a matching real-time heating temperature value in a preset resistance-temperature baseline. The real-time heating temperature value represents the estimated self-temperature value of the heating unit at the current moment. The compensation calculation step involves obtaining the measured temperature value of each heating zone and comparing it with the preset temperature value of each heating zone to obtain the temperature deviation of each heating zone. The temperature deviation is then input into the PID algorithm to obtain the power control amount corresponding to each heating zone. The temperature control step involves obtaining the corresponding compensation power for each heating unit in each heating zone according to the allocation strategy, and inputting it to the corresponding heating unit. The temperature value acquisition step, compensation calculation step, and temperature control step are repeated until the temperature deviation is less than the preset temperature difference threshold, so that the measured temperature value of the zone is close to the corresponding preset temperature value. The temperature value acquisition step is configured with a heating unit self-temperature correction sub-strategy. After the real-time heating temperature value is found from the resistance-temperature baseline, the heating unit self-temperature correction sub-strategy is executed, specifically as follows: Record the cumulative power-on time for each heating unit, and calculate the duration aging correction amount based on the cumulative power-on time; The real-time heating temperature value of the heating unit is obtained by matching the resistance-temperature baseline. The temperature difference between the heating unit and the adjacent heating unit is calculated based on the real-time heating temperature value of the heating unit and the corresponding adjacent heating unit. The thermal coupling correction amount is then calculated using the preset thermal coupling coefficient. The temperature value obtained by summing the real-time heating temperature value of the heating unit with the time aging correction amount and the thermal coupling correction amount is used as the corrected real-time heating temperature value of the heating unit.

2. The arrayed electric heating tape heating control method according to claim 1, characterized in that, The specific allocation strategy is as follows: Obtain the relative position of each heating unit in the target heating area with respect to the target heating area and the relative position of the target heating area with respect to the carrier. The system acquires the real-time heating temperature value of each heating unit in the target heating area, as well as the measured temperature value of the target heating area and the measured temperature value of the adjacent heating areas. Based on the relative position of each heating unit in the target heating area, the real-time heating temperature value, and the measured temperature value of the heating area adjacent to the target heating area, the power regulation allocation weight value corresponding to each heating unit in the target heating area is calculated, and the compensation power of each heating unit is obtained based on the power regulation allocation weight value.

3. The method for controlling arrayed electric heating tape according to claim 1, characterized in that, The adjacent heating units include adjacent heating units within the same heating area of ​​the heating unit, and cross-regional adjacent heating units in other heating areas that are adjacent to the heating area of ​​the heating unit.

4. The method for controlling arrayed electric heating tape according to claim 1, characterized in that, The specific steps for establishing the resistance-temperature baseline are as follows: In the simulated constant temperature chamber, by adjusting the power of the input heating unit and the temperature of the constant temperature chamber, and keeping the current working conditions unchanged and letting it stand still for a period of time, the temperature and resistance values ​​are collected. When it is determined that the temperature change rate and resistance change rate of the heating unit are both lower than the threshold, the current moment is a stable state and the resistance and temperature values ​​of the heating unit are recorded at this time. The recorded resistance values, temperature values, and ambient temperature values ​​are combined into a set of data, and multiple sets of data are combined into a dataset. By establishing a fitting relationship with the dataset, the resistance-temperature baseline of the heating unit is obtained.

5. The arrayed electric heating tape heating control method according to claim 1, characterized in that, In the repeated temperature value acquisition step, after inputting compensation power to each heating unit in the heating area, the power output is kept constant and the area temperature value of the heating area is collected after a preset stable time. The area temperature value that meets the stable condition is determined as the actual measured temperature value of the area. The stability condition is specifically the rate of temperature change obtained by the ratio of the temperature difference between the current temperature value and the previous temperature value to time, and the rate of temperature change is lower than the change threshold.

6. The arrayed electric heating tape heating control method according to claim 1, characterized in that, The temperature control step includes a fault diagnosis strategy, specifically comprising: The number of times the continuous compensation step is executed in each heating zone is accumulated and compared with the set number threshold. If the number of times exceeds the threshold and the temperature deviation is still greater than the temperature difference threshold, it is determined that there is an abnormality in the heating unit under that heating zone, and a fault alarm is triggered. The system obtains the measured temperature of the heating zone after two consecutive compensation adjustments, calculates the absolute value of the temperature change between the two consecutive measured temperatures, and compares it with the set change threshold. If the change is less than the change threshold and the temperature deviation is still greater than the temperature difference threshold, it is determined that there is an abnormality in the heating unit in the heating zone, and a fault alarm is triggered.

7. The arrayed electric heating tape heating control method according to claim 1, characterized in that, The temperature control step also includes a compensation power adjustment strategy, specifically: The total input power is obtained by summing the compensation power of each heating unit with the current actual input power. The total input power is then compared with the rated maximum power. If the total input power exceeds the rated maximum power, the rated maximum power is set as the input power of the heating unit. Compare the total input power with the rated minimum power; if the total input power is lower, then the rated minimum power is set as the input power of the heating unit.

8. A heating control system for arrayed electric heating cables, applicable to the heating control method for arrayed electric heating cables as described in any one of claims 1-7, characterized in that, The system includes: The main control module stores the control link addresses of all heating units and the resistance-temperature baseline, and is used to run compensation calculation steps and execute control logic tasks. The power drive and control module includes a power regulation unit that regulates the power of each heating unit. The power regulation unit is used to receive control signals from the main control module to adjust the conduction of the power regulation unit. The power regulation unit is used to regulate the power input to the heating unit. The temperature acquisition module is used to collect the measured temperature values ​​of each heating zone. The power supply module is used to provide power to each module. The wireless communication module is used for data interaction between the main control module and the remote monitoring platform. The human-computer interaction module is used to display on-site working parameter information and allows local parameter setting and operation; The remote monitoring platform is used to display the real-time operating parameters of each heating unit and is responsible for alarm management and remote control.

9. A heating control system for arrayed electric heating cables according to claim 8, characterized in that, The heating unit is an electric heating tape.

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