Constant temperature control system and method for weighing device

Abstract

The invention provides a constant-temperature control system and method for a weighing device, and relates to the technical field of measuring instruments, and the system comprises a constant-temperature box, a heating element, a temperature sensor, a high-thermal-conductivity connecting material, a thermal insulation material, and a control chip. The control method comprises the steps of detecting temperature in real time through the temperature sensor, transmitting a temperature signal to the control chip for processing, calculating temperature deviation, calculating control output by adopting a PI control algorithm, generating a PWM signal to control heating power, forming closed-loop control and the like. Direct thermal coupling of the heating film, the heated object and the temperature sensor is achieved through the high-thermal-conductivity connecting material, high-precision temperature control of + / -0.02 DEG C can be achieved in combination with the PI control algorithm, and the influence of temperature drift on high-precision measurement is effectively eliminated.

Description

Technical Field

[0001] This invention relates to the field of measuring instrument technology, specifically to a constant temperature control system and method for a weighing device. Background Technology

[0002] In high-precision weighing systems, measurement accuracy is a key indicator for evaluating system performance. Taking a 5-digit weighing system as an example, with a full-scale range of 200,000 grams and a resolution of one part in twenty million, the system requires extremely high precision. Under such high precision requirements, even the slightest disturbance in the system can significantly affect the measurement results.

[0003] Temperature variations have a particularly pronounced impact on high-precision weighing systems. Key electronic components in these systems, such as precision operational amplifiers, high-precision AD samplers, and reference voltage sources, all exhibit unavoidable temperature drift. Even highly stable components with a temperature stability of 2 ppm (parts per million) will still experience a change in performance parameters of 2 ppm when the ambient temperature changes by 1 °C. For a weighing system with a resolution of 1 / 20 million, this temperature drift can lead to data variations of up to 40 divisions (40 days), severely affecting measurement accuracy and system stability.

[0004] Currently, the industry mainly adopts two technical approaches for temperature control of high-precision measurement systems: one is to construct a large-scale constant-temperature environment, placing the entire measurement system in a constant-temperature chamber or box; the other is to use a complex multi-channel constant-temperature control system, achieving precise temperature control through multi-layer insulation structures and multi-point temperature monitoring. However, these existing technical solutions have obvious limitations.

[0005] Most existing temperature control solutions adopt an environmental temperature control approach, controlling the ambient temperature surrounding the measurement system rather than directly controlling the temperature of the key components themselves. This indirect control method suffers from problems such as long heat conduction paths, slow response speeds, and poor temperature consistency. Because there are thermal resistance and thermal capacitance between the ambient temperature control point and the key components requiring temperature control, the stability of the ambient temperature cannot completely guarantee the stability of the key component's temperature. Especially when the ambient temperature changes, there are time and temperature differences in the temperature response of components at different locations, affecting the overall temperature control performance.

[0006] Furthermore, existing technical solutions also have shortcomings in terms of control algorithms. Although traditional PID control algorithms are widely used, when dealing with controlled objects such as temperature control that have large inertia and large lag, they often suffer from problems such as large overshoot, long settling time, and low steady-state accuracy, making it difficult to meet the stringent temperature stability requirements of high-precision weighing systems.

[0007] Chinese patent application CN111256793A discloses an environmentally friendly, high-precision constant temperature and humidity weighing device. It discloses a five-sided heat exchange constant temperature control technology solution using water as the heat conduction medium. The constant temperature and humidity control of the overall environment inside the operating box is achieved through a water circulation system, heating coils and circulating fans. It achieves the technical effect of building a stable measurement environment and improving weighing accuracy. However, it still suffers from large equipment size, high energy consumption, high cost and slow response speed, making it difficult to meet the requirements of equipment miniaturization and cost control in industrial production.

[0008] Chinese patent application CN114779847A discloses a constant temperature system for a portable relative gravimeter, which discloses a precision temperature control technology scheme with a three-way constant temperature structure wrapped in layers. It achieves high-precision constant temperature protection for the gravity sensor through multi-layer aerogel insulation, multi-point temperature monitoring and segmented PID-Smith control algorithm, meeting the requirements of low power consumption, light weight and high stability of portable gravimeter. However, the system structure is complex, requiring multiple temperature sensors, multiple sets of control circuits and complex coordination control algorithms, which not only increases the system cost, but also increases the failure rate and maintenance difficulty. Summary of the Invention

[0009] The purpose of this invention is to provide a constant temperature control system and method for weighing devices that is simple in structure, cost-controllable, fast in response, and capable of achieving high-precision temperature control.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a constant temperature control system for a weighing device, comprising a constant temperature chamber, a heating element, a temperature sensor, a high thermal conductivity connecting material, a heat insulation material, and a temperature control board, wherein the constant temperature chamber is a box-shaped structure made of a metal plate; The bottom end of the heating element is provided with foam, the top end of the heating element is tightly attached to the bottom surface of the constant temperature chamber, the bottom end of the high thermal conductivity connecting material is tightly attached to the bottom surface of the constant temperature chamber, and the temperature sensor is disposed between the high thermal conductivity connecting material and the bottom surface of the constant temperature chamber; the heat insulation material covers the surface of the non-connected heating element of the constant temperature heating chamber; the temperature control board is electrically connected to the temperature sensor and the heating element respectively.

[0011] Furthermore: the heating element includes a heating film, or includes a heating film and a semiconductor cooling chip.

[0012] Furthermore, the temperature sensor includes a PT1000 sensor or a PTC sensor.

[0013] Furthermore: the temperature control board includes a temperature sampling circuit, a microcontroller, and a power drive circuit connected in sequence; The temperature sampling circuit samples and converts the output signal of the temperature sensor. The microcontroller processes the temperature sampling data and executes the control algorithm. It controls the power drive circuit according to the temperature sampling data. The power drive circuit drives the heating element according to the control signal of the microcontroller.

[0014] Furthermore, the power drive circuit adopts PWM control, which controls the heating power of the heating element by adjusting the duty cycle of the PWM signal.

[0015] Furthermore, the microcontroller employs a PI control algorithm to optimize the stability and speed of temperature control by adjusting the proportional gain and integral gain parameters.

[0016] Furthermore: the constant temperature box is a box-shaped structure made of aluminum plate, and the high thermal conductivity connecting material is thermally conductive silicone grease or thermally conductive silicone.

[0017] Furthermore, the temperature control accuracy of the system is ±0.02℃, and the temperature fluctuation range of the constant temperature chamber is ±0.02℃.

[0018] The temperature control method based on the above-mentioned constant temperature control system for the weighing device includes the following steps: S1: The temperature of the constant temperature chamber is detected in real time by a temperature sensor; S2: Transmit the detected temperature signal to the temperature control board for processing; S3: The temperature control board compares the detected temperature with the set target temperature and calculates the temperature deviation; S4: Based on the temperature deviation, the required control output is calculated using a PI control algorithm; S5: Generates a PWM signal based on the control output, and controls the heating power of the heating element through the temperature control board; S6: Repeat steps S1 to S5 to form a closed-loop control until the temperature of the constant temperature chamber stabilizes within the target temperature range.

[0019] Furthermore, in step S4, the PI control algorithm simplifies the temperature control system into a first-order system for processing, and adjusts the proportional gain parameter and integral gain parameter to make the stability and response speed of the temperature controller meet the usage requirements.

[0020] Compared with the prior art, the present invention has the following advantages: This invention provides a technical solution that uses a high thermal conductivity connecting material to connect the key components to be measured to the metal plate of the constant temperature chamber, thus transferring heat and solving the problem of temperature inconsistency between the control point and the controlled object in traditional environmental temperature control methods. Due to the short heat conduction path, low thermal resistance, and high heat transfer efficiency, it ensures good temperature consistency between the electronic components and the temperature control point, avoiding temperature lag and differences caused by indirect control, thereby effectively eliminating the impact of component temperature drift on the high-precision weighing system.

[0021] This invention employs a PI control algorithm and simplifies the temperature control system to a first-order system, offering better stability and practicality compared to traditional complex control algorithms. By adjusting the proportional gain Kp and integral gain Ki parameters to optimize the open-loop gain, and based on the principle of automatic control that the error is the reciprocal of the open-loop gain (higher open-loop gain results in smaller error), high-precision temperature control of less than ±0.02℃ is achieved, meeting the stringent temperature stability requirements of high-precision weighing systems.

[0022] This invention employs a single constant temperature control structure, avoiding the complexity of multi-channel constant temperature systems. The system structure is simple and the cost is controllable. Compared to existing technologies that require multiple temperature sensors, multiple control circuits, and complex coordination algorithms, this invention requires only a single temperature sensor and a simplified control circuit, significantly reducing system cost and maintenance difficulty while ensuring system stability and reliability.

[0023] This invention employs a PWM-controlled heating element power solution, which offers fast response and high control precision. The heating element is directly attached to the surface of the constant-temperature metal plate, resulting in high heat transfer efficiency and rapid response to temperature changes. This ensures that the temperature fluctuation of the constant-temperature metal plate remains within ±0.02℃, thereby guaranteeing that the temperature of key components is controlled within ±0.02℃, effectively improving the measurement accuracy and long-term stability of the high-precision weighing system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a constant temperature control system for a weighing device in one embodiment of the present invention; Figure 2 This is a flowchart illustrating a temperature control method for a constant temperature control system of a weighing device according to one embodiment of the present invention. Figure 3 This is a schematic flowchart illustrating the constant temperature control principle of the control system in one embodiment of the present invention; Figure 4 This is a schematic circuit diagram of a temperature sensor in one embodiment of the present invention; Figure 5 This is a schematic diagram of the power supply circuit for the heating film in one embodiment of the present invention; Figure 6This is a schematic diagram of a microcontroller control circuit in one embodiment of the present invention; In the picture: 1. Constant temperature chamber; 2. Heating element; 3. Temperature sensor; 4. High thermal conductivity connecting material; 5. Thermal insulation material; 6. Key components. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that Kp is the proportional gain parameter and Ki is the integral gain parameter. By adjusting the proportional gain parameter Kp and the integral gain parameter Ki, the stability and response speed of the temperature controller can meet the usage requirements.

[0027] It should be noted that the constant temperature system and weighing system provided by this invention are connected separately and are used in conjunction with the weighing system.

[0028] Example 1 like Figure 1 The image shows a constant temperature control system for a weighing device according to an embodiment of the present invention, comprising a constant temperature chamber 1, a heating element 2, a temperature sensor 3, a high thermal conductivity connecting material 4, a heat insulation material 5, and a temperature control board. Figure 1 It also includes a key component 6 that requires constant temperature protection. The core inventive concept of this system is to achieve direct thermal coupling between the key component 6 requiring constant temperature protection and the constant temperature chamber 1 through a high thermal conductivity material, and to achieve high-precision temperature control by using a closed-loop control algorithm.

[0029] The constant temperature chamber 1 is a box-shaped structure made of metal plates, preferably aluminum plates with good thermal conductivity. Aluminum plates have excellent thermal conductivity, which can quickly and evenly conduct heat, ensuring the uniformity of temperature distribution throughout the heating chamber. The design dimensions of the constant temperature chamber 1 are determined according to the dimensions of the board containing the key component 6 that needs constant temperature protection. Typically, the bottom area of ​​the chamber is slightly larger than the dimensions of the board containing the key component 6 to be kept at a constant temperature, to ensure sufficient thermal contact.

[0030] The top of the heating element 2 is fitted tightly against the bottom surface of the constant temperature chamber 1 to provide heat to the chamber. Foam is provided at the bottom of the heating element 2 to prevent heat from escaping to the outside. The heating element 2 can be a heating film; see [reference needed]. Figure 5This is a schematic diagram of the power supply circuit for the heating film. The voltage on the heating film is controlled via PWM to achieve constant temperature. The U5 chip drives Q2. By providing different pulse width control signals to U5, different voltages can be applied to the heating film. Based on the principle that power equals the square of the voltage divided by the resistance, the power of the heating film can be changed.

[0031] It should be noted that, Figure 5 The specific working principle of voltage control via PWM is as follows: because Figure 5 The circuit in the middle is a BUCK circuit, and Q2 is a switch. If Q2 is turned on, the output voltage is the same as the input voltage. If its on time is half, the output voltage is about half of the input voltage. Therefore, the lower the duty cycle, the lower the output voltage. The duty cycle can be adjusted by adjusting the on time of Q2, thereby controlling the output voltage.

[0032] The specific working principle of providing different control signals to U5 is as follows: Q2 uses NMOS, and U5 completes the bootstrap function. When driving NMOS, its source voltage will rise after being turned on. Therefore, in order for Q2 to work well, the gate voltage needs to be raised higher than the drain voltage. So a bootstrap circuit is needed to drive Q2.

[0033] The heating film is characterized by its thinness, uniform heating, and fast response, allowing it to adhere tightly to the aluminum plate surface for efficient heat transfer. The power selection of the heating film needs to be determined based on the heat dissipation conditions of the actual application environment and the required temperature control accuracy. In some applications, the heating element 2 may also include a thermoelectric cooler. The thermoelectric cooler enables bidirectional temperature regulation, allowing for both heating and cooling, thus achieving a wider range of temperature control, particularly suitable for applications requiring operation below ambient temperature.

[0034] Temperature sensor 3 is positioned between the high thermal conductivity connecting material 4 and the bottom surface of the constant temperature chamber 1 to accurately detect the temperature of the constant temperature chamber 1. A PT1000 temperature sensor or a PTC sensor is preferably used.

[0035] like Figure 4 The diagram shown is a schematic of the circuit for temperature sensor 3. Figure 4 Temperature sensor 3 is a PT1000, a high-precision and stable platinum resistance temperature sensor. Its resistance is linearly related to temperature, facilitating signal processing and temperature calculation. The PT1000 temperature sensor is powered by a 1mA constant current source. The voltage change across the sensor reflects the temperature change. This voltage signal is amplified by an operational amplifier and then input to the temperature control board for control calculations.

[0036] A high thermal conductivity connecting material 4 is disposed at the top of the bottom surface of the constant temperature chamber 1 to achieve efficient heat conduction between the critical component 6 protected by constant temperature and the constant temperature chamber 1. The selected high thermal conductivity connecting material 4 has a thermal conductivity greater than 1 W / m*K. The high thermal conductivity connecting material 4 can be thermally conductive grease or thermally conductive silicone. These materials have excellent thermal conductivity and good gap-filling ability, which can fill the tiny gaps between the critical component 6 protected by constant temperature and the constant temperature chamber 1, eliminate air gaps, and achieve good thermal contact. The thermal conductivity of thermally conductive grease is typically in the range of 0.8-8 W / mK, while thermally conductive silicone, in addition to good thermal conductivity, also has a certain mechanical strength, making it easy to assemble and use.

[0037] The temperature control board is placed on the outside of the constant temperature chamber 1 (not shown in the figure). The temperature control board is electrically connected to the temperature sensor 3 and the heating element 2, and controls the temperature of the entire constant temperature control system. In a high-precision weighing system, the critical component 6 protected by constant temperature typically includes temperature-sensitive components such as sophisticated analog circuits, high-precision AD samplers, and reference voltage sources. Through the high thermal conductivity connecting material 4, the critical component 6 protected by constant temperature can maintain good thermal coupling with the constant temperature chamber 1, ensuring temperature consistency.

[0038] The insulation material 5 wraps around the surface of the non-connected heating elements of the constant temperature chamber 1 to reduce heat loss to the outside, improve temperature control efficiency, and reduce power consumption. The insulation material 5 can be a low thermal conductivity material, such as polyurethane foam or aerogel. The thickness of the insulation material needs to be designed according to the actual heat dissipation conditions and power consumption requirements, ensuring good insulation performance while avoiding excessive increase in system volume.

[0039] The temperature control board is electrically connected to the temperature sensor 3 and the heating element 2 to achieve closed-loop regulation of temperature detection and heating control. The temperature control board includes a microcontroller or other MCU with sufficient computing power.

[0040] In one specific implementation of this embodiment, such as Figure 6 The diagram shown is a schematic of a microcontroller control circuit. It uses the temperature collected from the PT1000 and the desired target temperature to perform PI control. By changing the PWM output, the power of the heating film is changed to achieve the purpose of constant temperature.

[0041] It should be noted that the entire control system, from the heating film to the PT1000, is a second-order system. However, since the PT1000 is directly attached to the metal plate and has a very small heat capacity, it can be equivalent to a first-order system. Therefore, in the control, a PI converter is used to compensate for the gain at the low frequency end, and temperature stability and speed are adjusted by changing Kp and Ki to meet the requirements. According to the principle of automatic control, the error is the reciprocal of the open-loop gain, so the higher the open-loop gain, the smaller the error. By modulating the open-loop gain, constant temperature control can be achieved.

[0042] In one specific implementation of this embodiment, such as Figure 3 The diagram shown illustrates the flow chart of the constant temperature control principle of the control system. The constant temperature control circuit includes a temperature sampling circuit, a microcontroller, and a power drive circuit connected in sequence. The temperature sampling circuit is responsible for sampling and converting the output signal of the PT1000 temperature sensor, typically using a high-precision AD sampler to ensure the accuracy of temperature detection. The microcontroller processes the temperature sampling data and executes the control algorithm, controlling the power drive circuit based on the temperature sampling data. The power drive circuit drives the heating element 2 according to the control signal from the microcontroller, controlling the heating power.

[0043] The power drive circuit adopts PWM control, which controls the heating power of heating element 2 by adjusting the duty cycle of the PWM signal. PWM control has the advantages of high control accuracy, fast response speed and high efficiency. The power drive circuit usually uses MOSFET as a switching device, and controls the on and off of the MOSFET by the PWM signal, thereby controlling the current flowing through heating element 2.

[0044] The microcontroller employs a PI control algorithm, optimizing temperature control stability by adjusting the proportional gain Kp and integral gain Ki parameters. In practical applications, because the PT1000 sensor is directly attached to the constant temperature chamber 1 and uses a high thermal conductivity material, and the PT1000 has a relatively small heat capacity, the entire temperature control system can be simplified as a first-order system. By adjusting the Kp and Ki parameters, the open-loop gain is made to cross over with a first-order slope. According to the principles of automatic control, the error is the reciprocal of the open-loop gain; the higher the open-loop gain, the smaller the steady-state error, thus achieving high-precision temperature control.

[0045] It should be noted that, as Figure 4-6 As shown, the specific process of control achieved by the circuit in this invention is as follows: U3A generates a constant current of 1mA. This current passes through PT1000. The resistance of PT1000 is related to temperature, so after the constant current passes through PT1000, the voltage on it is related to temperature. This voltage is differentially amplified by the operational amplifier U3B and then enters the software processing inside the MCU. It first undergoes software filtering, and then the filtered temperature value is entered into the PI control algorithm. The output of the PI control algorithm generates a PWM signal. This PWM signal is used to drive U5, thereby controlling the conduction time of Q2.

[0046] The working principle of this embodiment is as follows: The constant temperature control system of the weighing device in this embodiment is based on the closed-loop temperature control principle and the high thermal conductivity principle. It achieves high-precision temperature control through accurate temperature detection, intelligent control algorithm and efficient heat conduction, effectively eliminating measurement errors caused by temperature drift of electronic components.

[0047] After the system starts up, the PT1000 temperature sensor begins to monitor the temperature status of the constant temperature chamber 1 in real time. The PT1000 sensor is powered by a 1mA constant current source, and its resistance changes linearly with temperature. When the temperature changes, the voltage across the sensor also changes accordingly. This tiny voltage change signal is amplified by a high-precision operational amplifier and then sent to the MCU for digital processing to obtain an accurate temperature value.

[0048] After receiving the digitized temperature signal, the microcontroller compares it with the preset target temperature and calculates the current temperature deviation. Based on this deviation, the microcontroller runs a PI control algorithm for control calculations. The proportional element in the PI control algorithm can quickly respond to temperature deviations, while the integral element can eliminate the steady-state error of the system. By appropriately adjusting the proportional gain Kp and integral gain Ki parameters, the system can avoid overshoot while ensuring a fast response, achieving stable temperature control. By adjusting the Kp and Ki parameters, the crossover frequency and slope are controlled. According to the principle of automatic control, the error is the reciprocal of the open-loop gain; the higher the open-loop gain, the smaller the steady-state error, thus achieving high-precision temperature control.

[0049] The output of the control algorithm is converted into a PWM control signal, the duty cycle of which directly determines the heating power of heating element 2. When the detected temperature is lower than the target temperature, the control algorithm outputs a larger PWM duty cycle, enabling heating element 2 to provide more heat; when the detected temperature approaches or reaches the target temperature, the PWM duty cycle decreases accordingly, reducing the heating power; when the detected temperature is higher than the target temperature, the PWM duty cycle further decreases or even becomes zero, stopping heating or activating the cooling function if a semiconductor cooling chip is provided.

[0050] After receiving the PWM control signal, heating element 2 operates according to the corresponding duty cycle, and the generated heat is transferred to the constant temperature chamber 1 through close contact. Since the constant temperature chamber 1 is made of aluminum plate with excellent thermal conductivity, the heat can spread quickly and evenly throughout the entire heating chamber, ensuring the temperature consistency of each part of the heating chamber.

[0051] The critical component 6, protected by constant temperature, is in close contact with the top surface of the constant temperature chamber 1 via a high thermal conductivity connecting material 4. The high thermal conductivity connecting material 4 fills the tiny gaps between the chip and the heating chamber, eliminating air gaps and establishing a good heat conduction channel. Due to its extremely low thermal resistance, temperature changes in the constant temperature chamber 1 can be quickly and accurately transmitted to the critical component 6, ensuring that the chip temperature and the heating chamber temperature remain highly consistent.

[0052] The insulation material 5 surrounding the constant temperature chamber 1 plays a crucial role in heat preservation, effectively reducing heat loss to the external environment. This not only improves the system's heating efficiency and reduces power consumption, but also minimizes the interference of external temperature changes on the system, enhancing the stability of temperature control.

[0053] The entire control process forms a complete closed-loop control system: temperature sensor 3 detects → signal amplification and conversion → control algorithm calculation → PWM power adjustment → heat transfer → temperature change → re-detection. This closed-loop control process is continuous, with an extremely short response time, enabling timely detection and correction of temperature deviations.

[0054] Thanks to its high thermal conductivity design and simplified first-order system control model, the entire temperature control system features fast response and high control accuracy. The PT1000 sensor is directly embedded in the connecting material between the critical component 6, which is protected by constant temperature, and the constant temperature chamber 1. This accurately reflects the actual temperature of the critical component 6, avoiding control deviations caused by the inconsistency between the sensor position and the controlled object position in traditional environmental temperature control methods.

[0055] Through this working principle, the system can control the temperature fluctuation of the constant temperature chamber 1 within a very small range of less than ±0.02℃, thereby ensuring that the temperature fluctuation of the critical component 6 under constant temperature protection is less than ±0.02℃. This high-precision temperature control effectively eliminates the temperature drift of various temperature-sensitive components in the protected critical component 6, significantly improving the measurement accuracy and long-term stability of the weighing device. Even under conditions of significant changes in the external ambient temperature, the system can quickly adjust and maintain a stable operating temperature, ensuring the reliable operation of the measuring device.

[0056] Example 2 like Figure 2 As shown, a temperature control method for a constant temperature control system of a weighing device, provided in an embodiment of the present invention, includes the following steps: S1: The temperature of the constant temperature chamber 1 is detected in real time by temperature sensor 3, providing accurate temperature feedback information for the entire control system, which is the basis for realizing closed-loop control. S2: The detected temperature signal is transmitted to the temperature control board for processing, converting the analog temperature signal into a digital signal to prepare data for subsequent digital control processing; S3: The temperature control board compares the detected temperature with the set target temperature, calculates the temperature deviation, determines the gap between the current temperature state and the desired temperature state, and provides a decision basis for the control algorithm; S4: Based on the temperature deviation, the required control output is calculated using a PI control algorithm. The temperature deviation is then converted into specific control commands through an intelligent algorithm, and a precise temperature regulation strategy is adopted. S5: Generates a PWM signal based on the control output, controls the heating power of heating element 2 through the switching of MOS, and converts the control command into actual heating action, which directly affects the temperature change of the system; S6: Repeat steps S1 to S5 to form a closed-loop control until the temperature of constant temperature chamber 1 stabilizes within the target temperature range, ensuring continuous monitoring and adjustment of the system to maintain a long-term stable temperature control effect.

[0057] Through the above control method, this embodiment can achieve a temperature fluctuation of less than ±0.02℃ in the constant temperature chamber 1, thereby ensuring that the temperature fluctuation of the key component 6 under constant temperature protection is less than ±0.02℃. This high-precision temperature control can effectively eliminate the influence of temperature drift on the high-precision measurement system, significantly improving measurement accuracy and system stability.

[0058] It should be noted that this invention uses conventional metal materials, thermally conductive silicone pads, and thermal insulation materials. Through a simple and effective physical structure design, it achieves the goal of multi-point synchronous constant temperature control, which previously required complex electronic control systems. This solution avoids expensive custom components and complex assembly processes, offering extremely high cost-effectiveness and market competitiveness.

[0059] This invention, through the synergistic effect of a high thermal capacity platform, low thermal resistance coupling, and high thermal resistance isolation, can simultaneously provide a highly uniform temperature environment for multiple components and effectively suppress temperature drift caused by fluctuations in the power consumption of the components themselves and changes in the external environment. It integrates heating, conduction, coupling, and isolation into a compact module, realizing the transformation from multi-point temperature control to planar temperature control, and greatly simplifying the system structure of multi-point constant temperature.

[0060] The commonly used PWM direct drive heating method generates electromagnetic noise, which interferes with nearby sensitive circuits. This invention also solves the EMI problem of the traditional PWM direct drive method by using a preferred switching DC-DC converter circuit to provide smooth DC power to the heating film, thereby improving the overall reliability of the system.

[0061] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A thermostatic control system for a weighing apparatus, characterized by: The system comprises an oven, a heating element, a temperature sensor, a high-thermal-conductivity connecting material, a thermal insulation material, and a temperature control board. The bottom end of the heating element is provided with a foam, and the top end of the heating element is tightly arranged on the bottom surface of the oven.

2. A thermostatic control system for a weighing apparatus according to claim 1, wherein: The heating element comprises a heating film or a heating film and a semiconductor refrigeration sheet.

3. A thermostatic control system for a load cell according to claim 1, wherein: The temperature sensor is a PT1000 sensor or a PTC sensor.

4. A thermostatic control system for a load cell according to claim 1, wherein: The temperature control board comprises a temperature sampling circuit, a microcontroller, and a power driving circuit connected in sequence. The temperature sampling circuit samples and converts the output signal of the temperature sensor.

5. A thermostatic control system for a load cell according to claim 4, wherein, The microcontroller processes the temperature sampling data and executes a control algorithm to control the power driving circuit according to the temperature sampling data.

6. A thermostatic control system for a load cell according to claim 4, wherein, The power driving circuit drives the heating element according to the control signal of the microcontroller.

7. A thermostatic control system for a load cell according to claim 1, wherein The power driving circuit adopts a PWM control mode to control the heating power of the heating element by adjusting the duty cycle of the PWM signal.

8. A thermostatic control system for a load cell according to claim 1, wherein The microcontroller adopts a PI control algorithm to optimize the stability and rapidity of temperature control by adjusting the proportional gain parameter and the integral gain parameter.

9. A temperature control method for a thermostatic control system of a weighing apparatus according to any one of claims 1 to 8, characterized by, The oven is made of an aluminum plate, and the high-thermal-conductivity connecting material is thermal conductive silicone or thermal conductive silica gel. The temperature control precision of the system is ±0.02℃, and the temperature fluctuation range of the oven is ±0.02℃. The system comprises the following steps: S1: Real-time detection of the temperature of the oven by a temperature sensor; S2: Transmission of the detected temperature signal to a temperature control board for processing; S3: Comparison of the detected temperature with a set target temperature by the temperature control board to calculate a temperature deviation; S4: Calculation of the required control output based on the temperature deviation using a PI control algorithm; 10. The temperature control method according to claim 9, wherein S5: Generation of a PWM signal according to the control output to control the heating power of the heating element by the temperature control board; S6: Repeating steps S1 to S5 to form a closed-loop control until the temperature of the oven is stabilized within the target temperature range. In step S4, the PI control algorithm simplifies the temperature control system to a first-order system for processing, and adjusts the proportional gain parameter and the integral gain parameter to make the stability and response speed of the temperature controller meet the use requirements.

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