A constant temperature device and a control method thereof

Abstract

The present invention provides a constant temperature device and a control method thereof. The constant temperature device includes an outer tank body, an inner tank body, a master control module, a medium temperature detection module, multiple sub-control modules, and multiple constant temperature modules. The sub-control modules include a sub-controller and a heating controller. The constant temperature module includes a heating plate and a second temperature sensor. First, a heating plate temperature control value is obtained based on a first real-time temperature value of a liquid medium, a set target temperature value, and a first control algorithm, and the heating plate temperature control value is sent to each sub-controller. Then, a corresponding heating power value is obtained based on the temperature control value of each heating plate, a second real-time temperature value, and a second control algorithm. Each heating controller adjusts the heating power of each heating plate according to the heating power value, thereby achieving a more accurate constant temperature control function. The use of a zoned constant temperature control method can reduce the temperature difference between different positions of the tank body, reduce the temperature difference fluctuation of each zone, and improve control accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature control, and in particular to a constant temperature device and a control method thereof. Background Art

[0002] Semiconductors are widely used in integrated circuits, consumer electronics, communications systems, photovoltaic power generation, lighting, and high-power power conversion. In processes such as semiconductor wet etching, semiconductor devices must be immersed in the required liquid medium to carry out chemical reactions while maintaining a constant temperature. However, maintaining constant temperature in process tanks can lead to significant temperature differences between different locations within the tank, large temperature fluctuations within the same location, and low temperature control accuracy. Therefore, improvements are needed in process tank temperature control technology. Summary of the Invention

[0003] The purpose of the present invention is to solve the shortcomings of the prior art and propose a constant temperature device and a control method thereof, which adopts a zone constant temperature control strategy to improve temperature difference fluctuations, improve temperature control accuracy, and maintain constant temperature control stability.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A constant temperature device comprises an outer tank body, an inner tank body, a master control module, a medium temperature detection module, multiple groups of control modules and multiple groups of constant temperature modules.

[0006] The inner tank body is arranged inside the outer tank body, and the inner tank body is used for carrying the liquid medium.

[0007] The space between the inner tank body and the outer tank body is divided into multiple constant temperature control areas; multiple groups of constant temperature modules are arranged one by one in multiple constant temperature control areas, and each group of constant temperature modules is connected to a group of sub-control modules; multiple groups of sub-control modules are electrically connected to the main control module respectively.

[0008] The medium temperature detection module includes a first temperature sensor, which is electrically connected to the master control module. A detection end of the first temperature sensor extends into the interior of the inner tank.

[0009] Each set of constant temperature modules includes a heating plate and a second temperature sensor, and the heating plate and the second temperature sensor are arranged in the corresponding constant temperature control area.

[0010] Each group of sub-control modules includes a sub-controller and a heating controller. The sub-controller is electrically connected to the main control module, the heating controller and the corresponding second temperature sensor respectively, and the heating controller is electrically connected to the corresponding heating plate.

[0011] The first temperature sensor is used to detect the first real-time temperature value of the liquid medium and feed it back to the main control module; the main control module is used to calculate based on the first real-time temperature value, the set target temperature value and the first control algorithm to obtain the heating plate temperature control value, and send the heating plate temperature control value to multiple sub-controllers.

[0012] The second temperature sensor is used to detect the second real-time temperature value of the corresponding heating plate and feed it back to the corresponding sub-controller. The sub-controller is used to calculate according to the heating plate temperature control value, the second real-time temperature value and the second control algorithm to obtain the heating power value, and enable the heating controller to adjust the heating power of the heating plate according to the heating power value.

[0013] Preferably, the constant temperature module further includes a heat preservation layer and a protective layer, the heating plate is close to the inner tank body, the protective layer is close to the outer tank body, and the heat preservation layer is arranged between the heating plate and the protective layer.

[0014] Preferably, the insulation layer is made of rock wool or ceramic fiber, and the protective layer is made of plastic.

[0015] Preferably, the second temperature sensor is embedded in the corresponding heating plate, or is arranged between the inner tank and the heating plate, or is arranged between the heating plate and the insulation layer.

[0016] Preferably, the constant temperature device also includes a power supply module, a human-computer interaction module and an alarm module. The power supply module, the human-computer interaction module and the alarm module are electrically connected to the master control module respectively. The power supply module is used to supply power to the constant temperature device, the human-computer interaction module is used for human-computer interaction, and the alarm module is used to issue an alarm prompt signal according to the alarm control instruction sent by the master control module.

[0017] Preferably, according to the first control algorithm, the heating plate temperature control value is calculated by the following formula:

[0018]

[0019] Among them, T1 is the first real-time temperature value, T2 is the heating plate temperature control value, and A, B, C, D, and E are coefficients set according to the target temperature value.

[0020] Preferably, the second control algorithm is a position PID control algorithm; according to the second control algorithm, the heating power value is calculated by the following formula:

[0021] P=k p ×e(T)+k i ×∑e(T)+k d ×Δe(T)

[0022] Wherein, P is the heating power value, k p is the proportionality coefficient, k i is the integration coefficient, k d is the differential coefficient, e(T) is the temperature difference of the current cycle, ∑e(T) is the cumulative value of the temperature difference in multiple cycles, and Δe(T) is the temperature difference of the previous cycle.

[0023] According to another aspect of the present invention, a control method for the above-mentioned constant temperature device is provided, the control method comprising the following steps:

[0024] Step S1: detecting a first real-time temperature value of a liquid medium;

[0025] Step S2: Obtaining a heating plate temperature control value according to the first real-time temperature value, the set target temperature value, and a first control algorithm;

[0026] Step S3: detecting a second real-time temperature value of each heating plate;

[0027] Step S4: Each sub-controller obtains a corresponding heating power value based on the heating plate temperature control value, the second real-time temperature value of the corresponding heating plate and the second control algorithm, and enables the corresponding heating controller to adjust the heating power of the corresponding heating plate according to the heating power value.

[0028] Preferably, according to the first control algorithm, the heating plate temperature control value is calculated by the following formula:

[0029]

[0030] Among them, T1 is the first real-time temperature value, T2 is the heating plate temperature control value, and A, B, C, D, and E are coefficients set according to the target temperature value.

[0031] Preferably, the second control algorithm is a position PID control algorithm; according to the second control algorithm, the heating power value is calculated by the following formula:

[0032] P=k p ×e(T)+k i ×∑e(T)+k d ×Δe(T)

[0033] Wherein, P is the heating power value, k p is the proportionality coefficient, k i is the integration coefficient, k dis the differential coefficient, e(T) is the temperature difference of the current cycle, ∑e(T) is the cumulative value of the temperature difference in multiple cycles, and Δe(T) is the temperature difference of the previous cycle.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention first obtains the heating plate temperature control value based on the first real-time temperature value of the liquid medium, the set target temperature value and the first control algorithm, and sends the heating plate temperature control value to each sub-controller; then obtains the corresponding heating power value based on the temperature control value of each heating plate, the second real-time temperature value and the second control algorithm, and enables each heating controller to adjust the heating power of each heating plate according to the heating power value, thereby realizing a more accurate constant temperature control function; the use of the zoned constant temperature control method can reduce the temperature difference between different positions of the tank body, reduce the temperature difference fluctuation of each zone, and improve the control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 FIG. 1 is a schematic diagram of an electrical module of a thermostat according to an embodiment of the present invention.

[0036] Figure 2 FIG1 is a structural diagram of a tank portion of a thermostatic device according to an embodiment of the present invention at a certain viewing angle.

[0037] Figure 3 This is a structural diagram of the middle tank portion of a thermostatic device according to an embodiment of the present invention from another perspective.

[0038] Figure 4 for Figure 3 Partial cross-sectional view along AA direction.

[0039] Figure 5 This is a schematic diagram of an electrical module of a thermostat according to another embodiment of the present invention.

[0040] Figure 6 Flowchart of a method for controlling a thermostat according to an embodiment of the present invention.

[0041] In the figure, 1-outer tank body, 11-constant temperature control area, 2-inner tank body, 21-liquid medium, 3-master control module, 4-medium temperature detection module, 41-first temperature sensor, 5-sub-control module, 51-sub-controller, 52-heating controller, 6-constant temperature module, 61-heating plate, 62-second temperature sensor, 63-insulation layer, 64-protective layer, 7-power supply module, 8-human-computer interaction module, 9-alarm module. DETAILED DESCRIPTION

[0042] In order to provide a further understanding of the purpose, structure, features and functions of the present invention, the following detailed description is given in conjunction with the embodiments.

[0043] Please refer to Figure 1 and Figure 2 , Figure 1 FIG. 1 is a schematic diagram of an electrical module of a thermostat according to an embodiment of the present invention. Figure 2 The thermostat of the present invention comprises an outer tank 1, an inner tank 2, a master control module 3, a medium temperature detection module 4, multiple control modules 5, and multiple thermostat modules 6.

[0044] The inner tank body 2 is disposed inside the outer tank body 1 , and the inner tank body 2 is used to carry the liquid medium 21 .

[0045] The space between the inner tank 2 and the outer tank 1 is divided into multiple constant temperature control zones 11. Multiple sets of constant temperature modules 6 are located within these zones 11, one for each. These sets of constant temperature modules 6 are arranged around the inner tank 2 to provide zoned temperature control. Each set of constant temperature modules 6 is connected to a set of control modules 5. These control modules 5 are each electrically connected to the master control module 3.

[0046] The medium temperature detection module 4 includes a first temperature sensor 41, which is electrically connected to the master control module 3 and has a detection end extending into the interior of the inner tank 2. The first temperature sensor 41 can be disposed on a side wall or bottom wall of the inner tank 2.

[0047] Each set of constant temperature modules 6 includes a heating plate 61 and a second temperature sensor 62, which are disposed within the corresponding constant temperature control area 11. When in operation, the heating plate 61 heats the constant temperature control area 11 and transfers heat to the liquid medium 21 through heat transfer. The second temperature sensor 62 detects the temperature of the corresponding heating plate 61.

[0048] Each group of sub-control modules 5 includes a sub-controller 51 and a heating controller 52 . The sub-controller 51 is electrically connected to the main control module 3 , the heating controller 52 and the corresponding second temperature sensor 62 , respectively. The heating controller 52 is electrically connected to the corresponding heating plate 61 .

[0049] The first temperature sensor 41 is used to detect a first real-time temperature value of the liquid medium 21 and feed it back to the master control module 3. The master control module 3 is used to calculate a heating plate temperature control value based on the first real-time temperature value, a set target temperature value, and a first control algorithm, and transmit the heating plate temperature control value to the multiple sub-controllers 51. The set target temperature value is a constant temperature value that the liquid medium needs to reach according to different process requirements.

[0050] The second temperature sensor 62 is used to detect the second real-time temperature value of the corresponding heating plate 61 and feed it back to the corresponding sub-controller 51. Each sub-controller 51 is used to calculate a heating power value based on the heating plate temperature control value, the corresponding second real-time temperature value, and the second control algorithm, and to cause the corresponding heating controller 52 to adjust the heating power of the corresponding heating plate 61 based on the heating power value. Under the control of the heating controller 52, the heating plate 61 is used to heat the constant temperature control area 11 and transfer heat to the liquid medium 21 through heat transfer, so that the temperature of the liquid medium 21 meets the process requirements.

[0051] In the constant temperature device of the present invention, the heating plate temperature control value is first obtained based on the first real-time temperature value of the liquid medium 21, the set target temperature value and the first control algorithm, and the heating plate temperature control value is sent to each sub-controller 51; then, the corresponding heating power value is obtained based on the temperature control value of each heating plate, the second real-time temperature value and the second control algorithm, and each heating controller 52 adjusts the heating power of each heating plate 61 according to the heating power value, so as to achieve a more accurate constant temperature control function; and the present invention adopts a zoned constant temperature control method, which can reduce the temperature difference between different positions of the tank body, reduce the temperature difference fluctuation of each zone, and improve the control accuracy.

[0052] In practice, the first temperature sensor 41 and the second temperature sensor 62 can be commonly used temperature sensors such as thermistors and thermocouples. The heating plate 61 can be a commercially available electric heating device, with its heating output controlled by controlling its current and voltage. The master control module 3 and sub-controllers 51 can be controllers such as PLCs (Programmable Logic Controllers), and the heating controller 52 can be a relay or other device.

[0053] Please refer to Figure 3 and Figure 4 , Figure 3 This is a structural diagram of the middle tank portion of the thermostat device according to one embodiment of the present invention from another perspective. Figure 4 for Figure 3 A partial cross-sectional view along the AA direction in FIG. In a preferred embodiment of the present invention, the constant temperature module 6 further includes an insulating layer 63 and a protective layer 64. The heating plate 61 is located adjacent to the inner tank 2, and the protective layer 64 is located adjacent to the outer tank 1. The insulating layer 63 is disposed between the heating plate 61 and the protective layer 64. The insulating layer 63 provides insulation and reduces heat loss. The protective layer 64 protects the insulating layer 63, the heating plate 61, and the second temperature sensor 62, minimizing component damage and extending the device's service life.

[0054] In application, the insulation layer 63 can be made of materials such as rock wool or ceramic fiber, and the protective layer 64 can be made of materials such as plastic, such as PVDF (polyvinylidene fluoride), which has excellent physical and chemical properties, such as high temperature stability, corrosion resistance, high weather resistance, etc., and exhibits good electrical insulation performance, mechanical strength and plasticity. It can be used as the protective layer 64 to improve the comprehensive performance of the constant temperature module 6.

[0055] In a preferred embodiment of the present invention, the second temperature sensor 62 can be embedded in the corresponding heating plate 61, or arranged between the inner tank 2 and the heating plate 61, or arranged between the heating plate 61 and the insulation layer 63. Figure 4 In one embodiment, the second temperature sensor 62 is embedded in the corresponding heating plate 61 , and is used to detect the second real-time temperature value of the corresponding heating plate 61 and feed it back to the corresponding sub-controller 51 .

[0056] See Figure 5 , Figure 5 This is a schematic diagram of the electrical module of a thermostat according to another embodiment of the present invention. In a preferred embodiment of the present invention, the thermostat further comprises a power supply module 7, a human-computer interaction module 8 and an alarm module 9. The power supply module 7, the human-computer interaction module 8 and the alarm module 9 are electrically connected to the master control module 3 respectively. The power supply module 7 is used to supply power to the thermostat, and the human-computer interaction module 8 is used for human-computer interaction. The human-computer interaction module 8 can be used to display the working status of the thermostat and to allow operators to input target temperature values, algorithm parameters, etc. The alarm module 9 is used to issue an alarm prompt signal according to the alarm control instruction sent by the master control module 3. The alarm module 9 can adopt commercially available sound and light alarms and other products. For example, when the first real-time temperature value exceeds the set temperature threshold, the master control module 3 can control the alarm module 9 to issue an sound and light alarm prompt signal.

[0057] In a preferred embodiment of the present invention, according to the first control algorithm, the temperature control value of the heating plate is calculated by the following formula:

[0058]

[0059] Among them, T1 is the first real-time temperature value, T2 is the heating plate temperature control value, and A, B, C, D, and E are coefficients set according to the target temperature value.

[0060] In a preferred embodiment of the present invention, the second control algorithm is a position PID control algorithm. According to the second control algorithm, the heating power value is calculated by the following formula:

[0061] P=k p ×e(T)+k i ×∑e(T)+k d ×Δe(T)

[0062] Where P is the heating power value, k p is the proportionality coefficient, k i is the integration coefficient, k d is the differential coefficient, e(T) is the temperature difference of the current cycle, ∑e(T) is the cumulative value of the temperature difference in multiple cycles, and Δe(T) is the temperature difference of the previous cycle.

[0063] The use of PID control algorithm for constant temperature control can achieve more accurate constant temperature control function; and the use of partition constant temperature control method can reduce the temperature difference in different positions of the tank body, reduce the temperature difference fluctuation of each partition, and improve control accuracy.

[0064] According to another aspect of the present invention, a method for controlling the above-mentioned constant temperature device is provided. Figure 6 This is a flow chart of a method for controlling a thermostat according to an embodiment of the present invention. The method comprises the following steps:

[0065] Step S1: Detecting a first real-time temperature value of the liquid medium 21 ; this step can be implemented using the first temperature sensor 41 in the above-mentioned constant temperature device. The first temperature sensor 41 detects the first real-time temperature value of the liquid medium 21 and feeds it back to the master control module 3 .

[0066] Step S2: Obtaining a heating plate temperature control value according to the first real-time temperature value, the set target temperature value, and the first control algorithm; this step can be implemented using the master control module 3 .

[0067] Step S3: Detect the second real-time temperature value of each heating plate 61; this step can be implemented using the second temperature sensor 62 in the above-mentioned constant temperature device. The second temperature sensor 62 detects the second real-time temperature value of the corresponding heating plate 61 and feeds it back to the corresponding sub-controller 51.

[0068] Step S4: Each sub-controller 51 obtains the corresponding heating power value based on the heating plate temperature control value, the second real-time temperature value of the corresponding heating plate 61 and the second control algorithm, and enables the corresponding heating controller 52 to adjust the heating power of the corresponding heating plate 61 according to the heating power value.

[0069] Preferably, according to the first control algorithm, the temperature control value of the heating plate is calculated by the following formula:

[0070]

[0071] Among them, T1 is the first real-time temperature value, T2 is the heating plate temperature control value, and A, B, C, D, and E are coefficients set according to the target temperature value.

[0072] In one embodiment, the target temperature is set to 60°C. Based on the target temperature, the five coefficients are: A = 0.000001253968254, B = -0.000334206349207, C = 0.031946031746046, D = -0.264198412699012, E = 16.0833333333342257, and the calculation formula of the heating plate temperature control value T2 is:

[0073]

[0074] In a preferred embodiment of the present invention, the second control algorithm is a position PID control algorithm; according to the second control algorithm, the heating power value is calculated by the following formula:

[0075] P=k p ×e(T)+k i ×∑e(T)+k d ×Δe(T)

[0076] Where P is the heating power value, k p is the proportionality coefficient, k i is the integration coefficient, k d is the differential coefficient, e(T) is the temperature difference of the current cycle, ∑e(T) is the cumulative value of the temperature difference in multiple cycles, and Δe(T) is the temperature difference of the previous cycle.

[0077] The above-mentioned constant temperature device and constant temperature control method have been tested in actual applications. Under different set target temperature values ​​(for example, 40°C, 60°C, and 80°C), the constant temperature control is stable, and the temperature difference (temperature fluctuation) between the actual temperature of each partition and the set temperature can always be controlled within the allowable temperature difference range, for example, ±0.3°C, which can meet the application requirements of processes such as semiconductor etching.

[0078] In one embodiment, the target temperature is set at 60°C. A total of 16 thermostatic modules are provided around and on the bottom of the inner tank. The thermostatic control results of the thermostatic device within 5 hours are recorded in Table 1 below:

[0079] Table 1: Constant temperature device test temperature record

[0080] time Detection 1 Detection 2 Detection 3 Detection 4 Detection 5 Detection 6 Detection 7 Detection 8 0 hours 60.26 60.34 60.13 60.22 60.59 60.32 60.39 60.39 0.5 hours 60.17 60.33 60.03 60.13 60.44 60.29 60.26 60.29 1 hour 60.32 60.30 60.07 59.97 60.41 60.28 60.25 60.34 1.5 hours 60.37 60.27 60.02 60.00 60.35 60.32 60.18 60.32 2 hours 60.36 60.37 59.84 60.00 60.30 60.39 60.19 60.43 2.5 hours 60.26 60.42 60.15 60.05 60.33 60.33 60.32 60.36 3 hours 60.30 60.30 59.92 60.06 60.27 60.31 60.31 60.42 3.5 hours 60.30 60.23 60.14 60.08 60.25 60.31 60.24 60.48 4 hours 60.28 60.31 60.09 59.94 60.25 60.25 60.23 60.42 4.5 hours 60.17 60.28 60.02 60.00 60.16 60.20 60.96 60.36 5 hours 60.28 60.26 60.08 59.95 60.23 60.18 60.21 60.42 time Detection 9 Detection 10 Detection 11 Detection 12 Detection 13 Detection 14 Detection 15 Detection 16 0 hours 59.94 60.19 60.29 60.06 60.21 60.06 60.28 60.21 0.5 hours 59.96 60.17 60.26 59.98 60.11 60.01 60.35 59.95 1 hour 60.02 60.25 60.23 60.01 60.22 59.95 60.27 60.11 1.5 hours 60.04 60.21 60.22 59.97 60.14 59.99 60.24 60.03 2 hours 60.00 60.23 60.21 60.01 60.17 60.06 60.26 60.06 2.5 hours 60.04 60.23 60.26 60.06 60.09 60.04 60.26 60.14 3 hours 59.94 60.18 60.28 60.05 60.07 59.99 60.28 60.07 3.5 hours 60.00 60.13 60.21 60.11 60.02 59.93 60.28 60.18 4 hours 59.93 60.14 60.31 60.07 60.00 59.93 60.26 60.08 4.5 hours 60.00 60.14 60.24 60.08 59.98 59.93 60.28 60.07 5 hours 59.94 60.17 60.28 60.10 60.05 59.96 60.24 60.01

[0081] It can be seen from the experimental data that the constant temperature device and control method of the present invention can achieve constant temperature stable control, control the long-term temperature difference fluctuation of each constant temperature control area within an allowable range, ensure the temperature control accuracy, and meet the application requirements of processes such as semiconductor etching.

[0082] In summary, the present invention provides a constant temperature device and a constant temperature control method, which first calculates based on the first real-time temperature value of the liquid medium, the set target temperature value and the first control algorithm to obtain the temperature control value of the heating plate, and sends the temperature control value of the heating plate to each sub-controller; then calculates based on the temperature control value of each heating plate, the second real-time temperature value and the second control algorithm to obtain the corresponding heating power value, and enables each heating controller to adjust the heating power of each heating plate according to the heating power value, thereby realizing a more accurate constant temperature control function; adopting the zoned constant temperature control method can reduce the temperature difference between different positions of the tank body, reduce the temperature difference fluctuation of each zone, and improve the control accuracy.

[0083] The present invention has been described with reference to the above embodiments. However, the above embodiments are merely exemplary embodiments of the present invention. It should be noted that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and improvements that do not depart from the spirit and scope of the present invention are intended to be protected by the present invention.

Claims

1. A constant temperature device, characterized in that: It includes an outer tank body, an inner tank body, a master control module, a medium temperature detection module, multiple groups of control modules and multiple groups of constant temperature modules; The inner tank body is arranged inside the outer tank body, and the inner tank body is used to carry the liquid medium; The space between the inner tank body and the outer tank body is divided into multiple constant temperature control areas; multiple groups of constant temperature modules are arranged in a one-to-one correspondence in the multiple constant temperature control areas, and each group of constant temperature modules is connected to a group of sub-control modules; and multiple groups of sub-control modules are respectively electrically connected to the master control module; The medium temperature detection module includes a first temperature sensor, the first temperature sensor is electrically connected to the master control module, and a detection end of the first temperature sensor extends into the interior of the inner tank; Each set of constant temperature modules includes a heating plate and a second temperature sensor, and the heating plate and the second temperature sensor are arranged in the corresponding constant temperature control area; Each group of sub-control modules includes a sub-controller and a heating controller, wherein the sub-controller is electrically connected to the main control module, the heating controller and the corresponding second temperature sensor respectively, and the heating controller is electrically connected to the corresponding heating plate; The first temperature sensor is used to detect a first real-time temperature value of the liquid medium and feed it back to the master control module; The master control module is configured to obtain a heating plate temperature control value based on the first real-time temperature value, the set target temperature value, and a first control algorithm, and send the heating plate temperature control value to multiple sub-controllers; According to the first control algorithm, the heating plate temperature control value is calculated by the following formula: in, is the first real-time temperature value, is the heating plate temperature control value, A 、 B 、 C 、 D 、 E are coefficients set according to the target temperature value; The second temperature sensor is used to detect a second real-time temperature value of the corresponding heating plate and feed it back to the corresponding sub-controller, the sub-controller is used to calculate according to the heating plate temperature control value, the second real-time temperature value and a second control algorithm to obtain a heating power value, and enable the heating controller to adjust the heating power of the heating plate according to the heating power value; The second control algorithm is a position PID control algorithm; according to the second control algorithm, the heating power value is calculated by the following formula: in, is the heating power value, is the proportionality coefficient, is the integration coefficient, is the differential coefficient, is the temperature difference of the current cycle, is the cumulative value of the temperature difference in multiple cycles, is the temperature difference of the previous cycle.

2. The thermostat according to claim 1, wherein: The constant temperature module further includes a heat preservation layer and a protective layer. The heating plate is close to the inner tank body, the protective layer is close to the outer tank body, and the heat preservation layer is arranged between the heating plate and the protective layer.

3. The thermostat according to claim 2, wherein: The thermal insulation layer is made of rock wool or ceramic fiber, and the protective layer is made of plastic.

4. The thermostat according to claim 2, wherein: The second temperature sensor is embedded in the corresponding heating plate, or is arranged between the inner tank and the heating plate, or is arranged between the heating plate and the insulation layer.

5. The thermostat according to claim 1, wherein: The constant temperature device also includes a power supply module, a human-computer interaction module and an alarm module. The power supply module, the human-computer interaction module and the alarm module are respectively electrically connected to the master control module. The power supply module is used to supply power to the constant temperature device, the human-computer interaction module is used to perform human-computer interaction, and the alarm module is used to issue an alarm prompt signal according to the alarm control instruction sent by the master control module.

6. A method for controlling a constant temperature device, characterized in that: The thermostat is a thermostat according to any one of claims 1 to 5, and the control method comprises the following steps: Step S1: detecting a first real-time temperature value of a liquid medium; Step S2: Obtaining a heating plate temperature control value according to the first real-time temperature value, the set target temperature value, and a first control algorithm; Step S3: detecting a second real-time temperature value of each heating plate; Step S4: Each sub-controller obtains a corresponding heating power value based on the heating plate temperature control value, the second real-time temperature value of the corresponding heating plate and the second control algorithm, and enables the corresponding heating controller to adjust the heating power of the corresponding heating plate according to the heating power value.

7. The control method according to claim 6, wherein: According to the first control algorithm, the heating plate temperature control value is calculated by the following formula: in, is the first real-time temperature value, is the heating plate temperature control value, A 、 B 、 C 、 D 、 E are all coefficients set according to the target temperature value.

8. The control method according to claim 6, wherein: The second control algorithm is a position PID control algorithm; according to the second control algorithm, the heating power value is calculated by the following formula: in, is the heating power value, is the proportionality coefficient, is the integration coefficient, is the differential coefficient, is the temperature difference of the current cycle, is the cumulative value of the temperature difference in multiple cycles, is the temperature difference of the previous cycle.

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