Closed-loop control temperature compensation device and method

Abstract

The invention relates to a closed-loop control temperature compensation device and method for a Stirling cryocooler drive controller. The temperature compensation device comprises a Stirling cryocooler, an upper computer and a monitor, the Stirling cryocooler is integrally arranged in an incubator during deployment, and the upper computer and the monitor are arranged outside the incubator. According to the temperature compensation method, the actual differential voltage fed back by a temperature sensor in the refrigeration assembly serves as the reference, the target voltage of closed-loop control serves as a temperature compensation object, and closed-loop temperature compensation calibration is achieved. The temperature excursion characteristic of the whole Stirling cryocooler is comprehensively considered, the temperature excursion characteristics of all circuits of the driving controller are covered, and the temperature excursion influence of the direct current motor and the refrigeration assembly is further included; compared with a traditional scheme of only calibrating the temperature excursion characteristic of the local circuit of the controller, the temperature compensation effect of the method is more in line with the actual working condition. Actual measurement shows that the temperature control accuracy of the three-temperature temperature of the Stirling cryocooler after temperature compensation is better than that of the Stirling cryocooler, and the temperature control accuracy is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of Stirling refrigerator technology, and specifically to a closed-loop control temperature compensation device and method for a Stirling refrigerator drive controller. Background Technology

[0002] Stirling cryogenic coolers are the most commonly used devices for providing a low-temperature operating environment for infrared detectors. They mainly consist of a drive controller, a Stirling brushless DC motor, and cooling components. The drive controller is the core component of the Stirling cryogenic cooler, its function being to precisely control the temperature of the cooler, thereby providing a precise and stable low-temperature operating environment for the infrared detector chip. In short, the performance of the drive controller directly determines the imaging quality of the infrared detection components.

[0003] The Stirling refrigerator drive controller mainly consists of a temperature acquisition circuit, a microcontroller unit, a pre-drive circuit, and an inverter circuit. These components work together to achieve precise and stable closed-loop control of the refrigeration temperature. Specifically, the temperature acquisition circuit collects the cold-end temperature of the refrigeration components in real time and feeds it back to the microcontroller unit. The microcontroller unit communicates with the host computer via a serial port to set control parameters and transmit data. Based on the real-time cold-end temperature, it uses a set control algorithm to generate and output a PWM wave with a specific duty cycle in real time, thereby controlling the pre-drive circuit. The pre-drive circuit uses the PWM wave provided by the microcontroller unit to control the switching state of the switches in the inverter circuit, thus controlling the speed and cold-end temperature of the brushless DC motor in the Stirling refrigerator, achieving precise and stable closed-loop control of the refrigeration temperature.

[0004] Stirling refrigerators typically operate over a wide temperature range, commonly -45°C to +105°C, and in some scenarios, even wider. Given a fixed target temperature for the refrigerator, if the drive controller lacks temperature compensation, the final cold-end temperature converged by the closed-loop control will vary under different ambient temperatures. This causes fluctuations in the operating environment temperature of the infrared detector, affecting its imaging quality. Several factors contribute to this cold-end temperature fluctuation, including: the deviation between the output of the temperature acquisition circuit in the drive controller and the actual cold-end temperature, changes in ambient temperature, the driving capability of the inverter circuit in the drive controller, the load-carrying capacity of the brushless DC motor in the Stirling refrigerator, and the heat exchange efficiency between the cooling components and the external environment. Therefore, to ensure the cold-end temperature of the cooling components remains constant under controlled conditions, unaffected by changes in ambient temperature, temperature compensation must be designed and implemented in the drive controller.

[0005] Traditional temperature compensation methods typically compensate based solely on the temperature drift characteristics of a single core component in the circuit. This single-dimensional approach is clearly insufficient for precise temperature control, resulting in unsatisfactory compensation effects. Currently, some literature offers improved solutions. For example, Chinese patent document CN 112462740A discloses a temperature compensation calibration method for a Stirling refrigerator controller. This method acquires the signal from a precision reference voltage source placed outside the temperature chamber and compensates to ensure that the output of the temperature acquisition circuit inside the chamber matches the acquired reference voltage. Chinese patent document CN 114034919A discloses a voltage acquisition device based on a microcontroller and its temperature compensation method. This method employs an interpolation temperature compensation algorithm, but its application relies on a linear relationship between the temperature measurement error of the temperature acquisition circuit and the ambient temperature. However, in actual operating conditions, this ideal linear relationship is often difficult to achieve, leading to limited operability of the compensation method. Furthermore, both of these patent documents share a common drawback: both only place the drive controller separately inside the temperature chamber for temperature compensation, placing the drive controller in an open-loop state. However, this open-loop state is completely different from the actual working state where the entire refrigeration unit is placed in the same environment and is under closed-loop control. Therefore, the temperature compensation result obtained in the open-loop state of the controller may not be compatible with the closed-loop state, which will not only greatly reduce the effect of the above temperature compensation, but may even lead to the opposite temperature control error due to the mismatch of operating conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a closed-loop control temperature compensation device and method for a Stirling refrigerator drive controller.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect of the present invention, a closed-loop control temperature compensation device is disclosed, the device comprising a Stirling refrigerator, a host computer, and a monitoring instrument; the Stirling refrigerator comprises a drive controller, a Stirling DC brushless motor, and a refrigeration component; the Stirling refrigerator is placed entirely inside a temperature chamber, while the host computer and the monitoring instrument are both located outside the temperature chamber.

[0008] As a further improvement to the above technical solution, the drive controller includes a temperature acquisition circuit, a microcontroller unit, an ambient temperature sensor, a pre-drive circuit, and an inverter circuit.

[0009] The input terminal of the microcontroller is connected to the output terminal of the temperature acquisition circuit and the output terminal of the ambient temperature sensor, respectively. The output terminal of the microcontroller is connected to the input terminal of the pre-drive circuit. The output terminal of the pre-drive circuit is connected to the input terminal of the inverter circuit. The output terminal of the inverter circuit is connected to the input terminal of the Stirling brushless DC motor.

[0010] The temperature acquisition circuit acquires the differential voltage fed back by the temperature sensor in the refrigeration component and transmits it to the microcontroller unit. After receiving the differential voltage, the microcontroller unit compares it with the preset temperature closed-loop control differential voltage target design value, calculates the voltage error and voltage error change rate, and then calculates the voltage error and voltage error change rate through the closed-loop control algorithm to generate and output a PWM wave with an adapted duty cycle. After being amplified by the pre-drive circuit, the PWM wave controls the on / off state of the power switch in the inverter circuit.

[0011] As a further improvement to the above technical solution, the ambient temperature sensor is used to collect the ambient temperature of the drive controller in real time.

[0012] As a further improvement to the above technical solution, the host computer is connected to the serial communication interface of the drive controller via an RS485 serial port to realize the transmission of control parameters and data feedback.

[0013] As a further improvement to the above technical solution, the monitoring instrument is connected to the positive and negative output terminals of the temperature sensor in the refrigeration component via a differential signal cable, for real-time acquisition and feedback of differential voltage signals.

[0014] In a second aspect of the present invention, a temperature compensation method for the closed-loop control temperature compensation device is disclosed, the method comprising the following steps: S1. Device setup and operational deployment: The closed-loop control temperature compensation device is set up, and the Stirling refrigerator is placed inside the temperature chamber, while the host computer and monitoring instrument are placed outside the temperature chamber.

[0015] S2. System initialization and parameter configuration: The drive controller and the temperature chamber are powered on and initialized. The initial temperature of the temperature chamber is adjusted to the minimum operating ambient temperature of the Stirling refrigerator, and the target value of the differential voltage corresponding to the cold end temperature of the refrigerator and the initial temperature compensation target value of the closed loop control are preset.

[0016] S3. Start-up and operation of closed-loop control of the refrigeration unit: Start the Stirling refrigeration unit to enter the closed-loop control working mode, and perform closed-loop control of the cold end temperature of the refrigeration unit based on the differential voltage feedback parameter.

[0017] S4. Temperature Maintenance in the Warm Chamber: Once the internal temperature of the warm chamber reaches the currently set temperature, the warm chamber will be controlled to enter a constant temperature state and maintain the temperature for a preset time.

[0018] S5. Determination of the convergence stability of the closed-loop control of the refrigeration unit: After the temperature chamber completes the constant temperature maintenance, the closed-loop temperature control system of the Stirling refrigeration unit is judged to have converged based on the feedback parameter of the differential voltage at the cold end of the refrigeration component.

[0019] S6. Temperature compensation target value adjustment: Obtain the actual value of the differential voltage at the cold end of the refrigeration unit, and determine whether to adjust the temperature compensation target value based on the deviation between the actual value of the differential voltage and the target value of the differential voltage.

[0020] S7. Target Temperature Update and Full Temperature Range Coverage Determination: Update the next target temperature of the temperature chamber and determine whether the current target temperature of the temperature chamber has covered the full operating temperature range of the Stirling refrigeration unit.

[0021] As a further improvement to the above technical solution, step S3 specifically includes the following steps: S31, the temperature acquisition circuit of the drive controller acquires the actual value of the differential voltage output by the temperature sensor at the cold end of the refrigeration component in real time at a fixed sampling period. V D,T This voltage corresponds one-to-one with the real-time temperature of the cold end.

[0022] S32, the microcontroller unit will collect the actual value of the differential voltage. V D,T Compared with the preset differential voltage target value V By comparing with zero, the differential voltage error was calculated. e ( t and error change rate ec ( t ). S33, the microcontroller unit uses a closed-loop control algorithm to control the differential voltage error. e ( t and error change rate ec ( t The system performs calculations to generate and output a PWM wave with an appropriate duty cycle. After being amplified by the pre-drive circuit, the PWM wave controls the on / off state of the power switch in the inverter circuit, thereby adjusting the power supply duty cycle of the Stirling brushless DC motor to regulate the motor speed. Finally, the cooling capacity of the cooling component is adjusted by the speed change, thus achieving closed-loop control of the cold end temperature of the cooling component.

[0023] As a further improvement to the above technical solution, step S5 specifically includes the following steps: S51. The actual value of the differential voltage at the cold end of the refrigeration component is collected in real time by the monitoring instrument. V D,T If the actual value of the differential voltage V D,T If the temperature fluctuates within a preset error range and the duration of this stable fluctuation is longer than a preset duration, then the differential voltage stability condition is met, and the closed-loop temperature control system is determined to have converged and stabilized.

[0024] S52. The cold end temperature of the refrigerator has reached a stable state, and the subsequent temperature compensation calibration process begins.

[0025] As a further improvement to the above technical solution, step S6 specifically includes the following steps: S61. After the closed-loop control of the refrigeration unit has converged and stabilized, read the actual value of the differential voltage displayed on the monitor, which is fed back by the temperature sensor in the refrigeration unit. V D,T .

[0026] S62. Use formula (1) to determine the actual value of the differential voltage at the cold end of the refrigeration component. V D,T With the target value of differential voltage V Is a deviation of 0 within the allowable error range? Within the range: (1).

[0027] S63. If the differential voltage error is within the allowable error range, then the current closed-loop control temperature compensation target value is updated using formula (2). D now The real-time temperature collected by the ambient temperature sensor in the drive controller T C Compared with the updated closed-loop control temperature compensation target value D now Synchronously store the data to the microcontroller unit, then proceed to step S7: (2); in, The closed-loop control temperature compensation target value is calibrated based on the actual value of the differential voltage fed back from the current operating environment temperature and the cooling component.

[0028] S64. If the differential voltage error is not within the allowable error range, then use formula (3) to calculate the new closed-loop control temperature compensation target value. The target temperature compensation value for closed-loop control is obtained through the host computer. After downloading to the microcontroller unit of the drive controller and updating the closed-loop control temperature compensation target value, return to step S5 to re-perform the closed-loop control convergence stability judgment until the differential voltage error meets the requirements: (3).

[0029] As a further improvement to the above technical solution, step S7 specifically includes the following steps: S71. Calculate and update the next target temperature of the chamber using formula (4): (4); in, T now This is the current temperature of the incubator. T next The next target temperature for the incubator. T This is the temperature scan step for the incubator.

[0030] S72. Based on the updated target temperature of the incubator, use formula (5) to determine whether it exceeds the upper limit of the operating temperature range of the refrigeration unit: (5); in, This represents the upper limit of the operating temperature range of the refrigeration unit.

[0031] S73. If formula (5) is true, then it is determined that the temperature of the incubator has covered the temperature range from... T min arrive T max The entire operating temperature range is reached, and the entire temperature compensation process is completed; if formula (5) does not hold, then the target temperature of the chamber is set to [the specified value]. T next Then return to step S5.

[0032] S74, when the temperature of the incubator T Complete from T min arrive T max After the full temperature range scan, the entire temperature compensation process is completed. The microcontroller unit generates and stores a two-dimensional data list in which the controller ambient temperature and the closed-loop control temperature compensation target value are one-to-one. When the Stirling refrigerator is working normally, the microcontroller unit retrieves the closed-loop control temperature compensation target value corresponding to the ambient temperature from the list in real time. If the controller's real-time ambient temperature is not completely consistent with the ambient temperature in the list, the closed-loop control temperature compensation target value at the current ambient temperature is calculated using the interpolation method shown in Equation (6). : (6); in, The current ambient temperature is the temperature sensed by the sensor. , They are respectively with The two closest calibrated ambient temperature values; , They are respectively , The corresponding closed-loop control temperature compensation target value.

[0033] Compared with the prior art, the advantages of the present invention are: (1) This invention relates to a closed-loop control temperature compensation device and method for a Stirling refrigerator drive controller. The temperature compensation device includes a Stirling refrigerator, a host computer, and a monitoring instrument. During deployment, the entire Stirling refrigerator is placed inside a temperature chamber, while the host computer and monitoring instrument are located outside the temperature chamber. The host computer is used to set various operating parameters of the Stirling refrigerator, and the monitoring instrument is used to monitor the differential voltage value output by the temperature sensor in the Stirling refrigeration component in real time. The temperature compensation method uses the actual differential voltage fed back by the temperature sensor in the refrigeration component as a reference and the target voltage of the closed-loop control as the temperature compensation object to achieve closed-loop temperature compensation calibration. The specific process is as follows: at the lowest operating temperature of the Stirling refrigerator... T min Up to the maximum operating temperature T max Within the range, with temperature scan step Δ T The temperature of the chamber is scanned across the entire temperature range. After each step of temperature compensation calibration, the corresponding temperature compensation result is saved to the microcontroller unit, ultimately forming a two-dimensional temperature compensation data list with a one-to-one correspondence between ambient temperature and target temperature compensation value. When the Stirling refrigerator is operating normally, the microcontroller unit can directly call the temperature compensation parameters matching the current ambient temperature from this list. If the current ambient temperature is not included in the list, the appropriate temperature compensation parameters can be calculated using interpolation. This temperature compensation method does not rely on assumptions such as the temperature drift characteristics of the devices and is characterized by its simplicity, intuitiveness, accuracy, reliability, and versatility.

[0034] (2) This invention comprehensively considers the temperature drift characteristics of the entire Stirling refrigerator, covering not only the temperature drift characteristics of all circuits in the drive controller itself, but also the temperature drift effects of the DC motor and refrigeration components. Compared with the traditional solution that only calibrates the temperature drift characteristics of local circuits in the controller, the temperature compensation effect of this invention is more in line with actual working conditions. Actual measurements show that the three-temperature control accuracy of the temperature-compensated Stirling refrigerator is better than... This invention significantly improves temperature control accuracy. It uses the actual differential voltage fed back by the temperature sensor in the refrigeration component as a reference and the closed-loop control target voltage as the compensation object for temperature compensation calibration. It does not rely on assumptions such as the linearity of temperature drift in the devices, and the calibration logic is simple, intuitive, and accurate, effectively avoiding compensation errors caused by discrepancies between assumptions and actual operating conditions. The temperature compensation method described in this invention is simple, without any assumptions, and does not require assuming that the temperature drift characteristics of certain devices are linear or piecewise linear, making it highly universal. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the closed-loop control temperature compensation device for the Stirling refrigerator drive controller in this invention. Figure 2 This is a flowchart of the closed-loop control temperature compensation method for the Stirling refrigerator drive controller in this invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings: This invention aims to address three key problems in existing technologies: first, the convergence temperature of the Stirling refrigerator's closed-loop control is prone to fluctuations with changes in ambient temperature, thus affecting the imaging quality of the infrared imaging system; second, traditional temperature compensation schemes suffer from poor accuracy; and third, traditional temperature compensation schemes also face the practical problem of poor operability. By overcoming these three key problems, this invention provides a superior temperature compensation solution for high-end cooled infrared imaging systems.

[0037] In a first aspect of the invention, a closed-loop control temperature compensation device for a Stirling refrigerator drive controller is disclosed, such as... Figure 1 As shown, the device includes a Stirling refrigerator, a host computer, and a monitoring instrument; the Stirling refrigerator includes a drive controller, a Stirling DC brushless motor, and refrigeration components. The Stirling refrigerator is placed inside the temperature chamber, while the host computer and monitoring instrument are located outside the temperature chamber.

[0038] like Figure 1 As shown, the drive controller includes a temperature acquisition circuit, a microcontroller unit, an ambient temperature sensor, a pre-drive circuit, and an inverter circuit. The input terminal of the microcontroller unit is connected to the output terminal of the temperature acquisition circuit and the output terminal of the ambient temperature sensor, respectively. The output terminal of the microcontroller unit is connected to the input terminal of the pre-drive circuit. The output terminal of the pre-drive circuit is connected to the input terminal of the inverter circuit. The output terminal of the inverter circuit is connected to the input terminal of the Stirling brushless DC motor. The host computer is connected to the serial communication interface of the drive controller via an RS485 serial port. The monitoring instrument is connected to the positive and negative output terminals of the temperature sensor in the refrigeration component via a differential signal cable to acquire differential voltage signals in real time. The differential signal cable adopts a shielded design to reduce electromagnetic interference.

[0039] Specifically, the temperature acquisition circuit acquires the differential voltage fed back by the temperature sensor in the refrigeration component and transmits it to the microcontroller unit. In this embodiment, a temperature-sensing diode is used as the temperature sensor. Based on the physical characteristics of the diode, when the forward bias current is constant, the forward conduction voltage drop of the temperature-sensing diode has a first-order linear relationship with the absolute temperature, that is, a temperature corresponds to a unique voltage value, and vice versa. In other words, the differential voltage fed back by the temperature sensor in the refrigeration component has a one-to-one correspondence with the real-time temperature of the refrigeration component.

[0040] Furthermore, after receiving the differential voltage, the microcontroller unit compares it with the preset target design value of the differential voltage for temperature closed-loop control, calculates parameters such as voltage error and voltage error change rate, and then calculates these parameters through the closed-loop control algorithm to generate and output a PWM wave with an appropriate duty cycle. After being amplified by the pre-drive circuit, the PWM wave controls the on / off state of the power switching transistors in the inverter circuit, ultimately achieving precise and stable control of the speed of the Stirling brushless DC motor and the temperature of the cooling components.

[0041] Furthermore, the ambient temperature sensor is used to collect the ambient temperature of the drive controller in real time, providing accurate ambient temperature data for temperature compensation operations in closed-loop control.

[0042] Furthermore, the host computer establishes a connection with the drive controller via serial communication to complete the setting of various parameters of the Stirling refrigerator, including the target design value of the differential voltage corresponding to the target temperature, closed-loop control parameters, etc.

[0043] Furthermore, the monitoring instrument is connected to the positive and negative output terminals of the temperature sensor in the refrigeration component via a differential signal cable, which is used to monitor the differential voltage value fed back by the temperature sensor in the refrigeration component in real time, so that the staff can grasp the temperature-related data of the refrigeration component in real time and provide a reference for the verification of compensation effect and process control.

[0044] Furthermore, the pre-drive circuit synchronously receives two signals: one is the position feedback information output from the Stirling brushless DC motor, and the other is the PWM signal generated by the microcontroller unit. The PWM signal, amplified by the pre-drive circuit, provides driving capability to the inverter circuit, controlling the on / off state of the six power MOSFETs in the inverter circuit. Combined with the position feedback information from the Stirling brushless DC motor, the real-time position of the motor rotor is determined, thereby identifying the specific combination of MOSFETs that are active at a given time.

[0045] In a second aspect of the present invention, a closed-loop control temperature compensation method for a Stirling refrigerator drive controller is disclosed, the method comprising the following steps: S1. Device setup and operational deployment: The closed-loop control temperature compensation device is set up, and the Stirling refrigerator is placed inside the temperature chamber, while the host computer and monitoring instrument are placed outside the temperature chamber.

[0046] During setup, it is essential to ensure correct connections and proper functioning of the drive controller, Stirling DC brushless motor, refrigeration components, host computer, and monitoring instrument to guarantee the smooth operation of the subsequent temperature compensation process. The entire Stirling refrigerator is placed inside the temperature chamber to simulate different ambient temperature scenarios that may be encountered in actual operation. Simultaneously, the host computer and monitoring instrument are placed outside the temperature chamber to avoid interference from temperature fluctuations within the chamber. The host computer is electrically connected to the Stirling refrigerator controller inside the chamber via cables to ensure it can transmit parameter setting commands. The monitoring instrument is electrically connected to the temperature sensors of the Stirling refrigerator's refrigeration components inside the chamber via cables to receive differential voltage signals corresponding to its temperature in real time.

[0047] This invention, by placing the entire Stirling refrigerator in a temperature chamber, directly compensates for the temperature drift characteristics of the entire unit, rather than just the temperature drift characteristics of local circuits, thereby improving the accuracy of temperature compensation. Actual test results show that the temperature control accuracy of the temperature-compensated Stirling refrigerator is better than... .

[0048] S2. System Initialization and Parameter Configuration: Power on the drive controller and the temperature chamber to initialize, and adjust the initial temperature of the temperature chamber to the minimum operating ambient temperature required by the Stirling refrigerator. T min And preset the target value of the differential voltage corresponding to the cold end temperature of the refrigeration unit. V 0 and the initial temperature compensation target value of closed-loop control D 0.

[0049] By setting the initial temperature of the incubator to the minimum operating ambient temperature required by the Stirling refrigerator. T min This ensures that the entire operating temperature range is gradually covered, starting from low-temperature conditions. In this embodiment, the specific parameters are set as follows: T min =-45℃, V 0 = 1.056V D 0 = 1778650.

[0050] S3. Start-up and operation of closed-loop control of the refrigeration unit: Start the Stirling refrigeration unit to enter the closed-loop control working mode, and perform closed-loop control of the cold end temperature of the refrigeration unit based on the differential voltage feedback parameter.

[0051] Step S3 specifically includes the following steps: S31, the temperature acquisition circuit of the drive controller acquires the actual value of the differential voltage output by the temperature sensor at the cold end of the refrigeration component in real time at a fixed sampling period. V D,T This voltage corresponds one-to-one with the real-time temperature of the cold end.

[0052] S32, the microcontroller unit will collect the actual value of the differential voltage. V D,T Compared with the preset differential voltage target value V By comparing with 0, the differential voltage error is calculated. e ( t and error change rate ec ( t ). e ( t )for V 0 and V D,T The difference, positive / negative, corresponds to the cold junction temperature being lower / higher than the target temperature, respectively, reflecting the direction and magnitude of the error; differential voltage error change rate. ec ( t () represents the change in error per unit time, reflecting the trend of temperature error.

[0053] S33. The microcontroller unit uses a closed-loop control algorithm (such as an incremental PID algorithm) to control the differential voltage error. e ( t and error change rate ec ( t The system performs calculations to generate and output a PWM wave with an appropriate duty cycle. After being amplified by the pre-drive circuit, the PWM wave controls the on / off state of the power switch in the inverter circuit, thereby adjusting the power supply duty cycle of the Stirling brushless DC motor to regulate the motor speed. Finally, the cooling capacity of the cooling component is adjusted by the speed change, thus achieving closed-loop control of the cold end temperature of the cooling component.

[0054] After completing system initialization and parameter configuration, the Stirling refrigerator is started, putting it into closed-loop control mode. At this time, the drive controller will operate according to the preset differential voltage target value. V 0 and closed-loop control temperature compensation target value D 0. Triggering Closed-Loop Control: The temperature acquisition circuit collects the differential voltage at the cold end of the refrigeration component in real time and feeds it back to the microcontroller unit. The microcontroller unit calculates the voltage error through a closed-loop control algorithm, and then outputs a PWM wave with a corresponding duty cycle. This sequentially controls the pre-drive circuit and the inverter circuit, ultimately adjusting the speed of the Stirling brushless DC motor to regulate the cold end temperature, forming a complete closed loop of acquisition-calculation-control-feedback. In this embodiment, the closed-loop control algorithm is a fuzzy adaptive incremental PID closed-loop control algorithm. This algorithm calculates parameters such as differential voltage error and voltage error change rate, generating and outputting a PWM wave with a suitable duty cycle.

[0055] S4. Temperature Maintenance in the Incubator: Once the internal temperature of the incubator reaches the currently set temperature, the incubator will enter a constant temperature state and maintain the temperature for a preset duration Δ. t .

[0056] In this embodiment, the set continuous heat preservation time Δ t The time is 0.5 hours. This value ensures that the overall temperature of the unit is completely consistent with the ambient temperature of the chamber, while avoiding excessively long holding times that could reduce temperature compensation efficiency. The purpose of this step is to allow the entire Stirling refrigerator (including the drive controller, motor, and refrigeration components) to fully adapt to the current ambient temperature, ensuring that the temperature drift characteristics of each component are stably displayed, and providing a stable temperature environment for subsequent closed-loop control temperature compensation calibration.

[0057] S5. Determination of the convergence stability of the closed-loop control of the refrigeration unit: After the temperature chamber completes the constant temperature maintenance, the closed-loop temperature control system of the Stirling refrigeration unit is judged to have converged based on the feedback parameter of the differential voltage at the cold end of the refrigeration component.

[0058] Step S5 specifically includes the following steps: S51. The actual value of the differential voltage at the cold end of the refrigeration component is collected in real time by the monitoring instrument. V D,T If the actual value of the differential voltage V D,T If the voltage fluctuates continuously within a preset error range, such as 20μV, and the duration of this stable fluctuation is longer than the preset duration, then the stability condition of the differential voltage is met, and the closed-loop temperature control system is determined to have converged and stabilized. S52. When the cold end temperature of the refrigeration unit reaches a stable state, the subsequent temperature compensation calibration process can begin, providing a stable reference condition for temperature compensation calibration.

[0059] S6. Temperature compensation target value adjustment: Obtain the actual value of the differential voltage at the cold end of the refrigeration unit, and determine whether to adjust the temperature compensation target value based on the deviation between the actual value of the differential voltage and the target value of the differential voltage.

[0060] Step S6 specifically includes the following steps: S61. After the closed-loop control of the refrigeration unit has converged and stabilized, read the actual value of the differential voltage currently displayed on the monitor, which is transmitted back from the temperature sensor in the refrigeration unit. V D,T .

[0061] Step S61 is used to obtain the actual value of the differential voltage at the cold end of the refrigeration component at the current ambient temperature. V D,T The actual value of the differential voltage V D,T It corresponds one-to-one with the cold junction temperature of the refrigeration components, providing direct measured data for subsequent determination of whether compensation is needed and accurate calculation of the compensation amount, ensuring that the entire compensation calibration process is always based on the real cold junction temperature feedback signal, and guaranteeing the accuracy of the temperature compensation results.

[0062] S62. Use formula (1) to determine the actual value of the differential voltage at the cold end of the refrigeration component. V D,T With the target value of differential voltage V Is a deviation of 0 within the allowable error range? (1); In this embodiment, V The value of 0 is 1.056V. Values 45μV, of which, V The value of 0 was determined through previous experiments. The selected value is compatible with normal sensor measurement errors while ensuring that the cold junction temperature error does not exceed the temperature control accuracy requirements.

[0063] S63. If the differential voltage error is within the allowable error range, then the current closed-loop control temperature compensation target value is updated using formula (2). D now The real-time temperature collected by the ambient temperature sensor in the drive controller T C Compared with the updated closed-loop control temperature compensation target value D now Synchronously store the data to the microcontroller unit, then proceed to step S7: (2); in, The closed-loop control temperature compensation target value is calibrated based on the actual value of the differential voltage fed back from the current operating environment temperature and the cooling component.

[0064] S64. If the differential voltage error is not within the allowable error range, then use formula (3) to calculate the new closed-loop control temperature compensation target value. The closed-loop control temperature compensation target value is then transmitted via a host computer. After downloading to the microcontroller unit of the drive controller and updating the closed-loop control temperature compensation target value, return to step S5 to re-perform the closed-loop control convergence stability judgment until the differential voltage error meets the requirements, ensuring that subsequent temperature compensation is based on the accurate control target.

[0065] (3).

[0066] S7. Target Temperature Update and Full Temperature Range Coverage Determination: Update the next target temperature of the temperature chamber and determine whether the current target temperature of the temperature chamber has covered the full operating temperature range of the Stirling refrigeration unit.

[0067] Step S7 specifically includes the following steps: S71. Calculate and update the next target temperature of the chamber using formula (4): (4); in, T now This is the current temperature of the incubator. T next The next target temperature for the incubator. T In this embodiment, the temperature scanning step of the incubator is described. The temperature is 5℃.

[0068] S72. Based on the updated target temperature of the incubator, use formula (5) to determine whether the current target temperature of the incubator exceeds the upper limit of the operating temperature range of the refrigeration unit: (5); in, This represents the upper limit of the operating temperature range of the refrigeration unit.

[0069] S73. If formula (5) is true, then it is determined that the temperature of the incubator has covered the temperature range from... T min arrive T max The entire working temperature range is reached, and the entire temperature compensation process is completed; if formula (5) is not valid, the target temperature of the chamber is set to the calculated new temperature, and the process returns to step S5.

[0070] In this embodiment, The value is 105℃.

[0071] S74, when the temperature of the incubator T Complete from T min arrive T max After a full-temperature-range scan, the entire temperature compensation process is completed, and a two-dimensional data list with a one-to-one correspondence between the controller's ambient temperature and the closed-loop control temperature compensation target value is generated and stored in the microcontroller unit. When the Stirling refrigerator is working normally, the microcontroller unit retrieves the closed-loop control temperature compensation target value corresponding to the ambient temperature from this list in real time. If the controller's real-time ambient temperature is not completely consistent with the ambient temperature in the list, the closed-loop control temperature compensation target value at the current ambient temperature is calculated using the interpolation method shown in equation (6). .

[0072] (6); in, The current ambient temperature is the temperature sensed by the sensor. , They are respectively with The two closest calibrated ambient temperature values; , They are respectively , The corresponding closed-loop control temperature compensation target value.

[0073] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A closed-loop temperature compensation device, comprising a Stirling refrigerator, a host computer, and a monitoring instrument; wherein the Stirling refrigerator comprises a drive controller, a Stirling brushless DC motor, and a refrigeration assembly; characterized in that, The Stirling refrigeration unit is placed inside the temperature chamber, while the host computer and monitoring instrument are located outside the temperature chamber.

2. The closed-loop control temperature compensation device according to claim 1, characterized in that, The drive controller includes a temperature acquisition circuit, a microcontroller unit, an ambient temperature sensor, a pre-drive circuit, and an inverter circuit. The input terminal of the microcontroller is connected to the output terminal of the temperature acquisition circuit and the output terminal of the ambient temperature sensor, respectively. The output terminal of the microcontroller is connected to the input terminal of the pre-drive circuit. The output terminal of the pre-drive circuit is connected to the input terminal of the inverter circuit. The output terminal of the inverter circuit is connected to the input terminal of the Stirling brushless DC motor. The temperature acquisition circuit acquires the differential voltage fed back by the temperature sensor in the refrigeration component and transmits it to the microcontroller unit. After receiving the differential voltage, the microcontroller unit compares it with the preset temperature closed-loop control differential voltage target design value, calculates the voltage error and voltage error change rate, and then calculates the voltage error and voltage error change rate through the closed-loop control algorithm to generate and output a PWM wave with an adapted duty cycle. After being amplified by the pre-drive circuit, the PWM wave controls the on / off state of the power switch in the inverter circuit.

3. The closed-loop control temperature compensation device according to claim 2, characterized in that, The ambient temperature sensor is used to collect the ambient temperature of the drive controller in real time.

4. The closed-loop control temperature compensation device according to claim 2, characterized in that, The host computer is connected to the serial communication interface of the drive controller via an RS485 serial port to realize the transmission of control parameters and data feedback.

5. The closed-loop control temperature compensation device according to claim 2, characterized in that, The monitoring instrument is connected to the positive and negative output terminals of the temperature sensor in the refrigeration assembly via a differential signal cable to collect differential voltage signals in real time.

6. A temperature compensation method for a closed-loop control temperature compensation device according to any one of claims 1 to 5, characterized in that, The method includes the following steps: S1. Device setup and operational deployment: The closed-loop control temperature compensation device is set up, and the Stirling refrigerator is placed inside the temperature chamber, while the host computer and monitoring instrument are placed outside the temperature chamber. S2. System initialization and parameter configuration: Power on the drive controller and the temperature chamber to initialize, adjust the initial temperature of the temperature chamber to the minimum operating ambient temperature of the Stirling refrigerator, and preset the target value of the differential voltage corresponding to the cold end temperature of the refrigerator and the initial temperature compensation target value of the closed loop control. S3. Start-up and operation of closed-loop control of the refrigeration unit: Start the Stirling refrigeration unit to enter the closed-loop control working mode, and perform closed-loop control of the cold end temperature of the refrigeration unit based on the differential voltage feedback parameter. S4. Temperature control in the incubator: Once the internal temperature of the incubator reaches the current set temperature, the incubator will enter a constant temperature state and maintain the temperature for a preset time. S5. Determination of the convergence stability of the closed-loop control of the refrigeration unit: After the temperature chamber completes the constant temperature maintenance, the closed-loop temperature control system of the Stirling refrigeration unit is judged to converge based on the feedback parameter of the differential voltage of the cold end of the refrigeration unit. S6. Temperature compensation target value adjustment: Obtain the actual value of the differential voltage at the cold end of the refrigeration unit, and determine whether to adjust the temperature compensation target value based on the deviation between the actual value of the differential voltage and the target value of the differential voltage. S7. Target Temperature Update and Full Temperature Range Coverage Determination: Update the next target temperature of the temperature chamber and determine whether the current target temperature of the temperature chamber has covered the full operating temperature range of the Stirling refrigeration unit.

7. The closed-loop control temperature compensation method according to claim 6, characterized in that, Step S3 specifically includes the following steps: S31, the temperature acquisition circuit of the drive controller acquires the actual value of the differential voltage output by the temperature sensor at the cold end of the refrigeration component in real time at a fixed sampling period. V D,T This voltage corresponds one-to-one with the real-time temperature of the cold end; S32, the microcontroller unit will collect the actual value of the differential voltage. V D,T Compared with the preset differential voltage target value V By comparing with zero, the differential voltage error was calculated. e ( t and error change rate ec ( t ); S33, the microcontroller unit uses a closed-loop control algorithm to control the differential voltage error. e ( t and error change rate ec ( t The system performs calculations to generate and output a PWM wave with an appropriate duty cycle. After being amplified by the pre-drive circuit, the PWM wave controls the on / off state of the power switch in the inverter circuit, thereby adjusting the power supply duty cycle of the Stirling brushless DC motor to regulate the motor speed. Finally, the cooling capacity of the cooling component is adjusted by the speed change, thus achieving closed-loop control of the cold end temperature of the cooling component.

8. The closed-loop control temperature compensation method according to claim 7, characterized in that, Step S5 specifically includes the following steps: S51. The actual value of the differential voltage at the cold end of the refrigeration component is collected in real time by the monitoring instrument. V D,T If the actual value of the differential voltage V D,T If the temperature fluctuates within the preset error range and the stable fluctuation state is maintained for a longer than the preset duration, then the differential voltage stability condition is met, and the closed-loop temperature control system is determined to have converged and stabilized. S52. The cold end temperature of the refrigerator has reached a stable state, and the subsequent temperature compensation calibration process begins.

9. The closed-loop control temperature compensation method according to claim 8, characterized in that, Step S6 specifically includes the following steps: S61. After the closed-loop control of the refrigeration unit has converged and stabilized, read the actual value of the differential voltage displayed on the monitor, which is fed back by the temperature sensor in the refrigeration unit. V D,T ; S62. Use formula (1) to determine the actual value of the differential voltage at the cold end of the refrigeration component. V D,T With the target value of differential voltage V Is a deviation of 0 within the allowable error range? Within the range: （1）； S63. If the differential voltage error is within the allowable error range, then the current closed-loop control temperature compensation target value is updated using formula (2). D now The real-time temperature collected by the ambient temperature sensor in the drive controller T C Compared with the updated closed-loop control temperature compensation target value D now Synchronously store the data to the microcontroller unit, then proceed to step S7: （2）； in, The closed-loop control temperature compensation target value is calibrated based on the actual value of the differential voltage fed back by the current operating environment temperature and the cooling component. S64. If the differential voltage error is not within the allowable error range, then use formula (3) to calculate the new closed-loop control temperature compensation target value. The target temperature compensation value for closed-loop control is obtained through the host computer. After downloading to the microcontroller unit of the drive controller and updating the closed-loop control temperature compensation target value, return to step S5 to re-perform the closed-loop control convergence stability judgment until the differential voltage error meets the requirements: （3）。 10. The closed-loop control temperature compensation method according to claim 9, characterized in that, Step S7 specifically includes the following steps: S71. Calculate and update the next target temperature of the chamber using formula (4): （4）； in, T now This is the current temperature of the incubator. T next The next target temperature for the incubator. T For the temperature scan step of the incubator; S72. Based on the updated target temperature of the incubator, use formula (5) to determine whether it exceeds the upper limit of the operating temperature range of the refrigeration unit: （5）； in, This represents the upper limit of the operating temperature range of the refrigeration unit; S73. If formula (5) is true, then it is determined that the temperature of the incubator has covered the temperature range from... T min arrive T max The entire operating temperature range is reached, and the entire temperature compensation process is completed; if formula (5) does not hold, then the target temperature of the chamber is set to [the specified value]. T next And return to step S5; S74, when the temperature of the incubator T Complete from T min arrive T max After the full temperature range scan, the entire temperature compensation process is completed. The microcontroller unit generates and stores a two-dimensional data list in which the controller ambient temperature and the closed-loop control temperature compensation target value are one-to-one. When the Stirling refrigerator is working normally, the microcontroller unit retrieves the closed-loop control temperature compensation target value corresponding to the ambient temperature from the list in real time. If the controller's real-time ambient temperature is not completely consistent with the ambient temperature in the list, the closed-loop control temperature compensation target value at the current ambient temperature is calculated using the interpolation method shown in Equation (6). : （6）； in, The current ambient temperature is the temperature sensed by the sensor. , They are respectively with The two closest calibrated ambient temperature values; , They are respectively , The corresponding closed-loop control temperature compensation target value.

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