A fast temperature control method and system

Abstract

The present invention provides a rapid temperature control method and system. The rapid temperature control method includes: using a cascade PID model to control the power of the temperature control system during the heating-up stage. Among them, the outer-loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, and the inner-loop algorithm of the cascade PID model controls the temperature change rate of the temperature control system. Introducing the cascade PID model to control the power of the temperature control system during the heating-up stage, cascade PID control can improve the object characteristics, has a relatively rapid and strong ability to overcome disturbances entering the secondary loop, and can eliminate the influence of the non-linear characteristics of the secondary loop. Furthermore, it can make rapid heating possible, improve the control accuracy and heating efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature control, and particularly relates to a rapid temperature control method and system. Background Art

[0002] In the field of biochemistry, precise temperature control of the reaction solution in the reaction tube is required to meet the normal biochemical reactions in the reaction solution. Such processes often involve frequent switching between multiple temperature ranges. Therefore, in order to save the time of biochemical reactions, improving the temperature change speed and temperature control accuracy are urgent problems to be solved.

[0003] At present, the commonly used temperature control device is a thermoelectric cooler (TEC). By applying positive and negative currents to both ends of the TEC, heating or cooling is achieved, and then heat or cold is transferred to the temperature control base where the reaction tube is placed through a solid heat conduction medium (such as a heat conduction metal block), so as to control the temperature of the metal objects (such as reagents, biological samples, chemical reaction solutions, etc.) in the reaction tube. However, at present, this solution has a large thermal resistance effect and a slow temperature change speed, and cannot meet the rapid heating and cooling adjustment.

[0004] Therefore, developing a temperature control device and method with high temperature control accuracy and fast temperature change speed has profound practical value and application prospects in many fields such as infectious disease prevention and control, biochemistry, and drug preparation. Summary of the Invention

[0005] In view of the above defects or deficiencies, the present invention provides a rapid temperature control method and system, aiming to solve the technical problems of low temperature control accuracy and slow temperature change speed in the current temperature control solution.

[0006] To achieve the above object, in the first aspect of the present invention, a rapid temperature control method is provided. The rapid temperature control method includes: in the heating stage, a cascade PID model is used to control the power of the temperature control system, wherein the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, and the inner loop algorithm of the cascade PID model controls the temperature change speed of the temperature control system.

[0007] In an embodiment of the present invention, the cascade PID model is tuned with a preset transfer function, wherein the preset transfer function is obtained by performing a Laplace transform on the temperature change expression of the temperature control system.

[0008] In an embodiment of the present invention, the rapid temperature control method further includes:

[0009] Obtain the preset transfer functions of the electromagnetic heating device and the first cooling device respectively, where the preset transfer function of the electromagnetic heating device is set to be obtained by performing Laplace transform on the temperature change expression of the electromagnetic heating device during the heating process, and the preset transfer function of the first cooling device is set to be obtained by performing Laplace transform on the temperature change expression of the first cooling device during the cooling process;

[0010] In the heating-up stage, use the cascade PID model to control the power of the electromagnetic heating device and the first cooling device. Among them, the outer-loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, and the inner-loop algorithm of the cascade PID model controls the temperature change rate of the temperature control system, and use the preset transfer function to tune the parameters of the cascade PID model.

[0011] In the embodiment of the present invention, the rapid temperature control method further includes:

[0012] In the cooling-down stage, turn off the electromagnetic heating device and adjust the power of the first cooling device to the maximum.

[0013] In the embodiment of the present invention, after turning off the electromagnetic heating device and adjusting the power of the first cooling device to the maximum in the cooling-down stage, it further includes;

[0014] When the current temperature is less than the first preset temperature control temperature, control the first cooling device to stop power output and enter the waiting time;

[0015] When the current temperature rises to be greater than the second preset temperature control temperature and less than the cooling-down target temperature, control to start the electromagnetic heating device for heating or constant temperature to control until the current temperature reaches the cooling-down target temperature.

[0016] In the embodiment of the present invention, the rapid temperature control method further includes:

[0017] In the heating and constant temperature stage, if the current temperature of the temperature control system does not exceed the heating-up target temperature, use the cascade PID model to control the temperature of the temperature control system. If the current temperature of the temperature system exceeds the heating-up target temperature, control to start the second cooling device for cooling.

[0018] In the embodiment of the present invention, the rapid temperature control method further includes:

[0019] Perform inertia correction on the cascade PID model.

[0020] In the embodiment of the present invention, the outer-loop algorithm of the cascade PID model is:

[0021]

[0022] The inner-loop algorithm of the cascade PID model is:

[0023]

[0024] Among them, k is the sampling serial number; u(k) is the outer-loop control quantity at the k-th moment; {K p , K i , K d} are the outer-loop coefficients; ΔT(k) is the temperature difference between the current temperature and the temperature-rising target temperature of the temperature control system at the k-th moment; ΔT ～ is the temperature difference between the current k-th moment and the (k - 1)-th moment; u(k)' is the inner-loop control quantity at the k-th moment; {K p ', K i ', K d '} are the inner-loop coefficients; ΔT v (k) is the temperature change rate of the temperature control system at the current k-th moment; ΔT v (k) ～ is the difference in temperature change rate between the current k-th moment and the (k - 1)-th moment; i is the integral formula serial number; a is the correction coefficient, and a = 1 to 2.5.

[0025] In the embodiment of the present invention, when the temperature difference ΔT between the current temperature and the temperature-rising target temperature of the temperature control system is less than or equal to the first preset value: K p = 10 to 14, K i = (2 to 4)K p , K d = (2 to 4)K p , K p ' = 600 to 750, K' i = (3 to 5)K' p , K' d = (3 to 5)K' p ;

[0026] When the temperature difference ΔT is greater than the first preset value and less than or equal to the second preset value: K p = 12 to 18, K i = (2 to 4)K p , K d = (0.2 to 0.6)K p , K p ' = 1000 to 1500, K' i = (3 to 6)K' p , K' d = (0.5 to 0.8)K' p ;

[0027] When the temperature difference ΔT is greater than the second preset value, both the outer-loop coefficients and the inner-loop coefficients take the maximum values.

[0028] In the embodiment of the present invention, the preset transfer function of the electromagnetic heating device:

[0029]

[0030] Preset transfer function of the first cooling device:

[0031]

[0032] Wherein, s is the expression after the Laplace transform of the temperature difference Δt.

[0033] In the embodiments of the present invention, the fast temperature control method further includes:

[0034] S1: Construct a temperature control system including an electromagnetic heating device, a first cooling device and a second cooling device;

[0035] S2: Respectively obtain the temperature change expressions of the electromagnetic heating device and the first cooling device, and perform Laplace transform on the temperature change expressions, and then respectively obtain the transfer functions of the heating process and the cooling process;

[0036] S3: Adopt segmented cascade PID to control the heating section, constant temperature section and cooling section of the temperature control system. Specifically:

[0037] The control method for the heating section is: Adopt cascade PID to control the power of the electromagnetic heating device and the first cooling device. Among them, the outer loop algorithm of the cascade PID controls the temperature difference of the temperature control system, the inner loop algorithm of the cascade PID controls the temperature change rate of the temperature control system, and the transfer function is used for the parameter tuning of the cascade PID;

[0038] The control method for the constant temperature section is: If there is no temperature overshoot in the temperature control system, then adopt cascade PID for control. If there is a temperature overshoot, then start the second cooling device for cooling;

[0039] The control method for the cooling section is: Turn off the electromagnetic heating device and adjust the power of the first cooling device to the maximum. If the current temperature is less than λT s , then turn off the first cooling device and wait. If the temperature rises back to σT s , then start the electromagnetic heating device for heating or constant temperature. T s is the target temperature, λ = 0.6 - 0.8, σ = 0.8 - 1.

[0040] To achieve the above object, the second aspect of the present invention also provides a fast temperature control system. Among them, the fast temperature control system includes:

[0041] A temperature control base for placing a reaction tube;

[0042] An electromagnetic heating device provided on the temperature control base and used for heating the temperature control base;

[0043] A first cooling device provided on the temperature control base and used for cooling the temperature control base;

[0044] A controller, which is communicatively connected to the electromagnetic heating device and the first cooling device respectively, and is configured to:

[0045] In the heating stage, a cascade PID model is adopted to control the power of the electromagnetic heating device and the first cooling device. Among them, the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control base, and the inner loop algorithm of the cascade PID model controls the temperature change rate of the temperature control base.

[0046] In the embodiment of the present invention, the first cooling device is set as fluid convection cooling, and the fluid flow rate is controlled by a fluid pump. The controller is further configured to:

[0047] In the cooling stage, the electromagnetic heating device is turned off and the power of the fluid pump is adjusted to the maximum.

[0048] In the embodiment of the present invention, the fast temperature control system further includes a second cooling device communicatively connected to the controller. The second cooling device is set as a fan. The controller is further configured to:

[0049] In the heating and constant temperature stage, if the current temperature of the temperature control base does not exceed the heating target temperature, a cascade PID model is adopted to control the temperature of the temperature control base. If the current temperature of the temperature control base exceeds the heating target temperature, the second cooling device is controlled to start for cooling.

[0050] In the embodiment of the present invention, the controller is further configured to execute the fast temperature control method described above.

[0051] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the fast temperature control method and system provided by the present invention mainly have the following beneficial effects:

[0052] 1. By reasonably controlling the heating device and the cooling device of the temperature control system through the cascade PID model, the present invention can overcome the large temperature inertia brought by rapid heating, make rapid heating and cooling possible, and realize rapid and accurate temperature control.

[0053] 2. The cascade PID of the present invention is different from the traditional cascade PID algorithm. An inertia correction formula for controlling the outer loop algorithm is added, which can effectively suppress control overshoot, and finally achieve the leading heating and cooling speeds (heating speed reaches 15.14 °C / s, cooling speed reaches 13.78 °C / s) and temperature control accuracy (±0.1 °C) in the industry.

[0054] 3. System identification of a highly nonlinear system is carried out based on the digital twin method, and a transfer function more in line with the actual system is derived.

[0055] 4. The temperature of the temperature control base is controlled for heating and cooling by adopting electromagnetic heating and fluid refrigeration methods, which can effectively reduce the thermal resistance and has a high heat transfer efficiency.

[0056] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Description of the Drawings

[0057] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings. In the drawings:

[0058] Figure 1 Schematically shows a flowchart of a rapid temperature control method in an embodiment of the present invention;

[0059] Figure 2 Schematically shows a structural diagram of a rapid temperature control system in an embodiment of the present invention;

[0060] Figure 3 Schematically shows the actual temperature curve of a rapid temperature control system in an embodiment of the present invention.

[0061] Description of the reference numerals in the drawings: 1, temperature control base; 1-1, temperature sensor; 2, electromagnetic heating device; 2-1, heating plate; 2-2, disc coil; 2-3, inverter; 3, second cooling device; 4, first cooling device; 4-1, liquid cooling head; 4-2, constant temperature box; 4-3, fluid pump; 4-4, pipeline; 5, reaction tube. Specific Embodiments

[0062] The following will describe in detail the specific embodiments of the present invention with reference to the drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0063] The first aspect of the present invention provides a rapid temperature control method, which can achieve rapid and precise temperature control. Among them, the rapid temperature control method includes:

[0064] In the heating stage, a cascade PID model is used to control the power of the temperature control system. Among them, the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, and the inner loop algorithm of the cascade PID model controls the temperature change rate of the temperature control system.

[0065] Due to the highly non-linear characteristics of the temperature control in PCR, it is difficult to control it through an accurate transfer function. Therefore, a cascade PID model is introduced to control the power of the temperature control system during the heating stage. The cascade PID control can improve the object characteristics, has a faster and stronger ability to overcome the disturbances entering the secondary loop, and can eliminate the influence of the non-linear characteristics of the secondary loop. As a result, rapid heating becomes possible, and the control accuracy and heating efficiency are improved.

[0066] Specifically, the PCR detection process generally includes a heating stage, a heating and constant temperature stage, and a cooling stage. The cascade PID control can occur either only in the heating stage or throughout the entire detection process.

[0067] In the embodiment of the present invention, the cascade PID model uses a preset transfer function for parameter tuning. Among them, the preset transfer function is obtained by performing a Laplace transform on the temperature change expression of the temperature control system. That is, in the cascade PID model of the present invention, a mathematical model is selected for parameter tuning. Compared with the empirical method and the trial-and-error method, it is significantly faster, more convenient, and more accurate. Specifically, the temperature change expression is the difference expression between the current temperature and the temperature at the previous moment.

[0068] Figure 1 Schematically shows the flowchart of the rapid temperature control method in an embodiment of the present invention. As Figure 1 shown, in the embodiment of the present invention, the rapid temperature control method further includes:

[0069] Step S100, respectively obtain the preset transfer functions of the electromagnetic heating device 2 and the first cooling device 4. Among them, the preset transfer function of the electromagnetic heating device 2 is set to be obtained by performing a Laplace transform on the temperature change expression of the electromagnetic heating device 2 during the heating process, and the preset transfer function of the first cooling device 4 is set to be obtained by performing a Laplace transform on the temperature change expression of the first cooling device 4 during the cooling process;

[0070] Step S200, during the heating stage, use the cascade PID model to control the power of the electromagnetic heating device 2 and the first cooling device 4. Among them, the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, the inner loop algorithm of the cascade PID model controls the temperature change rate of the temperature control system, and the preset transfer function is used to tune the parameters of the cascade PID model.

[0071] Understandably, the aforementioned temperature control system includes an electromagnetic heating device 2 and a first cooling device 4. The electromagnetic heating device 2 is used to heat the temperature control system, and the first cooling device 4 is used to cool the temperature control system. Moreover, an expression of the temperature change during the heating process of the electromagnetic heating device 2 and an expression of the temperature change during the cooling process of the first cooling device 4 are pre-constructed, so that when performing cascade PID control, a preset transfer function obtained by Laplace-transforming the temperature change expression can be used for parameter tuning.

[0072] It should be particularly noted that during the heating-up stage, although the first cooling device 4 can adopt cascade PID model control, under normal heating-up conditions, the cascade PID control of the first cooling device 4 can be not started. Only under abnormal heating-up conditions will the cascade PID control of the first cooling device 4 be started. Of course, the present invention is not limited to this. It is also possible to start the cascade PID control of both the electromagnetic heating device 2 and the first cooling device 4 during the heating-up stage.

[0073] See Figure 1 , in the embodiment of the present invention, the rapid temperature control method further includes:

[0074] Step S400, in the cooling-down stage, turn off the electromagnetic heating device 2 and adjust the power of the first cooling device 4 to the maximum.

[0075] Understandably, when entering the cooling-down stage, the power output of the electromagnetic heating device 2 can be first controlled, and the first cooling device 4 can be controlled to output at full power, so as to achieve rapid cooling.

[0076] In the embodiment of the present invention, after step S400, that is, in the cooling-down stage, after turning off the electromagnetic heating device 2 and adjusting the power of the first cooling device 4 to the maximum, it further includes;

[0077] When the current temperature is less than the first preset temperature control value, control the first cooling device 4 to stop power output and enter the waiting time;

[0078] When the current temperature rises to be greater than the second preset temperature control value and less than the cooling-down target temperature, control to start the electromagnetic heating device 2 for heating or maintaining a constant temperature, so as to control until the current temperature reaches the cooling-down target temperature.

[0079] Specifically, in the cooling stage, the first cooling device 4 can be controlled to operate at the maximum power until the current temperature of the temperature control system drops to the first preset temperature control temperature. It should be noted that both the first preset temperature control temperature and the subsequent second preset temperature control temperature are set to be less than the target temperature in the cooling stage. This is because of the existence of thermal inertia. If the temperature is directly reduced to the cooling target temperature, the subsequent temperature will rise. Therefore, the "overshoot - callback" control logic can be adopted to eliminate the thermal resistance. After the temperature drops to the first preset temperature control temperature, the first cooling device 4 is controlled to stop power output and enter the waiting time to wait for the temperature control system to warm up. When the current temperature of the temperature control system rises to be greater than the second preset temperature control temperature and less than the cooling target temperature, the electromagnetic heating device 2 is controlled to start and perform heating control or constant temperature control until the current temperature of the temperature control system reaches the cooling target temperature, so as to eliminate the influence of thermal inertia in the cooling process and ensure that the subsequent cooling target temperature is stably maintained.

[0080] More specifically, the first preset temperature control temperature can be set to λT s2 , and the second preset temperature control temperature can be set to σT s2 , where T s2 is the cooling target temperature, and the value range of λ is 0.6 < λ < 0.8, 0.8 < σ < 1.

[0081] Please refer to again Figure 1 , in the embodiment of the present invention, the rapid temperature control method further includes:

[0082] Step S300, in the heating and constant temperature stage, if the current temperature of the temperature control system does not exceed the heating target temperature, the cascade PID model is used to control the temperature of the temperature control system. If the current temperature of the temperature system exceeds the heating target temperature, the second cooling device 3 is controlled to start for cooling.

[0083] Furthermore, in the heating and constant temperature stage, in addition to the electromagnetic heating device 2 and the first cooling device 4 using the cascade PID model to participate in the control, the second cooling device 3 can also be added to facilitate rapid cooling control when the temperature overshoots. It should be noted that the first cooling device 4 can be liquid - cooled convection cooling, and the second cooling device 3 preferably uses air - cooled convection cooling, such as a fan. In addition, the cascade PID control of the first cooling device 4 may not be started in the heating and constant temperature stage. Then, in the heating and constant temperature stage, it can be set as the comprehensive control of the electromagnetic heating device 2 and the second cooling device 3.

[0084] Even further, the specific control logic in the heating and constant temperature stage is as follows:

[0085] If the temperature difference ΔT between the current temperature of the temperature control system and the target temperature for temperature increase is > 0, that is, there is no overshoot, the above cascade PID control is adopted; if ΔT < 0, that is, there is a temperature overshoot, the second cooling device 3, that is, the fan, is turned on for cooling. The fan speed should be controlled to satisfy the following formula:

[0086] V fan = aΔT 2 - bΔT

[0087] Among them, the value range of a can be 0.5 to 1.5, and the value range of b can be 0.8 to 1.2.

[0088] In the embodiment of the present invention, the fast temperature control method further includes:

[0089] Performing inertia correction on the cascade PID model.

[0090] It can be understood that when constructing the cascade PID model, an inertia correction formula for controlling the outer loop algorithm can be added, so that the cascade PID of the present invention is different from the traditional cascade PID algorithm, and can effectively suppress control overshoot, and finally achieve the leading heating and cooling speeds (heating speed up to 15.14 °C / s, cooling speed up to 13.78 °C / s) and temperature control accuracy (±0.1 °C) in the industry.

[0091] In the embodiment of the present invention, the outer loop algorithm of the cascade PID model is:

[0092]

[0093] The inner loop algorithm of the cascade PID model is:

[0094]

[0095] Among them, k is the sampling sequence number; u(k) is the outer loop control quantity at the k-th moment; {K p 、K i 、K d} are the outer loop coefficients; ΔT(k) is the temperature difference between the current temperature of the temperature control system and the target temperature for temperature increase at the k-th moment; ΔT ～ is the temperature difference between the current k-th moment and the (k - 1)-th moment; u(k)' is the inner loop control quantity at the k-th moment; {K p ′、K i ′、K d ′} are the inner loop coefficients; ΔT v (k) is the temperature change rate of the temperature control system at the current k-th moment; ΔT v (k) ～ is the difference in temperature change rate between the current k-th moment and the (k - 1)-th moment; i is the integral formula sequence number; a is the correction coefficient, a = 1 to 2.5.

[0096] Specifically, before using the cascade PID model to control the power of the temperature control system in the heating-up stage, it further includes:

[0097] Reading the current temperature T detected by the temperature sensor 1-1 c , where the temperature sensor 1-1 is arranged on the temperature control base 1 of the temperature control system;

[0098] Comparing the current temperature T c with the heating target temperature T s1 , and calculating the temperature difference ΔT and the temperature change rate T v .

[0099] In the embodiment of the present invention, when the temperature difference ΔT between the current temperature and the heating target temperature of the temperature control system is less than or equal to the first preset value: K p = 10 - 14, K i = (2 - 4)K p , K d = (2 - 4)K p , K p ' = 600 - 750, K' i = (3 - 5)K' p , K' d = (3 - 5)K' p ;

[0100] When the temperature difference ΔT is greater than the first preset value and less than or equal to the second preset value: K p = 12 - 18, K i = (2 - 4)K p , K d = (0.2 - 0.6)K p , K p ' = 1000 - 1500, K' i = (3 - 6)K' p , K' d = (0.5 - 0.8)K' p ;

[0101] When the temperature difference ΔT is greater than the second preset value, both the outer loop coefficient and the inner loop coefficient take the maximum value.

[0102] Specifically, the first preset value of the temperature difference ΔT is 5, and the second preset value is 15. The above cascade PID model needs to meet the following segmented threshold criteria:

[0103] (1) If the temperature difference ΔT ≤ 5, set the PID control parameter as P L ;

[0104] (2) If the temperature difference 5 < ΔT ≤ 15, set the PID control parameter as P M ;

[0105] (3) If the temperature difference ΔT > 15, set the PID control parameters to P H .

[0106] Among them, P L , P M , P H are the PID tuning parameters under different threshold conditions respectively. The parameter tuning method is as follows: First, construct a simulation model according to the following transfer functions G(s) and G(s)' in the control toolbox of Matlab software, and perform parameter simulation adjustment, and then further fine-tune the control parameters according to the actual situation in the actual control system. The specific details are shown in the following table:

[0107]

[0108] Table 1

[0109] Among them, the specific correlation coefficients between the proportional, integral, and differential coefficients can be adjusted according to the actual control situation; Max represents the maximum selectable parameter at this time, which can be set according to the maximum power of the actual device.

[0110] In the embodiment of the present invention, the preset transfer function of the electromagnetic heating device 2:

[0111]

[0112] The preset transfer function of the first cooling device 4:

[0113]

[0114] Among them, s is the expression after the Laplace transform of the temperature difference Δt.

[0115] Furthermore, analyze the experimental physical model, and perform model derivation according to the electromagnetic and convective heat transfer theories to obtain the temperature change expression under the electromagnetic heating state as:

[0116]

[0117] Among them, l is the thickness of the heating metal plate, d is the diameter of the heating metal plate, f is the electromagnetic frequency, n is the number of turns of the heating coil, μ 0 is the vacuum permittivity, P 0 is the electromagnetic heating power, λ is the thermal conductivity of the heating metal plate, A is the area of the heating metal plate, R is the diameter of the heating coil, r is the distance between the heating metal plate and the heating coil, m is the mass of the heating metal plate, ρ is the resistivity of the heating metal plate, and k and π are constant terms.

[0118] The temperature change expression under the convective cooling state is:

[0119]

[0120] Among them, h is the convective heat transfer coefficient, A is the contact surface area, and T c is the current temperature of the temperature control base 1, and T w is the coolant temperature, c is the specific heat capacity, and m is the mass of the temperature control base 1.

[0121] According to the above-derived formula, a digital twin system is constructed using finite element simulation software, and system identification is performed on the electromagnetic heating and convective cooling processes under simulation data, so as to obtain the system transfer function under different states.

[0122] In summary, the fast temperature control method provided by the present invention includes the following steps:

[0123] (1). Construct a temperature control system for controlling the temperature of the reaction tube 5. The temperature control system includes an electromagnetic heating device 2, a first cooling device 4, and a second cooling device 3;

[0124] (2). Obtain the preset transfer functions of the electromagnetic heating device 2 and the first cooling device 4 respectively. Among them, the preset transfer function of the electromagnetic heating device 2 is set to be obtained by performing Laplace transform on the temperature change expression of the electromagnetic heating device 2 during the heating process, and the preset transfer function of the first cooling device 4 is set to be obtained by performing Laplace transform on the temperature change expression of the first cooling device 4 during the cooling process;

[0125] (3). Adopt segmented control for the heating-up stage, heating-up constant temperature stage, and cooling-down stage of the temperature control system. Specifically:

[0126] Heating-up stage control method: Use a cascade PID model to control the power of the electromagnetic heating device 2 and the first cooling device 4. Among them, the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, and the inner loop algorithm of the cascade PID model controls the temperature change rate of the temperature control system, and the preset transfer function is used to tune the parameters of the cascade PID model;

[0127] Heating-up constant temperature stage control method: If the current temperature of the temperature control system does not exceed the heating-up target temperature, use a cascade PID model to control the temperature of the temperature control system. If the current temperature of the temperature system exceeds the heating-up target temperature, control to start the second cooling device 3 for cooling;

[0128] Cooling-down stage control method: Turn off the electromagnetic heating device 2 and adjust the power of the first cooling device 4 to the maximum. If the current temperature is less than λT s2 , turn off the first cooling device 4 and enter the waiting time. If the current temperature rises back to σT s2 , start the electromagnetic heating device 2 for heating control or constant temperature control, T s2is the target temperature for temperature reduction, λ = 0.6 to 0.8, σ = 0.8 to 1.

[0129] As Figure 2 shown, to achieve the above object, the second aspect of the present invention further provides a rapid temperature control system, wherein the rapid temperature control system includes:

[0130] A temperature control base 1 for placing a reaction tube 5;

[0131] An electromagnetic heating device 2 provided on the temperature control base 1 and used to heat the temperature control base 1;

[0132] A first cooling device 4 provided on the temperature control base 1 and used to cool the temperature control base 1;

[0133] A controller, communicatively connected to the electromagnetic heating device 2 and the first cooling device 4 respectively, and configured to:

[0134] In the heating-up stage, a cascade PID model is used to control the power of the electromagnetic heating device 2 and the first cooling device 4. Among them, the outer-loop algorithm of the cascade PID model controls the temperature difference of the temperature control base 1, and the inner-loop algorithm of the cascade PID model controls the temperature change rate of the temperature control base 1.

[0135] When using the above temperature control system, since the heating device selects the electromagnetic heating device 2, it is possible to directly heat the temperature control base 1, avoiding heat loss. And compared with the existing contact heating methods such as semiconductor heating and oil bath, the present invention adopts a non-contact electromagnetic heating scheme, which can effectively reduce the thermal resistance and achieve efficient heat transfer (the heat transfer efficiency is as high as more than 90%, and the heating speed is higher than 15 °C / s). In addition, the controller uses a cascade PID model to control the electromagnetic heating device 2 and the first cooling device 4, which makes it possible to rapidly heat up, so as to achieve the purpose of improving the control accuracy and heating efficiency.

[0136] Specifically, the electromagnetic heating device 2 includes a heating plate 2-1, a disc coil 2-2, and an inverter 2-3. The heating plate 2-1 is attached to the lower end of the temperature control base 1, and a thermal conductive silicone grease material is filled therebetween to ensure good heat conduction effect. The disc coil 2-2 is disposed at the lower end of the heating plate 2-1 and maintains a spacing of 1 mm. The inverter 2-3 is used to provide alternating current for the disc coil 2-2. The alternating current generated by the inverter 2-3 enables the disc coil 2-2 to excite an alternating magnetic field, and further enables the heating plate 2-1 to generate an electromagnetic heating effect. Preferably, the inverter 2-3 can invert direct current of 36V - 54V into alternating current of about 180 kHz to achieve a better heating power. The inverter 2-3 can invert low-voltage direct current into high-frequency alternating current. When the frequency of the high-frequency alternating current is f = 80 kHz, the maximum heating power can be obtained. The heating plate 2-1 is made of a metal conductor material with high magnetic permeability (μ > 7000), such as pure iron, ferrite, or iron-nickel alloy. And the thickness of the heating plate 2-1 is preferably 1 mm, which not only has a high heating efficiency but also prevents excessive thermal inertia.

[0137] It should be particularly noted that the outer loop algorithm and the inner loop algorithm of the cascade PID model are as described above, and will not be elaborated here too much.

[0138] In the embodiment of the present invention, the first cooling device 4 is set to fluid convection cooling, and the fluid flow rate is controlled by a fluid pump 4-3. The controller is further configured to:

[0139] In the cooling stage, turn off the electromagnetic heating device 2 and adjust the power of the fluid pump 4-3 to the maximum.

[0140] Furthermore, the interior of the temperature control base 1 is provided with a hollow structure for placing a temperature-controlled sample (reaction tube 5). The first cooling device 4 includes a liquid cooling head 4-1 sleeved outside the hollow structure. The liquid cooling head 4-1 and the outer wall of the temperature control base 1 enclose an annular cooling cavity. The liquid cooling head 4-1 is in close fit with the upper cylindrical surface of the temperature control base 1 to ensure the tightness of the fluid in the cooling cavity. And liquid inlets and outlets are respectively provided on the opposite sides of the liquid cooling head 4-1 in a one-to-one correspondence. The temperature sensor 1-1 is closely attached to the outer side wall of the temperature control base 1 to monitor the change of its wall temperature. The annular cooling cavity formed by the enclosure of the liquid cooling head 4-1 and the outer wall of the temperature control base 1 allows the coolant to flow through, and directly cools the temperature control base 1, avoiding heat loss. And compared with the existing cooling methods such as semiconductor refrigeration and air cooling, the present invention adopts a forced convection cooling method. By directly contacting the coolant with the temperature control base 1, the bottle body can be quickly cooled (the heat transfer thermal resistance is zero, and the cooling rate is higher than 12 °C / s).

[0141] Preferably, the temperature control base 1 is made of a material with a relatively high thermal conductivity and a relatively low specific heat capacity, such as aluminum or copper metal. The liquid cooling head 4-1 is made of a high heat distortion plastic, such as ABS engineering plastic, resin material, etc.

[0142] Furthermore, the first cooling device 4 further includes a thermostat 4-2, a fluid pump 4-3 and a pipeline 4-4. The thermostat 4-2, the fluid pump 4-3 and the cooling cavity are connected in series through the pipeline 4-4 to form a closed pipeline. The thermostat 4-2 can keep the temperature of the coolant inside it constant, and -5°C is a preferred choice. Specifically, the coolant in the thermostat 4-2 can be selected from various heat-conducting media such as deionized water, propylene glycol, heat-conducting oil, liquid metal, etc. Since deionized water has the advantages of high heat-conducting coefficient and being environmentally friendly and easily available, choosing deionized water as the coolant has a better refrigeration effect.

[0143] In the embodiment of the present invention, the rapid temperature control system further includes a second cooling device 3 communicatively connected to the controller. The second cooling device 3 is configured as a fan, and the controller is further configured to:

[0144] In the heating and constant temperature stage, if the current temperature of the temperature control base 1 does not exceed the heating target temperature, the temperature of the temperature control base 1 is controlled by using a cascade PID model. If the current temperature of the temperature control base 1 exceeds the heating target temperature, the second cooling device 3 is controlled to start for cooling.

[0145] It can be understood that the heating and constant temperature stage is a process in which the temperature control system maintains the set temperature and enters dynamic stability. The addition of the second cooling device 3 facilitates cooling when the temperature of the temperature control system overshoots, so that the current temperature of the temperature control system can fall back to the heating target temperature.

[0146] Therefore, the specific heating and cooling process of the rapid temperature control system provided by the present invention is implemented according to the following steps:

[0147] 1. Heating process

[0148] The heating process is a process in which the temperature control base 1 obtains external energy to rapidly increase the temperature. The heat transfer sequence includes: 1) The inverter 2-3 converts low-voltage direct current into high-frequency alternating current and excites an alternating magnetic field through the disc coil 2-2; 2) The heating disc 2-1 generates intense heat due to the electromagnetic heat effect and transfers the heat to the temperature control base 1 through the way of solid heat transfer; 3) The reaction tube 5 and the temperature of the internal reaction liquid rise.

[0149] 2. Constant temperature process

[0150] The constant temperature process is a process in which the temperature control base 1 maintains the set temperature in dynamic stability. It includes both obtaining heat through the heating disc 2-1 during electromagnetic heating and the process of dissipating heat through the fan.

[0151] 3. Cooling process

[0152] The cooling process is the process in which the temperature control base 1 releases heat to achieve rapid temperature reduction. The heat transfer sequence includes: 1) The coolant in the constant temperature box 4-2 circulates in the pipeline 4-4 under the action of the fluid pump 4-3; 2) The coolant in the cooling cavity flows around the outer cylindrical surface of the temperature control base 1; 2) Under forced convection cooling, the heat on the temperature control base 1 is transferred to the coolant, thereby reducing the temperature; 3) The temperature of the reaction tube 5 and the internal reaction liquid drops. In addition, in the cooling stage, to obtain the maximum cooling rate, the fluid pump 4-3 of the first cooling device 4 is in the maximum power state during the operation process, and the "overshoot - callback" control logic is adopted to eliminate the thermal resistance, specifically as follows: ① The opening of the fluid pump 4-3 is the largest to cool the temperature control base 1, and at this time, the electromagnetic heating device 2 is turned off.

[0153] ② If T c <λT s2 , turn off the fluid pump 4-3 and enter the waiting time.

[0154] ③ If the temperature rises back to T c >σT S2 , re-enter the heating state, and turn on the electromagnetic heating module for temperature increase or constant temperature control. Among them, the value range of λ is: 0.6 - 0.8, and the value range of σ is: 0.8 - 1.

[0155] As Figure 3 shown in the actual temperature control effect of the present invention, including the temperature increase stage, the temperature increase and constant temperature stage, and the temperature decrease stage. Through the sequential combination and cycle of these three stages, the final reaction control is achieved.

[0156] Tables 2 - 4 show the sampling results in the actual temperature control process of the present invention. By analyzing the data in the tables, it can be seen that the temperature increase rate of the present invention can reach 15.14 °C / s, the temperature decrease rate can reach 13.78 °C / s, and the temperature can be accurately controlled within ±0.1 °C.

[0157]

[0158]

[0159] Table 2

[0160]

[0161] Table 3

[0162]

[0163] Table 4

[0164] In summary, the fast temperature control method and system of the present invention can achieve fast heating and cooling control, greatly improving the heating and cooling speed during the reaction process, effectively shortening the detection time, and improving the reaction efficiency. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial application value.

[0165] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0166] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0167] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means implements the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0168] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0169] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0170] The memory may include non - permanent memory in the form of computer - readable media, random access memory (RAM) and / or non - volatile memory such as read - only memory (ROM) or flash RAM. The memory is an example of computer - readable media.

[0171] Computer - readable media includes permanent and non - permanent, removable and non - removable media and can store information by any method or technology. The information can be computer - readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase - change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read - only memory (ROM), electrically erasable programmable read - only memory (EEPROM), flash memory or other memory technologies, compact disc read - only memory (CD - ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non - transitory media that can be used to store information that can be accessed by a computing device. As defined herein, computer - readable media does not include transitory media such as modulated data signals and carrier waves.

[0172] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising the element.

[0173] The above are only embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A rapid temperature control method, characterized in that: The rapid temperature control method comprises: In the heating stage, a cascade PID model is used to control the power of the temperature control system, wherein the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, and the inner loop algorithm of the cascade PID model controls the temperature change speed of the temperature control system; The cascade PID model uses a preset transfer function for parameter tuning, wherein the preset transfer function is obtained by performing Laplace transformation on the temperature change expression of the temperature control system; The rapid temperature control method further comprises: respectively obtaining preset transfer functions of the electromagnetic heating device (2) and the first cooling device (4), wherein the preset transfer function of the electromagnetic heating device (2) is set to be obtained by performing Laplace transform on the temperature change expression of the electromagnetic heating device (2) during the heating process, and the preset transfer function of the first cooling device (4) is set to be obtained by performing Laplace transform on the temperature change expression of the first cooling device (4) during the cooling process; In the temperature rising stage, the cascade PID model is used to control the power of the electromagnetic heating device (2) and the first cooling device (4), wherein the outer loop algorithm of the cascade PID model controls the temperature difference of the temperature control system, the inner loop algorithm of the cascade PID model controls the temperature change speed of the temperature control system, and the preset transfer function is used to perform parameter tuning on the cascade PID model; The outer loop algorithm of the cascade PID model is: The inner loop algorithm of the cascade PID model is: Where k is the sampling number; u(k) is the outer loop control quantity at the kth moment; {K p , K i , K d } is the outer loop coefficient; ΔT(k) is the temperature difference between the current temperature of the temperature control system at the kth moment and the target temperature of the heating; ΔT ～ is the temperature difference between the current time k and time k-1; u(k) ′ is the inner loop control quantity at the kth moment; {K p ′ , K i ′ , K d ′ } is the inner loop coefficient; ΔT v (k) is the temperature change speed of the temperature control system at the current time k; ΔT v (k) ～ is the temperature change rate difference between the current time k and the time k-1; i is the integral number; a is the correction coefficient, a=1~2.

5.

2. The rapid temperature control method according to claim 1, characterized in that: The rapid temperature control method further comprises: During the temperature reduction phase, the electromagnetic heating device (2) is turned off and the power of the first cooling device (4) is adjusted to the maximum.

3. The rapid temperature control method according to claim 2, characterized in that: After shutting down the electromagnetic heating device (2) and adjusting the power of the first cooling device (4) to the maximum during the temperature reduction phase, the method further comprises: When the current temperature is lower than the first preset temperature control temperature, the first cooling device (4) is controlled to stop power output and enter a waiting time; When the current temperature rises to a temperature greater than the second preset temperature control temperature and less than the cooling target temperature, the electromagnetic heating device (2) is controlled to start heating or maintaining a constant temperature until the current temperature reaches the cooling target temperature.

4. The rapid temperature control method according to claim 1, characterized in that: The rapid temperature control method further comprises: In the stage of heating and maintaining constant temperature, if the current temperature of the temperature control system does not exceed the heating target temperature, the cascade PID model is used to control the temperature of the temperature control system; if the current temperature of the temperature system exceeds the heating target temperature, the second cooling device (3) is controlled to start cooling.

5. The rapid temperature control method according to claim 1, characterized in that: The rapid temperature control method further comprises: An inertia correction is performed on the cascade PID model.

6. The rapid temperature control method according to claim 1, characterized in that: When the temperature difference ΔT between the current temperature of the temperature control system and the heating target temperature is less than or equal to a first preset value: K p =10~14,K i =(2~4)K p , K d =(2~4)K p , K p ′=600~750,K′ i =(3~5)K′ p , K′ d =(3~5)K′ p ; When the temperature difference ΔT is greater than the first preset value and less than or equal to the second preset value: K p =12~18,K i =(2~4)K p , K d =(0.2~0.6)K p , K p ′=1000~1500,K′ i =(3~6)K′ p , K′ d =(0.5~0.8)K′ p ; When the temperature difference ΔT is greater than a second preset value, both the outer loop coefficient and the inner loop coefficient take a maximum value.

7. The rapid temperature control method according to claim 1, characterized in that: The preset transfer function of the electromagnetic heating device (2) is: The preset transfer function of the first cooling device (4) is: Where s is the expression of the temperature difference Δt after Laplace transformation.

8. The rapid temperature control method according to any one of claims 1 to 7, characterized in that: The rapid temperature control method further comprises: S1: constructing a temperature control system including an electromagnetic heating device, a first cooling device and a second cooling device; S2: respectively obtaining temperature change expressions of the electromagnetic heating device and the first cooling device, and performing Laplace transform on the temperature change expressions, thereby respectively obtaining transfer functions of the heating process and the cooling process; S3: Using segmented cascade PID to control the temperature rise section, constant temperature section and temperature drop section of the temperature control system, specifically: The temperature rise stage control method is: using the cascade PID to control the power of the electromagnetic heating device and the first cooling device, wherein the outer loop algorithm of the cascade PID controls the temperature difference of the temperature control system, the inner loop algorithm of the cascade PID controls the temperature change speed of the temperature control system, and the transfer function is used to perform parameter setting of the cascade PID; The constant temperature section control method is: if the temperature control system does not have a temperature overshoot, the cascade PID is used for control; if the temperature overshoot occurs, the second cooling device is started to cool down; The cooling stage control method is: turn off the electromagnetic heating device and adjust the power of the first cooling device to the maximum. If the current temperature is less than λT s , then turn off the first cooling device and wait. If the temperature rises back to σT s , then start the electromagnetic heating device to increase the temperature or keep the temperature constant, T s is the target temperature, λ=0.6~0.8, σ=0.8~1.

9. A rapid temperature control system, characterized in that: The rapid temperature control system comprises: A temperature control base (1) for placing a reaction tube (5); An electromagnetic heating device (2), arranged on the temperature control base (1) and used for heating the temperature control base (1); A first cooling device (4), arranged on the temperature control base (1) and used for cooling the temperature control base (1); A controller is communicatively connected to the electromagnetic heating device (2) and the first cooling device (4), respectively, and is configured to execute the rapid temperature control method according to any one of claims 1 to 8.

10. The rapid temperature control system according to claim 9, characterized in that: The first cooling device (4) is configured to perform fluid convection cooling, and the fluid flow rate is controlled by a fluid pump (4-3). The controller is further configured to: During the cooling phase, the electromagnetic heating device (2) is turned off and the power of the fluid pump is adjusted to the maximum.

11. The rapid temperature control system according to claim 9, characterized in that: The rapid temperature control system further comprises a second cooling device (3) communicatively connected to the controller, wherein the second cooling device (3) is configured as a fan, and the controller is further configured as follows: In the stage of heating and maintaining a constant temperature, if the current temperature of the temperature control base (1) does not exceed the heating target temperature, the cascade PID model is used to control the temperature of the temperature control base (1); if the current temperature of the temperature control base (1) exceeds the heating target temperature, the second cooling device (3) is controlled to start cooling the temperature.

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