A normalized hybrid high-precision temperature control method

Abstract

The application discloses a mixed high-precision temperature control method based on normalization, which comprises the following steps: obtaining a target temperature for temperature control according to a lower limit of a temperature control threshold and an upper limit of the temperature control threshold, calculating a normalized temperature deviation between an actual temperature value and the target temperature for temperature control, directly controlling an average expected output duty cycle of a heating loop according to the deviation, and controlling an actual output duty cycle of the heating loop by using a normalized PID+switch control mode. The application realizes high-precision active temperature control of a spacecraft, and has the advantages of high temperature control precision and easy adjustment of parameters.

Description

Technical Field

[0001] This invention relates to a normalized hybrid high-precision temperature control method for achieving high-precision temperature control of spacecraft, belonging to the field of temperature control technology. Background Technology

[0002] With the development of aerospace technology, some high-precision measurement components, such as optical sensors and accelerometers, have placed higher demands on temperature control accuracy. High-precision temperature control can provide a stable operating environment for the measurement components and reduce the impact of thermal deformation on their measurement accuracy. These high-precision measurement components have increasingly higher requirements for the accuracy and stability of temperature control, with some instruments requiring temperature control stability indicators better than the milliK level.

[0003] Spacecraft thermal control typically employs a combination of passive thermal control and active temperature compensation. To ensure the accuracy and stability of temperature control for critical instruments and equipment, higher demands are placed on active temperature control methods. Traditional on / off active temperature control methods cannot meet these high-precision requirements. For methods using common PID control to calculate the temperature control cycle, the ranges of proportional, integral, and derivative coefficients are difficult to determine, requiring continuous adjustments and experimentation. Furthermore, if the temperature control cycle changes, these coefficients must be readjusted. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects and provide a normalized hybrid high-precision temperature control method, which solves the technical problems of low temperature control accuracy and complex adjustment methods in the prior art. This invention realizes high-precision active temperature control for spacecraft and has the advantages of high temperature control accuracy and easy parameter adjustment.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A normalization-based hybrid high-precision temperature control method includes:

[0007] (1) Based on the preset lower limit of the temperature control threshold T min and the upper limit of temperature control threshold T max Obtain the target temperature T for temperature control target ;

[0008] (2) In the kth temperature control cycle, the actual temperature value T(k) of the controlled equipment is collected, k = 1, 2, 3, ...;

[0009] (3) Based on the lower limit of the temperature control threshold T min Temperature control threshold upper limit T max Temperature control target temperature T target The normalized temperature deviation e(k) for the k-th temperature control cycle is obtained by combining the actual temperature value T(k) of the controlled equipment:

[0010] e(k) = (T target - T(k)) x 2 / (T max - T min ) ;

[0011] (4) obtaining the integral error sumErr(k) of the kth temperature control period according to the normalized temperature deviation e(k) of the kth temperature control period and the integral error sumErr(k-1) of the previous k-1 temperature control periods;

[0012] (5) obtaining the expected output duty cycle DR(k) of the heating loop according to the normalized temperature deviation e(k) of the kth temperature control period and the integral error sumErr(k);

[0013] (6) controlling the output duty cycle of the heating loop to be DR(k);

[0014] (7) returning to step (2) in the k+1th temperature control period.

[0015] Further, in step (1), T target = (T min + T max ) / 2.

[0016] Further, in step (4), sumErr(k) = sumErr(k-1) + e(k);

[0017] The initial value of the integral error sumErr(0) = 0.

[0018] Further, in step (5), the method for obtaining the expected output duty cycle DR(k) of the heating loop according to the normalized temperature deviation e(k) of the kth temperature control period and the integral error sumErr(k) is as follows:

[0019] When e(k) ≥ 1, DR(k) = 100%;

[0020] If e(k) ≤ -1, DR(k) = 0%;

[0021] If -1 < e(k) < 1, the duty cycle is calculated by using the PID method.

[0022] Further, if -1 < e(k) < 1, the duty cycle is calculated by using the biased PID method, specifically as follows:

[0023] DR(k) = bias + Kp x e(k) + Ki x sumErr(k) + Kd x [e(k) - e(k-1)];

[0024] Wherein, Kp is a proportional coefficient, Ki is an integral coefficient, Kd is a differential coefficient, bias is a bias duty cycle, and is used to adjust the temperature control stability.

[0025] Further, the value range of Kp, Ki, Kd, and bias is 0-1.

[0026] Further, in step (6), if DR(k) > 100%, then DR(k) = 100%; if DR(k) < 0, then DR(k) = 0.

[0027] Further, step (5) is performed at the beginning of the kth temperature control cycle, and step (6) is performed in the kth temperature control cycle.

[0028] Further, in step (1), the temperature control target temperature T target is autonomously calculated by corresponding software according to a pre-set temperature control threshold lower limit T min and a temperature control threshold upper limit T max .

[0029] Further, the values of the temperature control threshold lower limit T min , the temperature control threshold upper limit T max , the bias duty cycle bias, the proportional coefficient Kp, the integral coefficient Ki, and the differential coefficient Kd are stored in a table form in a Flash / EEprom and a RAM, and are modified through remote control.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] (1) The present application is based on a normalized mixed high-precision temperature control method, and creatively based on a normalized temperature deviation calculation method, which effectively simplifies the temperature control process on the basis of ensuring temperature control precision.

[0032] (2) The present application meets the high-precision temperature control requirements of a spacecraft, autonomously calculates a temperature control target by setting a temperature control threshold upper and lower limit, and has the advantages of rapid convergence based on threshold temperature control and high precision based on PID temperature control.

[0033] (3) In the PID temperature control process of the present application, the proportional coefficient Kp, the integral coefficient Ki, and the differential coefficient Kd are normalized, and the value range is limited to 0-1, which is the proportion of each parameter, and the parameters are intuitive and easy to adjust; at the same time, different temperature control strategies can be realized through the setting of parameters such as the bias duty cycle bias, including: when bias is not equal to 0, it is a normalized bias PID; when bias is equal to 0, it is a normalized PID; when bias = 0.5, Kp = 0.5, Ki = 0, and Kd = 0, it is a normalized proportional temperature control method, which has the advantage of strong method universality.

[0034] (4) The calculation output in the application is directly the desired duty ratio DR(k) of the heating loop output, ranging from 0 to 1, and is not affected by the length change of the temperature control period. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A flowchart of a mixed high-precision temperature control method based on normalization according to the application. DETAILED DESCRIPTION

[0036] The characteristics and advantages of the application will become more apparent from the following detailed description of the application.

[0037] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Unless specifically indicated otherwise, the drawings are not necessarily to scale.

[0038] The application provides a mixed high-precision temperature control method based on normalization and switching bias PID, which realizes high-precision active temperature control of a spacecraft. The calculation output is directly the normalized output duty ratio of the heating loop, ranging from 0 to 1, and is not affected by the length change of the temperature control period. The proportional coefficient, integral coefficient and differential coefficient are calculated by normalization error calculation, and the value range is 0-1, which is the proportion of each. The parameters are intuitive and easy to adjust. The average desired duty ratio can be adjusted by setting the bias duty ratio parameter, different temperature control strategies can be realized, and the method has the advantages of strong universality.

[0039] As shown in Figure 1 , the mixed high-precision temperature control method based on normalization according to the application comprises the following steps:

[0040] (1) According to the pre-set lower limit T min of the temperature control threshold and the upper limit T max of the temperature control threshold, the temperature control target temperature T target =(T min +T max ) / 2 is calculated, the integral error sumErr=0 is initialized, and step (2) is entered;

[0041] (2) In the kth temperature control period, the actual temperature value of the controlled device is T(k), and step (3) is entered;

[0042] (3) The normalized temperature deviation e(k) = (T target -T(k)×2 / (T max -T min ) is calculated, and step (4) is entered;

[0043] (4) Calculate integral error sumErr = sumErr + e(k), and go to step (5);

[0044] (5) Calculate the desired output duty cycle DR(k) of the heating loop using the normalized temperature deviation e(k) and the integral error sumErr by a hybrid method of on-off plus bias PID, and go to step (6);

[0045] (6) If DR(k) > 100%, set DR(k) = 100%, and if DR(k) < 0, set DR(k) = 0, and control the output of the heating loop according to the duty cycle DR(k), and go to step (7);

[0046] (7) Wait for the next temperature control cycle, k = k + 1, and return to step (2).

[0047] Further, the target temperature T target is calculated autonomously by software.

[0048] Further, the duty cycle of the output of the heating loop in step (5) is calculated by a hybrid method of on-off plus bias PID, and the method is as follows: if e(k) ≥ 1, it indicates that the actual temperature value T(k) is less than or equal to the lower limit T min of the temperature control threshold, then the desired output duty cycle DR(k) of the heating loop is 100%, if e(k) ≤ -1, it indicates that the actual temperature value T(k) is greater than or equal to the upper limit T max of the temperature control threshold, then the desired output duty cycle DR(k) of the heating loop is 0%, and if -1 < e(k) < 1, the duty cycle is calculated by a bias PID method.

[0049] Further, the duty cycle calculated by the bias PID method is as follows:

[0050] DR(k) = bias + Kp × e(k) + Ki × sumErr + Kd × [e(k) - e(k-1)];

[0051] wherein Kp is a proportional coefficient, Ki is an integral coefficient, Kd is a differential coefficient, and bias is a bias duty cycle.

[0052] Further, the proportional coefficient Kp, the integral coefficient Ki, and the differential coefficient Kd have a value range of 0-1, and are the proportion of their respective errors, and can be modified by remote control.

[0053] Further, the bias duty cycle bias, whose value range is 0~1, can be adjusted according to the average expected duty cycle of the heating loop of the controlled object to set the bias duty cycle bias, so that the temperature control stability is higher. The modification can be remotely controlled, when bias is modified to 0, it is a normalized unbiased PID method; when bias=0.5, Kp=0.5, Ki=0, Kd=0, it is a normalized proportional temperature control method, that is, the duty cycle can be output in proportion in the temperature control interval; when Kd=0, it is a normalized PI method.

[0054] Further, the temperature control threshold lower limit T min and the temperature control threshold upper limit T max The modification can be remotely controlled, and the errors such as e(k-1) and sumErr are reinitialized after the threshold is modified.

[0055] Embodiments:

[0056] The application provides a normalized hybrid high-precision temperature control method, which first calculates the normalized temperature deviation between the actual temperature value and the temperature control target temperature, directly controls the average expected output duty cycle of the heating loop according to the bias, and controls the actual output duty cycle of the heating loop by using the normalized PID+switch control mode.

[0057] The temperature control threshold lower limit T min of the application, the temperature control threshold upper limit T max , the bias duty cycle bias, the proportional coefficient Kp, the integral coefficient Ki and the differential coefficient Kd can be stored in Flash / EEprom and RAM in the form of a table, and can be remotely controlled and modified, and the on-board parameter storage representation is shown in Table 1.

[0058] Table 1 on-board parameter storage representation example

[0059]

[0060] Experiments show that the temperature control stability of the temperature control algorithm is better than 0.03℃ / orbit.

[0061] The application is described in detail in combination with the specific embodiments and exemplary examples, but these descriptions cannot be understood as limitations of the application. Those skilled in the art understand that the technical solutions and embodiments of the application can be variously replaced, modified or improved without departing from the spirit and scope of the application, and these all fall within the scope of the application. The protection scope of the application is subject to the appended claims.

[0062] The contents not described in detail in the specification of the application are the known technology of those skilled in the art.

Claims

1. A hybrid high-precision temperature control method based on normalization, characterized in that, The method comprises the following steps: (1) obtaining a temperature control target temperature T target based on a pre-set temperature control threshold lower limit T min and a temperature control threshold upper limit T max . (2) collecting the actual temperature value T(k) of the controlled device in the kth temperature control cycle, k=1, 2, 3, …; (3) The normalized temperature deviation e(k) of the kth temperature control cycle is obtained according to the temperature control threshold lower limit T min , the temperature control threshold upper limit T max , the temperature control target temperature T target , and the actual temperature value T(k) of the controlled device. e(k) = (T target -T(k)) x 2 / (T max -T min ); (4) obtaining the integral error sumErr(k) of the kth temperature control cycle according to the normalized temperature deviation e(k) of the kth temperature control cycle and the integral error sumErr(k-1) of the previous k-1 temperature control cycles; (5) obtaining the expected output duty cycle DR(k) of the heating loop according to the normalized temperature deviation e(k) of the kth temperature control cycle and the integral error sumErr(k) of the kth temperature control cycle; (6) controlling the output duty cycle of the heating loop to be DR(k); (7) returning to step (2) in the k+1th temperature control cycle; In step (5), the method for obtaining the expected output duty cycle DR(k) of the heating loop according to the normalized temperature deviation e(k) of the kth temperature control cycle and the integral error sumErr(k) of the kth temperature control cycle is as follows: When e(k)≥1, DR(k)=100%; If e(k)≤-1, DR(k)=0%; If -1<e(k)<1, the duty cycle is calculated by using the PID method.

2. The normalized hybrid high-precision temperature control method according to claim 1, wherein, In step (1), T target = (T min + T max ) / 2.

3. The method according to claim 1, wherein, In step (4), sumErr(k)=sumErr(k-1)+e(k); The initial value of the integral error sumErr(0)=0.

4. The normalized hybrid high-precision temperature control method according to claim 1, wherein, If -1<e(k)<1, the duty cycle is calculated by using the bias PID method, specifically as follows: DR(k)=bias+Kp×e(k)+Ki×sumErr(k)+Kd×[e(k)-e(k-1)]; Wherein, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the differential coefficient, and bias is the bias duty cycle, which is used to adjust the temperature control stability.

5. The normalized hybrid high-precision temperature control method according to claim 4, characterized in that, The value range of Kp, Ki, Kd and bias is 0-1.

6. The normalized hybrid high-precision temperature control method according to claim 1, wherein, In step (6), if DR(k)>100%, let DR(k)=100%, if DR(k)<0, let DR(k)=0.

7. The normalized hybrid high-precision temperature control method according to claim 1, wherein, Step (5) is performed at the beginning of the kth temperature control cycle, and step (6) is performed in the kth temperature control cycle.

8. The normalized hybrid high-precision temperature control method according to claim 1, wherein, In step (1), the temperature control target temperature T target from the respective software according to a pre-set lower temperature control threshold T min and an upper temperature control threshold T max is autonomously calculated.

9. The normalized hybrid high-precision temperature control method according to claim 1, wherein, Temperature control threshold lower limit T min Temperature control threshold upper limit T max The values of the bias duty cycle bias, the proportional coefficient Kp, the integral coefficient Ki and the derivative coefficient Kd are stored in Flash / EEprom and in RAM in tabular form and are modified by remote control.

Images