Chromatographic column temperature control device for a chromatograph and its control method

Abstract

A chromatographic column temperature control device and its control method for a chromatograph belong to the technical field of chromatographic column temperature control of chromatographs; the technical problem to be solved is: to provide an improvement in the hardware structure of a chromatographic column temperature control device for a chromatograph and its control method; the technical solution adopted to solve this technical problem is: including a column box body, the column box body is a box body sealed on all sides, and a column box insulation layer is arranged inside the column box body; a first temperature measuring resistance sensor, a chromatographic column, a heating device, a second temperature measuring resistance sensor, a cooling motor, a blower motor and an electrical control box are arranged inside the column box body, a cooling port is arranged at the bottom of the column box body, and a hollowed-out heat sink is also arranged at the position of the cooling port; the chromatographic column is arranged in the middle of the column box body through a bracket, a first temperature measuring resistance sensor is separately arranged above the chromatographic column, and a heating device is arranged below the chromatographic column; the present invention is applied to a chromatograph.

Description

Technical Field

[0001] A chromatographic column temperature control device and its control method for a chromatograph according to the present invention belong to the technical field of chromatographic column temperature control of chromatographs. Background Art

[0002] Currently, gas chromatographs are used for qualitative and quantitative determination of volatile organic compound parameters, mainly applied in the field of on-line monitoring of volatile organic compounds in flue gas, atmosphere or water quality; the temperature control accuracy of the chromatograph will directly affect the effective separation of target substances in the chromatographic column, and is directly reflected in the peak shape and response time. During use, due to factors such as thermal inertia, hysteresis, thermal conductivity and external environment, various interferences will be generated on the chromatographic column temperature, resulting in poor separation of target substances, poor peak shape, appearance of other interfering impurity peaks, inability to perform integration calculation, or large calculation processing errors, and unable to accurately reflect the concentration of the measured component.

[0003] To solve the above technical problems, currently, mainly a high-power heating device is used to quickly heat the sealed column oven. This method will cause a long heating lag time and large thermal inertia of the chromatographic column, resulting in the chromatographic column fluctuating within a large temperature range for a long time. In addition, simply performing simple PID control based on the temperature detected by a thermal sensor cannot calculate and compensate for heating lag and loss. Summary of the Invention

[0004] In order to overcome the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide an improvement in the hardware structure of a chromatographic column temperature control device for a chromatograph and its control method.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a chromatographic column temperature control device for a chromatograph, including a column oven body, the column oven body is a box body sealed on all sides, and a column oven insulation layer is provided inside the column oven body;

[0006] A first temperature measuring resistance sensor, a chromatographic column, a heating device, a second temperature measuring resistance sensor, a heat dissipation motor, a blower motor and an electrical control box are arranged inside the column oven body. A heat dissipation port is provided at the bottom of the column oven body, and a hollowed-out heat dissipation fin is also provided at the position of the heat dissipation port;

[0007] The chromatographic column is arranged in the middle of the column oven body through a bracket. A first temperature measuring resistance sensor is arranged above the chromatographic column, and a heating device is arranged below the chromatographic column;

[0008] The heat dissipation motor is arranged at the heat dissipation port of the column oven body, and a second temperature measuring resistance sensor is also arranged inside the heat dissipation port of the column oven body;

[0009] The blower motor is arranged below the heating device;

[0010] Inside the chromatographic column, a resistance heating element is provided;

[0011] The electrical control box is fixed to the bottom surface of the column box by screws. Inside the electrical control box, a control circuit board is provided. The control circuit board integrates a microcontroller and peripheral circuits. The peripheral circuits include an AD / DA conversion module, an optoelectronic isolation module, a power operational amplifier module, and a motor drive module. The microcontroller is connected to the resistance heating element through the AD / DA conversion module, the optoelectronic isolation module, and the power operational amplifier module in sequence through wires. The signal output terminal of the microcontroller is connected to the blower motor and the cooling motor through the motor drive module;

[0012] The microcontroller is also connected to a data communication module and a data storage module;

[0013] The power input terminal of the microcontroller is connected to a power module;

[0014] The first temperature-measuring resistance sensor and the second temperature-measuring resistance sensor are connected to the signal input terminal of the microcontroller through wires.

[0015] The chips used in the power operational amplifier module are control chip U7, inverting amplifier U8, and inverting amplifier U9;

[0016] The circuit structure of the power operational amplifier module is as follows:

[0017] Pin 1 of control chip U7 and pin 12 of control chip U7 are connected to the signal output terminal of the resistance heating element;

[0018] Pins 2 to 6 of control chip U7 are connected to each other and then grounded;

[0019] Pin 7 of control chip U7 is connected to one end of capacitor C30 and then connected to the +5V power supply;

[0020] Pin 8 of control chip U7 is connected to the other end of capacitor C30 and then grounded;

[0021] Pin 9 of control chip U7 is connected to pin 13 of control chip U7 and then grounded;

[0022] Pin 14 of control chip U7 is connected to one end of resistor R19. The other end of resistor R19 is connected to pin 3 of inverting amplifier U9 after being connected to one end of resistor R20;

[0023] Pin 15 of control chip U7 is connected to one end of resistor R16. The other end of resistor R16 is connected to pin 4 of inverting amplifier U9 after being connected to one end of resistor R14. The other end of resistor R14 is connected to pin 1 of inverting amplifier U9 after being connected to one end of resistor R17;

[0024] The 16th pin of the control chip U7 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C22;

[0025] The 2nd pin of the inverting amplifier U9 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C29;

[0026] The 5th pin of the inverting amplifier U9 is connected to the +5V power supply after being connected in parallel with one end of the capacitor C26;

[0027] The other end of the resistor R17 is connected to one end of the resistor R18 and then connected to one end of the capacitor C19;

[0028] The other end of the resistor R18 is connected to one end of the capacitor C27 and then connected to the 3rd pin of the inverting amplifier U8;

[0029] The other end of the capacitor C19 is connected to one end of the resistor R13 and then connected to the 1st pin of the inverting amplifier U8;

[0030] The other end of the resistor R13 is connected to one end of the resistor R12 and then connected to the 4th pin of the inverting amplifier U8;

[0031] The 2nd pin of the inverting amplifier U8 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C28;

[0032] The 5th pin of the inverting amplifier U8 is connected to the +5V power supply after being connected in parallel with one end of the capacitor C23.

[0033] The models of the first temperature measurement resistance sensor and the second temperature measurement resistance sensor are PT100;

[0034] The model of the control chip used inside the microcontroller is STM32F103C8T6;

[0035] The model used inside the optoelectronic isolation module is PC817;

[0036] The model of the control chip U7 used in the power operational amplifier module is ADG733, and the models of the inverting amplifier U8 and the inverting amplifier U9 are AD8628;

[0037] The resistance heating body is specifically a 220W heating resistor controlled by a triac.

[0038] A method for controlling the temperature of a chromatographic column of a chromatograph, comprising the following steps:

[0039] Step 1: Start the chromatograph, and the microcontroller controls the temperature measurement resistance sensor to work, collect the current temperature data inside the column box in real time, and feed the collected data back to the microcontroller;

[0040] Step 2: The microcontroller analyzes and processes the temperature data, displays the result on the display screen, calculates the temperature difference and change rate of the temperature through a preset temperature threshold, calculates the compensated temperature data through an algorithm, and the temperature control mathematical model is:

[0041] ;

[0042] where: Td is the inertia time constant, Kd is the amplification coefficient, t is the lag time constant, and s is the complex variable;

[0043] The signal is converted and then controls the voltage across the resistance heating element through a thyristor;

[0044] Step 3: The microcontroller processes the temperature compensation data, converts it into corresponding heating drive frequencies and motor output pulse signals, and is used to control the cooling fan motor and the blower motor for corresponding temperature control;

[0045] Step 4: The controlled temperature is collected in real time by the temperature measuring resistance sensor, and the temperature data is fed back to the microcontroller. The microcontroller ensures that the current temperature is within the controlled temperature range to complete the processing and end the control.

[0046] The beneficial effects of the present invention compared with the prior art are as follows: The present invention realizes the rapid heating of the sealed column box through the 220W heating resistor controlled by a bidirectional thyristor and the blower motor arranged inside the heating device, and realizes the heat dissipation of the column box through the large-area hollowed-out heat sink and the cooling fan motor arranged on the column box body. Through the methods of blowing and heating and heat dissipation by the large-area hollowed-out heat sink, the heating lag of the chromatographic column is reduced, and the problem of thermal conductivity loss is solved. The present invention also suppresses the continuous action of thermal inertia by triggering the opening amplitude of the heat dissipation ventilation channel through thermal inertia, so as to realize the precise control of the temperature range of the chromatographic column. In addition, optimizing the control algorithm of the cooling frequency conversion can effectively reduce the temperature fluctuation during the temperature control of the chromatographic column, and the temperature control accuracy can reach ±0.1 °C, ensuring that components with different boiling points have appropriate retention in the chromatographic column, realizing uniform and symmetric chromatographic peak distribution, and making the integration operation accurate. Brief Description of the Drawings

[0047] The following further describes the present invention with reference to the drawings:

[0048] Figure 1 is the structural schematic diagram of the present invention;

[0049] Figure 2 is the circuit structural schematic diagram of the present invention;

[0050] Figure 3 is the circuit diagram of the microcontroller of the present invention;

[0051] Figure 4 is the circuit diagram of the power op-amp module of the present invention;

[0052] Figure 5 is the step flow chart of the temperature control method of the present invention;

[0053] In the figure: 1 is the column box body, 2 is the column box insulation layer, 3 is the first temperature measuring resistance sensor, 4 is the chromatographic column, 5 is the heating device, 6 is the second temperature measuring resistance sensor, 7 is the heat dissipation motor, 8 is the air blowing motor, 9 is the electrical control box, 10 is the resistance heating element, 11 is the microcontroller, 12 is the AD / DA conversion module, 13 is the optoelectronic isolation module, 14 is the power operation amplifier module, 15 is the motor drive module, 18 is the data communication module, 19 is the data storage module, 20 is the power supply module. Specific embodiments

[0054] As Figures 1 to 5 shown, a chromatographic column temperature control device of a chromatograph according to the present invention includes a column box body (1), the column box body (1) is a box body sealed on all sides, and a column box insulation layer (2) is arranged inside the column box body (1);

[0055] A first temperature measuring resistance sensor (3), a chromatographic column (4), a heating device (5), a second temperature measuring resistance sensor (6), a heat dissipation motor (7), an air blowing motor (8) and an electrical control box (9) are arranged inside the column box body (1), a heat dissipation port is arranged at the bottom of the column box body (1), and a hollowed-out heat dissipation fin is also arranged at the position of the heat dissipation port;

[0056] The chromatographic column (4) is arranged in the middle of the column box body (1) through a bracket, a first temperature measuring resistance sensor (3) is arranged above the chromatographic column (4), and a heating device (5) is arranged below the chromatographic column (4);

[0057] The heat dissipation motor (7) is arranged at the heat dissipation port of the column box body (1), and a second temperature measuring resistance sensor (6) is also arranged inside the heat dissipation port of the column box body (1);

[0058] The air blowing motor (8) is arranged below the heating device (5);

[0059] A resistance heating element (10) is arranged inside the chromatographic column (4);

[0060] The electrical control box (9) is fixed to the bottom surface of the column box body (1) by screws. A control circuit board is arranged inside the electrical control box (9), and a microcontroller (11) and a peripheral circuit are integrated on the control circuit board. The peripheral circuit includes an AD / DA conversion module (12), an optoelectronic isolation module (13), a power operational amplifier module (14), and a motor drive module (15). The microcontroller (11) is connected to a resistance heating element (10) through the AD / DA conversion module (12), the optoelectronic isolation module (13), and the power operational amplifier module (14) in sequence by wires. The signal output end of the microcontroller (11) is connected to a blast motor (8) and a cooling motor (7) through the motor drive module (15);

[0061] The microcontroller (11) is also connected to a data communication module (18) and a data storage module (19);

[0062] The power input end of the microcontroller (11) is connected to a power supply module (20);

[0063] The first temperature measuring resistance sensor (3) and the second temperature measuring resistance sensor (6) are connected to the signal input end of the microcontroller (11) through wires.

[0064] The chips used in the power operational amplifier module (14) are a control chip U7, an inverting amplifier U8, and an inverting amplifier U9;

[0065] The circuit structure of the power operational amplifier module (14) is as follows:

[0066] Pin 1 of the control chip U7 and pin 12 of the control chip U7 are connected to the signal output end of the resistance heating element (10);

[0067] Pins 2 to 6 of the control chip U7 are connected to each other and then grounded;

[0068] Pin 7 of the control chip U7 is connected to the +5V power supply after being connected in parallel with one end of a capacitor C30;

[0069] The other end of the capacitor C30 is connected to ground after being connected in parallel with pin 8 of the control chip U7;

[0070] Pin 9 of the control chip U7 is connected to pin 13 of the control chip U7 and then grounded;

[0071] Pin 14 of the control chip U7 is connected to one end of a resistor R19. The other end of the resistor R19 is connected to pin 3 of the inverting amplifier U9 after being connected in parallel with one end of a resistor R20;

[0072] The 15th pin of the control chip U7 is connected to one end of the resistor R16. The other end of the resistor R16 is connected to the 4th pin of the inverting amplifier U9 after being connected in parallel with one end of the resistor R14. The other end of the resistor R14 is connected to the 1st pin of the inverting amplifier U9 after being connected in parallel with one end of the resistor R17;

[0073] The 16th pin of the control chip U7 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C22;

[0074] The 2nd pin of the inverting amplifier U9 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C29;

[0075] The 5th pin of the inverting amplifier U9 is connected to the +5V power supply after being connected in parallel with one end of the capacitor C26;

[0076] The other end of the resistor R17 is connected to one end of the capacitor C19 after being connected in parallel with one end of the resistor R18;

[0077] The other end of the resistor R18 is connected to the 3rd pin of the inverting amplifier U8 after being connected in parallel with one end of the capacitor C27;

[0078] The other end of the capacitor C19 is connected to the 1st pin of the inverting amplifier U8 after being connected in parallel with one end of the resistor R13;

[0079] The other end of the resistor R13 is connected to the 4th pin of the inverting amplifier U8 after being connected in parallel with one end of the resistor R12;

[0080] The 2nd pin of the inverting amplifier U8 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C28;

[0081] The 5th pin of the inverting amplifier U8 is connected to the +5V power supply after being connected in parallel with one end of the capacitor C23.

[0082] The models of the first temperature measurement resistance sensor (3) and the second temperature measurement resistance sensor (6) are PT100;

[0083] The model of the control chip used inside the microcontroller (11) is STM32F103C8T6;

[0084] The model used inside the opto-isolation module (13) is PC817;

[0085] The model of the control chip U7 used in the power operational amplifier module (14) is ADG733, and the models of the inverting amplifier U8 and the inverting amplifier U9 are AD8628;

[0086] The resistance heating element (10) is specifically a 220W heating resistor controlled by a triac.

[0087] The present invention mainly improves the column box structure of the chromatograph, improves the heating and heat dissipation methods of the box body, and optimizes the temperature control algorithm, so as to solve the problem that the chromatographic column in the column box cannot reach the corresponding accuracy during the temperature control process, resulting in poor resolution and bad peak shape.

[0088] The present invention adopts the methods of blowing air for heating and designing a large-area hollowed-out heat sink to further reduce the problems of heating lag and heat conduction loss of the chromatographic column, and uses the method of triggering the opening amplitude of the heat dissipation ventilation channel by thermal inertia to suppress the continuous action of thermal inertia.

[0089] The present invention uses the integral saturation suppression separation method and the variable proportional coefficient algorithm to continuously track and adjust the heating dynamic process, compensate for the temperature fluctuations caused by thermal lag and heat loss, adds a continuous sampling trigger step to the control algorithm, and adaptively controls the output function to control the heat dissipation channel function to suppress the persistence of thermal inertia.

[0090] During specific use, the control object of the present invention is a sealed interval of about 0.01 cubic meters heated by a 220W heating resistor controlled by a bidirectional thyristor. The required control temperature range is 35 - 300 °C, and the temperature control accuracy in the heat preservation stage reaches ±0.1 °C;

[0091] When measuring the temperature, a high-precision platinum resistance sensor is selected, and the signal is converted and then the voltage across the heating resistor is controlled through the thyristor; the temperature control mathematical model is:

[0092] ;

[0093] Where: Td is the inertia time constant, Kd is the amplification coefficient, t is the lag time constant, and s is the complex variable.

[0094] When the present invention is in use, the corresponding application program is executed, which mainly consists of a main program, an interrupt service program, and related subprograms; the main program mainly initializes the system, realizes parameter input, and controls the driving frequency of the heating wire and the opening size of the heat dissipation channel in real time according to the temperature target and the actual value. The main program mainly consists of parts such as system initialization, data acquisition and processing, and data processing. System initialization includes steps such as setting the stack bottom, working register group, control quantity initialization, interrupt mode, sampling period, and pulse output initialization. Data acquisition and processing mainly include real-time acquisition of the temperature signal of the chromatographic column box, calculation of the difference between the actual temperature and the preset threshold and the temperature difference change rate, and finally filtering and suppressing separation of the temperature signal and calculating the output pulse for controlling the motor of the heat dissipation channel of the chromatographic column box, and compensating and optimizing the heating process according to the calculated proportional coefficient.

[0095] Further, the control system of the present invention takes the STM32F103C8T6 single-chip microcomputer as the core, and includes modules such as temperature signal conversion, amplification, high-power operational amplifier, A / D and D / A converters, optoelectronic isolation, drive circuit, communication circuit, memory, etc.;

[0096] When in use, the present invention quickly heats the sealed column box through a blower motor, and uses the first and second temperature-measuring resistors arranged inside the column box to monitor the temperature in different areas of the column box in real time, and sends the data measured by the temperature-measuring resistor sensor to the microcontroller in the electrical box. The signal of the temperature-measuring resistor sensor is converted and then the voltage across the heating resistor is controlled by a thyristor, so as to realize the control of the temperature and heat preservation in the column box. The microcontroller analyzes the received temperature data in real time, judges whether the blower motor needs to be started to continue heating or the cooling motor needs to be started to cool down in the current column box. At the same time, the microcontroller triggers the opening amplitude of the heat dissipation ventilation channel through thermal inertia to suppress the continuous action of thermal inertia, so that the temperature in the column box reaches the specified temperature range, and the control accuracy is required to reach ±0.1°C.

[0097] The microcontroller realizes two-way communication with the communication module. The microcontroller sends the temperature data collected by the temperature-measuring resistor to the resistance heater after data processing by the A / D converter, optoelectronic isolator, drive circuit, D / A converter, and high-power operational amplifier circuit. The data of the resistance heater is then fed back to the microcontroller after passing through the temperature conversion module, high-power operational amplifier circuit, D / A converter, optoelectronic isolation circuit, and A / D converter, so as to realize the control of the temperature. At the same time, the microcontroller sends the collected data to the data storage module for storage; the microcontroller also controls the drive of the blower motor and the cooling motor through an optocoupler and the corresponding drive circuit to keep the temperature control in the column box within the specified range.

[0098] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chromatographic column temperature control device for a chromatograph, characterized in that: It includes a column box body (1), the column box body (1) is a box body sealed on all sides, and a column box heat insulation layer (2) is arranged inside the column box body (1); Inside the column box body (1), there are a first temperature measuring resistance sensor (3), a chromatographic column (4), a heating device (5), a second temperature measuring resistance sensor (6), a heat dissipation motor (7), a blower motor (8) and an electrical control box (9). At the bottom of the column box body (1), there is a heat dissipation port, and a hollowed-out heat dissipation fin is also arranged at the position of the heat dissipation port; The chromatographic column (4) is arranged in the middle of the column box body (1) through a bracket. A first temperature measuring resistance sensor (3) is arranged above the chromatographic column (4), and a heating device (5) is arranged below the chromatographic column (4); The heat dissipation motor (7) is arranged at the heat dissipation port of the column box body (1), and a second temperature measuring resistance sensor (6) is also arranged inside the heat dissipation port of the column box body (1); The blower motor (8) is arranged below the heating device (5); Inside the chromatographic column (4), there is a resistance heating element (10); The electrical control box (9) is fixed on the bottom surface of the column box body (1) by screws. Inside the electrical control box (9), there is a control circuit board. The control circuit board integrates a microcontroller (11) and peripheral circuits. The peripheral circuits include an AD / DA conversion module (12), an opto-isolation module (13), a power operational amplifier module (14), and a motor drive module (15). The microcontroller (11) is connected to the resistance heating element (10) in series through the AD / DA conversion module (12), the opto-isolation module (13), and the power operational amplifier module (14) in sequence. The signal output end of the microcontroller (11) is connected to the blower motor (8) and the heat dissipation motor (7) through the motor drive module (15); The microcontroller (11) is also connected to a data communication module (18) and a data storage module (19); The power input end of the microcontroller (11) is connected to a power supply module (20); The first temperature measuring resistance sensor (3) and the second temperature measuring resistance sensor (6) are connected to the signal input end of the microcontroller (11) through wires; The chips used in the power operational amplifier module (14) are a control chip U7, an inverting amplifier U8, and an inverting amplifier U9; The circuit structure of the power operational amplifier module (14) is: Pin 1 of the control chip U7 and pin 12 of the control chip U7 are connected to the signal output end of the resistance heating element (10); Pins 2 to 6 of the control chip U7 are connected to each other and then grounded; Pin 7 of the control chip U7 is connected to one end of a capacitor C30 and then connected to the +5V power supply; Pin 8 of the control chip U7 is connected to the other end of the capacitor C30 and then grounded; Pin 9 of the control chip U7 is connected to pin 13 of the control chip U7 and then grounded; Pin 14 of the control chip U7 is connected to one end of a resistor R19. The other end of the resistor R19 is connected to one end of a resistor R20 and then connected to pin 3 of the inverting amplifier U9; The 15th pin of the control chip U7 is connected to one end of the resistor R16. The other end of the resistor R16 is connected to the 4th pin of the inverting amplifier U9 after being connected in parallel with one end of the resistor R14. The other end of the resistor R14 is connected to the 1st pin of the inverting amplifier U9 after being connected in parallel with one end of the resistor R17; The 16th pin of the control chip U7 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C22; The 2nd pin of the inverting amplifier U9 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C29; The 5th pin of the inverting amplifier U9 is connected to the +5V power supply after being connected in parallel with one end of the capacitor C26; The other end of the resistor R17 is connected to one end of the resistor R18 after being connected in parallel with one end of the capacitor C19; The other end of the resistor R18 is connected to the 3rd pin of the inverting amplifier U8 after being connected in parallel with one end of the capacitor C27; The other end of the capacitor C19 is connected to the 1st pin of the inverting amplifier U8 after being connected in parallel with one end of the resistor R13; The other end of the resistor R13 is connected to the 4th pin of the inverting amplifier U8 after being connected in parallel with one end of the resistor R12; The 2nd pin of the inverting amplifier U8 is connected to the -5V power supply after being connected in parallel with one end of the capacitor C28; The 5th pin of the inverting amplifier U8 is connected to the +5V power supply after being connected in parallel with one end of the capacitor C23; The models of the first temperature-measuring resistance sensor (3) and the second temperature-measuring resistance sensor (6) are PT100; The model of the control chip used inside the microcontroller (11) is STM32F103C8T6; The model used inside the opto-isolation module (13) is PC817; The model of the control chip U7 used in the power operational amplifier module (14) is ADG733, and the models of the inverting amplifier U8 and the inverting amplifier U9 are AD8628; The resistance heating element (10) is specifically a 220W heating resistor controlled by a triac; A method for controlling using a chromatographic column temperature control device of a chromatograph includes the following steps: Step 1: Start the chromatograph. The microcontroller (11) controls the temperature-measuring resistance sensor to work, collect the current temperature data inside the column oven in real time, and feedback the collected data to the microcontroller (11); Step 2: The microcontroller (11) analyzes and processes the temperature data, displays the result on the display screen, calculates the temperature difference and change rate through a preset temperature threshold, calculates the compensated temperature data through an algorithm, and the temperature control mathematical model is: ； Where: Td is the inertia time constant, Kd is the amplification coefficient, t is the lag time constant, and s is the complex variable; The signal is converted and then controls the voltage across the resistance heating element (10) through a thyristor; Step 3: The microcontroller (11) processes the temperature compensation data, converts it into corresponding heating drive frequencies and motor output pulse signals, and is used to control the cooling motor (7) and the blower motor (8) for corresponding temperature control; Step 4: The controlled temperature is collected in real time by the temperature-measuring resistance sensor, and the temperature data is fed back to the microcontroller. The microcontroller ensures that the current temperature is within the controlled temperature range and then finishes the processing and ends the control.

Images