Gradient temperature control integrated temperature controller and heating control method

Abstract

The invention provides a gradient temperature control integrated temperature controller and a heating control method, the gradient temperature control integrated temperature controller comprises a self-tuning mode, a temperature control mode and a slope temperature control mode, the self-tuning mode is used for setting full amplitude output, adapting to different loads, respectively measuring delay time and overshoot, and obtaining adaptive PID parameters according to an improved ZN empirical method; wherein Ku is a system gain, integral division is used for calculation of Ku, the Ku is used for replacing an original amplitude value, and the gain effect of system transfer function is embodied; in the slope temperature control mode, an actual temperature rise slope is adopted as a feedback quantity, deviation calculation is carried out on the feedback quantity and set input, and load linear temperature rise control is carried out according to a calculated current PID parameter; the delay time is heat transfer delay time after output is closed in the self-tuning process, and returning the calculation function result to the delay sequence. According to the invention, a self-tuning temperature control function, a slope heating function and a PID temperature control function can be realized, the temperature control requirements of various special process loads can be met, manual adjustment is replaced, and the debugging period is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature control, and in particular, to a gradient temperature control integrated thermostat and a heating control method. Background Art

[0002] Most of the existing thermostats belong to temperature control type thermostats, that is, a certain temperature is set, and then the power supply is driven to continuously heat the load, and it is impossible to control the temperature rise according to special process requirements, such as being unable to meet the special application scenarios of semiconductor equipment: different temperature control settings for different load components, etc.

[0003] When using the PID (Proportional Integral Derivative) control algorithm to configure corresponding parameters for different loads in the prior art, it is necessary to repeatedly heat, manually set parameters, the operation is complex, the debugging takes a long time, and the adaptability is poor, unable to meet the production requirements.

[0004] Therefore, a new solution for gradient temperature control integrated thermostat is needed. Summary of the Invention

[0005] In view of this, the present invention provides a gradient temperature control integrated thermostat and a heating control method.

[0006] The present invention provides the following technical solutions:

[0007] The embodiment of the present specification also provides a heating control method for a gradient temperature control integrated thermostat, including: three control methods: self-tuning mode, temperature control mode, and slope temperature control mode. Among them, the self-tuning mode is used to set the full amplitude output, adapt to different loads, respectively measure the delay time and overshoot, and obtain the appropriate PID parameters according to the improved ZN empirical method;

[0008] The improved ZN empirical method determines the preset parameter values through the system response curve. Using the response curve obtained by the first application of the pulse signal excitation to obtain the delay time, using the response curve obtained by the second application of the pulse signal excitation to find the response period Tp, and then calculating the values of Kp, Ki, and Kd from the gain Ku, where K u is the system gain, K u is calculated using integral division, which is used to replace the original amplitude, reflecting the gain effect of the system transfer function, as shown in Formula 1:

[0009] Among them, and respectively represent the maximum output value and the minimum output value, which are the full amplitude value and 0 respectively, D is the duty cycle of the pulse, that is, the pulse width t of the full amplitude pulse input HThe ratio to the time t from when the corresponding load temperature drops to 1°C below the target value to when it rises to the highest point and then drops below the target value again u ; t start is t H ; t end is t u ;

[0010] Under the described temperature control mode, an equivalent gain is obtained by using the traditional PID temperature control method in combination with the changed partial parameters in the self-tuning mode to control the integral term;

[0011] Under the described slope temperature control mode, the actual temperature value is obtained, and the slope of the actual temperature rise is used as the feedback value, and the deviation is obtained from the target temperature value. The load is linearly heated to the target temperature according to the current PID parameters calculated by the improved ZN empirical method;

[0012] Wherein: the delay time is the heat transfer delay time after the output is turned off during the self-tuning process, and the delay sequence for returning the calculation function result to the temperature controller control program.

[0013] The present invention provides a gradient temperature control integrated temperature controller, which applies the gradient temperature control integrated temperature controller heating control method described in the above technical solution, including:

[0014] A power supply circuit, a drive circuit, a temperature sampling circuit, and a temperature control unit;

[0015] The power supply circuit and the drive circuit are respectively connected to the temperature control unit;

[0016] The temperature sampling circuit is used to collect the actual temperature of the load in real time and send the collected actual temperature to the temperature control unit;

[0017] The drive circuit is controlled by the pulse width modulation drive signal issued by the temperature control unit to drive the load;

[0018] The power supply circuit is used to supply power to each module and provide power input to the load;

[0019] The temperature control unit is used to run the temperature controller control program according to the actual temperature, adjust the PID parameters to control the load to linearly rise to the specified temperature; wherein, the temperature controller control program includes a self-tuning mode, a temperature control mode, and a slope temperature control mode.

[0020] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of the present specification at least include:

[0021] The embodiments of this specification design a gradient temperature control integrated thermostat and a heating control method. In this method, the temperature control unit uses an improved Ziegler–Nichols empirical method (abbreviated as the ZN empirical method) to output through a relay function, realizing single-cycle tuning calculation. Based on the original method, the heat transfer delay time is increased for system delay. The delay time is the heat transfer delay time after the output is turned off during the self-tuning process, making it more suitable for inertial loads with long lags, such as the working conditions of heating tapes equipped with heat-insulating and airtight sheaths. It realizes the function of slope temperature rise, can control the load to linearly rise to the specified temperature, and meets special process requirements. It can perform rapid self-tuning for inertial loads and lag loads, replacing manual tuning, effectively reducing development and maintenance costs, and greatly shortening the equipment debugging cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 is a schematic diagram of the architecture of a gradient temperature control integrated thermostat according to an embodiment of the present invention Figure 1

[0024] Figure 2 is a schematic diagram of the self-tuning mode curve in an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of the architecture of a gradient temperature control integrated thermostat according to an embodiment of the present invention Figure 2 ;

[0026] Figure 4 is a flowchart of the PID control program of a gradient temperature control integrated thermostat according to an embodiment of the present invention;

[0027] Figure 5 is a flowchart of the self-tuning algorithm of a gradient temperature control integrated thermostat and a heating control method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following will describe the embodiments of this application in detail with reference to the drawings.

[0029] The following describes the embodiments of the present application through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. The present application can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0030] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0031] It should also be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application schematically. The diagrams only show the components related to the present application, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in its actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0032] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the examples can be practiced without these specific details.

[0033] Most of the existing temperature controllers belong to temperature control type temperature controllers and cannot control the temperature rise according to special process requirements. When using the PID control algorithm in the prior art to configure corresponding parameters for different loads, it is necessary to repeatedly heat and manually set parameters. The operation is complex, time-consuming, and the adaptability is poor, unable to meet the production requirements.

[0034] Based on this, the embodiments of this specification propose a new solution for a gradient temperature control integrated thermostat and a heating control method. The self-tuning algorithm based on the relay self-tuning method and the improved ZN empirical method is used to quickly tune the PID parameters. By giving two full-amplitude outputs, the delay time, overshoot, and the balanced output amount under the current environment are measured respectively. On the original basis, a heat transfer delay link is added to the system delay to make it more suitable for inertial loads with long lags, such as the working conditions of heating tapes equipped with heat-insulating and airtight sheaths. Then, the PID parameters are calculated according to the improved ZN empirical method, which can control the load to linearly rise to the specified temperature, shorten the overall cycle and reduce the complexity of tuning, and improve the tuning efficiency.

[0035] The following will describe the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.

[0036] As Figures 1 to 3 shown, a gradient temperature control integrated thermostat provided by the embodiments of this specification includes: a temperature sampling circuit and a temperature control unit;

[0037] The temperature sampling circuit is used to collect the actual temperature of the load in real time and send the collected actual temperature to the temperature control unit;

[0038] The temperature control unit is used to perform gradient temperature control on the load in the self-tuning mode according to the actual temperature and the preset target temperature. The gradient temperature control in the self-tuning mode includes: when the load is first heated from the actual temperature to the target temperature, the load is driven to heat up with a full-amplitude output, and when the actual temperature first reaches the first monitoring threshold corresponding to the target temperature, the output is turned off and the time t1 at this moment is recorded; then, after the output is turned off and waiting until the actual temperature rises to the preset maximum value, the time t2 at this moment is recorded; and, continue to wait until the actual temperature drops to the second monitoring threshold corresponding to the target temperature, and then drive the load to heat up again with a full-amplitude output until the actual temperature reaches the first monitoring threshold corresponding to the target temperature again, and then turn off the output and record the time t3 at this moment; then, the corresponding parameters required for PID control in a single self-tuning cycle: Kp, Ki, and Kd are obtained according to t1, t2, and t3 by using the ZN empirical method, and the parameters are used for the PID control after self-tuning.

[0039] Among them, the temperature sampling circuit is used to obtain the collected temperature signal from the temperature sensor at a fixed cycle and process the temperature signal to eliminate the influence of fluctuations to obtain an effective temperature signal, that is, to collect the actual temperature of the load.

[0040] The temperature control unit such as the MCU and its peripheral circuits is used to run the thermostat control program according to the actual signal, adjust the PID parameters, and control the load to linearly rise to the specified temperature.

[0041] Specifically, it can be divided into three modes: self-tuning mode, temperature control mode, and slope temperature control mode. Among them, the self-tuning mode is used to set the full-amplitude output, adapt to different loads, measure the delay time and overshoot respectively, and obtain the appropriate PID parameters according to the improved ZN empirical method; the temperature control mode uses the traditional PID temperature control method combined with some updated parameters in the self-tuning mode to control the integral term; the slope temperature control mode realizes linear heating up to the target value for special process requirements.

[0042] Specifically, in the self-tuning mode, the temperature controller control program is set to the full-amplitude output target value. By measuring the delay time and overshoot respectively, the PID parameters are obtained according to the improved ZN empirical method. The self-tuning mode realizes the self-tuning process of PID parameters through two full-amplitude pulse outputs. Among them: the delay time is the heat transfer delay time after the output is turned off during the self-tuning process, and the calculation function result is returned to the delay sequence of the temperature controller control program.

[0043] According to the improved ZN empirical method, the appropriate parameter values are determined through the system response curve (or by applying the ZN empirical method formula). Using the response curve obtained by the first pulse signal excitation, the delay time is obtained. Using the response curve obtained by the second pulse signal excitation, the response period (Tp) and gain (Ku) are obtained, and then the values of Kp, Ki, and Kd are calculated. Among them, K u is the system gain, K u is calculated using integral division (as shown in Formula 1 below), replacing the original amplitude, which is closer to the actual working condition and reflects the gain effect of the system transfer function. Among them, the response curve is obtained by applying a step signal to the load to obtain a curve similar to Figure 2 while maintaining key moments such as t1, t2, and t3 in the self-tuning mode.

[0044] In the temperature control mode, the traditional PID temperature control method is used in combination with some changed parameters (such as equivalent gain) in the self-tuning mode to control the integral term corresponding to the change curve.

[0045] In the slope temperature control mode, the actual temperature rise slope is used as the feedback quantity, the deviation is obtained from the set input, and the load linear heating is controlled according to the calculated current PID parameters;

[0046] That is, the slope temperature control mode is used to control the load to linearly heat up to the specified temperature (i.e., the target temperature) according to the temperature rise speed and the real-time temperature deviation by using the currently adjusted PID parameters.

[0047] Specifically, most of the existing thermostats belong to temperature control type thermostats, which cannot control the heating rate according to special process requirements such as heating belts and heating wires in semiconductor manufacturing processes. Even when using the PID control algorithm and configuring corresponding parameters for different loads, it is still necessary to perform repeated heating and cooling processes and manually adjust the parameters. The operation is complex, the adaptability is poor, and the time consumption is long.

[0048] Based on the above three modes of the temperature control unit, these three modes can be commanded by a host computer such as Figure 1 shown in the example. According to the command given by the host computer, one of the three modes is executed.

[0049] The gradient temperature control integrated thermostat in the embodiment of this specification adopts an improved relay self-tuning method to make the system generate a single-cycle oscillation. By giving two full-amplitude pulse outputs, the heat transfer delay time and overshoot amount including the added ones are measured respectively, and then the PID parameters are calculated by the ZN empirical method after modifying the coefficient (such as equivalent gain) in combination with the actual system, and the period and overshoot amount are measured quickly. As Figure 5 shown, see the following description for details. After actual measurement and tuning, the overshoot amount and overshoot time meet the special process requirements of semiconductors and can control the load to linearly increase the temperature. Among them, the overshoot amount is the maximum amplitude by which the output exceeds the set value. The overshoot time refers to the time when the system output first exceeds the target set value. It reflects the time for the system to reach above the set value from the initial state in the step response and is an important index of the dynamic performance of the system during actual operation. The length of the overshoot time depends on the proportional P, integral I, differential D, and the characteristics of the system.

[0050] Among them, the heat transfer delay time is measured during self-tuning, that is, a heat transfer delay link is added to the system delay on the original basis. The delay time is the heat transfer delay time after the output is turned off during the self-tuning process, so that it can conform to the working conditions of inertial loads with long lags, such as heating belts equipped with heat preservation and airtight sheaths, and the calculation function result is returned to the delay sequence to achieve delay.

[0051] The delay time is the time required for the system output to drop from the set value to a certain specific value (such as a certain percentage of the set value) after the output is turned off during the self-tuning process. The delay time is a parameter used to evaluate the dynamic characteristics of the system during the self-tuning process and is reference data for optimizing the PID parameters.

[0052] As Figure 3 shown, a gradient temperature control integrated thermostat provided by the embodiment of this specification further includes: a power supply circuit and a drive circuit.

[0053] Such as the MCU and its peripheral circuits, which are used to run the thermostat control program according to the actual temperature, adjust the PID parameters, and control the load to linearly increase the temperature to the specified temperature;

[0054] A drive circuit, controlled by a PWM drive signal issued by an MCU, for driving a load;

[0055] A power supply circuit, for supplying power to each module and providing power input to the load.

[0056] In some embodiments, it further includes an indication circuit, an RS485 communication circuit or a DeviceNet communication module. The indication circuit, the RS485 communication circuit and the DeviceNet communication module are respectively connected to the temperature control unit. The indication circuit is used to indicate the output power supply state and the power supply state of the load; the indication circuit includes an LED (Light Emitting Diode) indicator light, a digital tube, an OLED (Organic Light-Emitting Diode), a dot matrix LCD (Liquid Crystal Display), a field or a cold light tube; the indication circuit includes 5 red LEDs; the RS485 communication circuit or the DeviceNet communication module is used to realize communication with the host computer.

[0057] The gradient temperature control integrated thermostat in the embodiments of this specification further includes a communication circuit or a communication module, such as Figure 3 As shown, an RS485 communication circuit and a DeviceNet communication module, for realizing communication with the host computer, and respectively setting their corresponding ports.

[0058] In some embodiments, communication with the host computer can be carried out through a communication port. For example, by setting RS485 and DeviceNet communication ports, the communication requirements with other field devices can be met. Let the self-tuning process be realized through the host computer (such as but not limited to personal computers, industrial computers and embedded controllers, etc.), and the required process parameters are transmitted in real time through the bus. After the tuning is completed, the parameters are stored in the thermostat.

[0059] The indication circuit is composed of 5 red LEDs, for indicating the output power supply state and the power supply state of 4 heater circuits. The indication circuit is not limited to LED indicator lights, and forms such as digital tubes, OLEDs, dot matrix LCDs, fields, and cold light tubes can be used.

[0060] In some embodiments, the drive circuit includes a silicon controlled rectifier (SCR), an insulated gate bipolar transistor (IGBT), silicon carbide (SiC), and a metal-oxide-semiconductor field-effect transistor (MOSFET); among them, the drive circuit includes 4 SCRs.

[0061] The drive circuit is composed of 4 SCRs and is controlled by the PWM drive signal sent by the temperature control unit to adjust the output power.

[0062] The drive circuit is not limited to using SCRs and can also use various solutions such as IGBTs, SiCs, and MOSFETs.

[0063] In some embodiments, the power supply circuit includes an input filter circuit, an AC / DC module, and an LDO (low dropout regulator) circuit; among them, the AC / DC module is used to convert 208VAC into 5VDC, where 208VAC can also be 110 - 240VAC, and the LDO circuit is used to provide a 3.3VDC power supply voltage for the temperature control unit.

[0064] In some embodiments, the gradient temperature control integrated thermostat further includes a temperature sensor. The temperature sensor is connected to the temperature sampling circuit, and the temperature sensor transmits the acquired temperature signal to the temperature sampling circuit.

[0065] The temperature sensor includes a thermocouple; the gradient temperature control integrated thermostat is connected to 4 electric heating loads.

[0066] The load includes a heating tape or a heating wire; the load current is 6A;

[0067] Each load is separately provided with a timer in the temperature control unit. In the interrupt service routine (ISR) corresponding to the timer, the temperature of the measured point and the time slice number (used to obtain the heat transfer delay time, such as obtaining the heat transfer delay time according to the value of the time slice number in the conventional manner) are obtained; the load includes an inertial load or a lag load.

[0068] Among them, the function of the timer is to trigger temperature sampling and control operations periodically. The timer will trigger an interrupt signal at a set time interval. When the interrupt signal is triggered, the temperature control unit will execute an interrupt service routine. The function of the interrupt service routine is to interrupt the current main program and perform operations such as temperature sampling. That is, in the interrupt service routine, the temperature control unit will obtain the actual temperature value of each load through the temperature sampling circuit.

[0069] The embodiment of this specification uses an internal four-channel hardware timer to trigger interrupts, avoiding the timing deviation that may occur during the query and jump processes when using a single timer, and ensuring the accuracy of the discretized sampling period of the integral term.

[0070] In some embodiments, the gradient temperature control integrated thermostat is disposed inside a preset product.

[0071] The embodiment of this specification adopts an integrated solution, integrating the control loop and the main loop (such as the temperature sampling circuit, the power supply circuit, the temperature control unit, the drive circuit, the indication circuit, the RS485 communication circuit, and the DeviceNet communication module) inside the product module, eliminating a large number of external connection wires, facilitating installation, further saving installation space, and reducing installation man-hours.

[0072] As Figure 4 shown, in the embodiment of this specification, the drive circuit of the gradient temperature control integrated thermostat is connected to the load and outputs at full rated value of the set target. Since the load usage environment is different, to implement the self-tuning function, the set temperature - ambient temperature should be greater than 2°C. After the load and the environment are balanced, the collected temperature is used as the ambient temperature to ensure that key parameters such as overshoot, overshoot time, and delay time can be measured through two full-amplitude pulse outputs in the self-tuning method. At the same time, the current temperature value is sampled in real time and transmitted to the temperature control unit, and through the improved PID formula calculation, the actual temperature value is output until the specified duty cycle PWM signal is output to meet the set target requirements.

[0073] Combined with the above embodiments, the embodiment of this specification also provides a heating control method for a gradient temperature control integrated thermostat, including using an improved relay self-tuning method to make the system generate a single-cycle oscillation, measuring the delay time and overshoot respectively through 2 full-amplitude outputs, obtaining the PID parameters according to the improved ZN empirical method, where the heat transfer delay time is added to the delay time; in the temperature control mode, the equivalent gain is obtained by using the traditional PID temperature control method combined with some changed parameters in the self-tuning mode to control the integral term. Furthermore, the slope temperature control mode is realized. In the present invention, the improved self-tuning method replaces the existing manual adjustment method.

[0074] Specifically, in the self-tuning mode, it is heated to the target temperature value by outputting full amplitude twice successively. The delay time is measured for the first time, and the heat transfer delay time is added to the delay time. For the second time, the actual oscillation period and the period data of the oscillation near the target temperature are obtained, so as to obtain the oscillation period and the overshoot corresponding to the target temperature in the oscillation period.

[0075] According to the improved ZN empirical method, the appropriate parameter values are determined through the system response curve (or by applying the ZN empirical method formula). Using the response curve obtained by exciting with the first pulse signal, the delay time is obtained. Using the response curve obtained by exciting with the second pulse signal, the response period (Tp) and the gain (Ku) are obtained, and then the values of Kp, Ki, and Kd are calculated. Among them, K u is the system gain, and K u is calculated by integral division, replacing the original amplitude, which is closer to the actual working condition and reflects the gain effect of the system transfer function. The formula is as follows:

[0076] Among them, and represent the maximum output value and the minimum output value respectively, which are the full amplitude value and 0 respectively. D is the duty cycle of the pulse, that is, the pulse width (t H ) of the full amplitude pulse input and the time (t u ) from the corresponding load temperature dropping to 1°C below the target value to rising to the highest point and then falling back to 1°C below the target value again. The ratio. t start is t H , and t end is t u .

[0077] In the improved self-tuning algorithm of the present invention, K u is calculated by integral division, replacing the original amplitude, which is closer to the actual working condition and reflects the gain effect of the system transfer function. The formula is as follows:

[0078]

[0079] In the temperature control mode, the equivalent gain is obtained by combining the traditional PID temperature control method with some changed parameters in the self-tuning mode to control the integral term. The equivalent gain is used to indicate the overall strength of the response to the deviation signal, especially for controlling the integral term.

[0080] In the slope heating mode, the slope of the actual temperature rise is used as the feedback value (that is, when calculating using the PID transfer function, the temperature difference between the actual collected temperature and the previous moment temperature is used as the input for calculation, which is equivalent to taking the derivative on both sides of the formula) until the response curve stabilizes near the set value. At this time, the improved ZN empirical method is continued to control the load to linearly rise to the specified temperature (i.e., the target temperature).

[0081] The working process of the slope heating mode is as follows Figure 4 As shown, obtain the actual temperature value, and use the slope of the actual temperature increase as the feedback value, and calculate the deviation from the target temperature heating rate; according to the current PID parameters calculated by the improved ZN empirical method in the self-tuning mode, control the load to linearly heat up to the specified temperature.

[0082] Specifically, use the slope of the actual temperature rise as the feedback value. That is, when using the PID transfer function for calculation, use the difference between the actually collected temperature and the temperature at the previous moment as the input for calculation, which is equivalent to taking the derivative on both sides of Formula 2. Formula 2 is

[0083] where N is the length of the array associated with the delay time (i.e., the corresponding delay sequence), ΔT is the sampling and control period, T n is the temperature of the controlled object collected at the current moment, and T n-1 represents the sampled temperature in the previous cycle.

[0084] In the embodiment of this specification, after the drive circuit is connected to the load, set the target temperature value. Through full amplitude output, use the improved relay self-tuning method to measure the delay time, and return the calculation function result value to the delay sequence, so as to add the heat transfer delay time in the delay time. That is, through the relay function output, realize the single-cycle tuning calculation, and add a delay link to the system delay on the original basis, making it more in line with the working conditions of inertial loads with long lags, such as heating tapes equipped with heat preservation and airtight sheaths. In the slope temperature control mode, use the slope of the actual temperature rise as the feedback value. That is, when using the PID transfer function for calculation, use the difference between the actually collected temperature and the temperature at the previous moment as the input for calculation, which is equivalent to taking the derivative on both sides of Formula 2, replacing the manual adjustment in the prior art, realizing the slope heating function of the load, and meeting the heating requirements of special process loads such as heating tapes and heating wires.

[0085] The self-tuning mode can reduce the workload of the debugging personnel and shorten the manual debugging period.

[0086] Such as Figure 5 As shown, that is, in the self-tuning, through two full amplitude outputs, measure the delay time and overshoot respectively, and calculate the PID parameters according to the improved ZN empirical method, realize the special process requirements in the semiconductor manufacturing process, realize the slope heating function, and control loads such as heating tapes in the semiconductor manufacturing process to linearly heat up to the specified temperature.

[0087] Specific example: First, the upper computer sets the target temperature. After the temperature controller receives the message, it discriminates according to the measured load temperature. When the target temperature is more than 2 degrees Celsius higher than the ambient temperature, start self-tuning, otherwise return a prompt message and standby.

[0088] Taking the load temperature before self-tuning as 45°C as an example, set the target temperature to 80°C. When the condition that the target temperature is 2°C higher than the load temperature is met, enter the self-tuning step. Record the current time (t0), save the variable for timer timing, output at full amplitude, collect the load temperature regularly. When the load temperature reaches 80°C (target temperature), turn off the output, record the current time (t1), and keep the temperature collection at a fixed period continuing. When the temperature rises to the maximum value, record the current time (t2). The delay time Δt = t2 - t1 can be calculated, and the delay time is obtained through Δt. When the temperature drops to 80°C (set temperature), output at full amplitude. When the temperature reaches 80°C (set temperature) again, record the current time (t3). Thus, the parameters of a single cycle can be obtained in the shortest time, and then the Kp, Ki, and Kd parameters are obtained according to the improved ZN empirical method for the control parameters after tuning.

[0089] Combined with the above embodiments, the embodiments of this specification use the relay self-tuning method. The first full-amplitude output is used to measure the delay time, and the second full-amplitude output is used to obtain the oscillation period and the overshoot corresponding to the target temperature in the oscillation period. Then, the Kp, Ki, and Kd parameters are obtained according to the ZN empirical method, completing the parameter tuning in a relatively short time. Compared with the existing manual adjustment method, the installation and commissioning period is shortened.

[0090] In the self-tuning method, the integral of the load temperature curve caused by the second pulse input is used as the denominator, and the average amplitude of the second pulse output is used as the input to obtain the equivalent gain.

[0091] In the embodiments of this specification, the temperature control unit sets a timer for each load. The interrupt service program corresponding to the timer is used to obtain the temperature of the measured point and calculate the heat transfer delay time to ensure the discretization of the integral term. The load is an inertial load and a lag load.

[0092] This application uses the improved Ziegler–Nichols empirical method (abbreviated as ZN empirical method) to realize single-cycle tuning calculation through the relay function output. On the original basis, a delay link is added for the system delay to make it more suitable for inertial loads with long lags, such as the working conditions of heating tapes equipped with heat-insulating and airtight sheaths. In the gain calculation, the output and the integral of the input are used for calculation, and the effect is better than the traditional method based on multiplying the amplitude of the fundamental component by the compensation coefficient, and it is easier to reflect the average gain characteristics over a longer period.

[0093] This application has a slope heating function, which can control the load to linearly heat up to the specified temperature to meet special process requirements.

[0094] This application can perform rapid self-tuning for inertial loads and hysteretic loads, replacing manual debugging, effectively reducing development and maintenance costs, and greatly shortening the equipment debugging cycle.

[0095] This application has RS485 and DeviceNet communication ports, which can meet the communication requirements with other field devices.

[0096] In the self-tuning mode of this application, the calculation of K u uses integral division instead of the original amplitude, which is closer to the actual working conditions and reflects the gain effect of the system transfer function. The formula is as follows:

[0097] In addition, this application adopts an integrated solution, integrating the control loop and the main loop inside the product module, eliminating a large number of external connection wires, facilitating installation, further saving installation space, and reducing installation man-hours.

[0098] For the various embodiments in this specification, the same or similar parts can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the product embodiments described later, since they correspond to the methods and are relatively simply described, the relevant parts can be referred to the descriptions in the system embodiments.

[0099] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by this application should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A heating control method for a gradient temperature control integrated thermostat, characterized in that, Including: Three control methods: self-tuning mode, temperature control mode, and slope temperature control mode. Among them, the self-tuning mode is used to set the full-amplitude output, adapt to different loads, measure the delay time and overshoot respectively, and obtain the appropriate PID parameters according to the improved ZN empirical method; The improved ZN empirical method determines the preset parameter values through the system response curve. Using the response curve obtained by the first application of the pulse signal excitation, the delay time is obtained. Using the response curve obtained by the second application of the pulse signal excitation, the response period Tp is obtained, and the gain Ku is used to calculate the values of Kp, Ki, and Kd, where K u is the system gain, K u is calculated using integral division, which is used to replace the original amplitude and reflects the gain effect of the system transfer function. As shown in Equation 1: Among them, Po max and Po min represent the maximum output value and the minimum output value respectively, which are the full amplitude value and 0. D is the duty cycle of the pulse, that is, the pulse width t H of the full amplitude pulse input, and the ratio of the time t u from when the corresponding load temperature drops to 1°C below the target value to when it rises to the highest point and then drops back below the target value again; t start is t H , t end is t u ; In the temperature control mode, the equivalent gain is obtained by using the traditional PID temperature control method combined with some parameters changed in the self-tuning mode to control the integral term; In the slope temperature control mode, the actual temperature value is obtained, and the slope of the actual temperature rise is used as the feedback value, and the deviation is calculated with the target temperature value. The load is linearly heated to the target temperature according to the current PID parameters calculated by the improved ZN empirical method; Among them: the delay time is the heat transfer delay time after the output is turned off during the self-tuning process, and the calculation function result is returned to the delay sequence of the temperature controller control program.

2. The gradient temperature control integrated thermostat heating control method according to claim 1, wherein The relay self-tuning method is used to measure the delay time through the first full-amplitude output, and the second full-amplitude output is used to obtain the oscillation period and the overshoot corresponding to the target temperature in the oscillation period.

3. The gradient temperature control integrated thermostat heating control method according to claim 1, characterized in that In the self-tuning method, the integral of the load temperature curve caused by the second pulse input is used as the denominator, and the average amplitude of the second pulse output is used as the input to obtain the equivalent gain.

4. The gradient temperature control integrated thermostat heating control method according to claim 1 or 2 or 3, characterized in that, The temperature control unit sets a timer for each load respectively. The interrupt service program corresponding to the timer is used to obtain the temperature of the measured point and calculate the heat transfer delay time to ensure the discretization of the integral term.

5. A gradient temperature control integrated thermostat, characterized in that, Applying the gradient temperature control integrated temperature controller heating control method according to any one of claims 1-4, including: a power supply circuit, a drive circuit, a temperature sampling circuit, and a temperature control unit; The power supply circuit and the drive circuit are respectively connected to the temperature control unit; The temperature sampling circuit is used to collect the actual temperature of the load in real time and send the collected actual temperature to the temperature control unit; The drive circuit is controlled by the pulse width modulation drive signal sent by the temperature control unit to drive the load; The power supply circuit is used to supply power to each module and provide power input to the load; The temperature control unit is used to run the temperature controller control program according to the actual temperature, adjust the PID parameters, and control the load to linearly heat up to the specified temperature; among them, the temperature controller control program includes the self-tuning mode, the temperature control mode, and the slope temperature control mode.

6. The gradient temperature control integrated thermostat according to claim 5, characterized in that, It also includes: An indication circuit, an RS485 communication circuit, or a DeviceNet communication module; The indication circuit, the RS485 communication circuit, or the DeviceNet communication module are respectively connected to the temperature control unit, The indication circuit is used to indicate the output power supply state and the power supply state of the load; the indication circuit includes an LED indicator light, a digital tube, an organic electro-laser display, a dot matrix liquid crystal display, a field, or a cold light tube; the indication circuit includes 5 red LEDs; The RS485 communication circuit or the DeviceNet communication module is used to realize communication with the upper computer.

7. The gradient temperature control integrated thermostat according to claim 5, characterized in that The drive circuit includes a thyristor, an insulated gate bipolar transistor, silicon carbide, or a metal-oxide semiconductor field effect transistor; Among them, the drive circuit includes 4 thyristors; Alternatively, the power supply circuit includes an input filter circuit, an AC / DC module, and a low dropout linear regulator circuit; wherein, the AC / DC module is configured to convert the alternating current input from the mains into direct current 5VDC, and the low dropout linear regulator circuit is configured to provide a 3.3VDC power supply voltage for the temperature control unit.

8. The gradient temperature control integrated thermostat according to claim 5, characterized in that, It further includes a temperature sensor, the temperature sampling circuit is connected to the temperature sensor, and the temperature sensor is configured to acquire a temperature signal and transmit the temperature signal to the temperature sampling circuit; the temperature sensor includes a thermocouple; the gradient temperature control integrated thermostat is connected to 4 loads; the load includes a heating tape or a heating wire; a corresponding timer is respectively provided for each load in the temperature control unit, and the temperature of the measured point and the time slice number are acquired in the interrupt service program corresponding to the timer; the load includes an inertial load or a hysteretic load.

9. The gradient temperature control integrated temperature controller according to claim 5, characterized in that, The gradient temperature control integrated thermostat is disposed inside a preset product.

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