Surge high-voltage closed-loop feedback automatic control system

Abstract

The utility model discloses a surge high-voltage closed-loop feedback automatic control system, and relates to the technical field of surge high-voltage automatic control systems. The circuit comprises a feedback network composed of an operational amplifier U1, a first resistor R1, a first capacitor C1, a second resistor R2 and a second capacitor C2. The circuit also comprises a third resistor R3, a fourth resistor R4, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5. The utility model has the advantages of few devices, symmetrical structure, beautiful circuit board layout, less device parameter differentiation, clear and simple circuit structure hierarchy and convenient maintenance and debugging, and can reduce the warehouse material number and improve the warehouse management efficiency; required Kp, Ki and Kd values can be easily obtained by changing parameter values of the resistors R1, R2, R3 and R4 and the capacitors C1, C2, C3 and C4. The circuit not only has timely and rapid proportional action, but also has residual error elimination capability with integral action and advanced control function with differential action.

Description

Technical Field

[0001] The utility model belongs to the technical field of surge high-voltage automatic control systems, in particular to a surge high-voltage closed-loop feedback automatic control system. Background Art

[0002] Closed-loop feedback control is an automatic control based on the feedback principle. It compares the deviation between system behavior (output) and expected behavior and eliminates the deviation to obtain the expected system performance. In closed-loop feedback control, there is both a forward signal path from input to output and a signal feedback path from output to input, which form a closed loop. Closed-loop feedback control consists of a controller, a controlled object and a feedback path.

[0003] For surge high voltage scenarios, the structure and parameters of the controlled object cannot be fully mastered at present. For example, the primary power supply voltage of the transformer is generated by a linear voltage regulator circuit composed of discrete devices, and the output power supply voltage cannot obtain an accurate and specific value. During the control process, the voltage fluctuates at any time, even if the ripple is very small, or when an accurate mathematical model cannot be obtained, other control theory technologies are difficult to adopt. The structure and parameters of the system controller must be determined by experience and on-site debugging. At this time, the PID control technology is most convenient. PID control is a control law formed by performing proportional, integral and differential operations on the deviation signal e(t). Usually, the hardware circuit implementation requires four operational amplifier circuits to generate proportional terms, integral terms, differential terms, etc., which are connected in parallel to generate a PID control circuit and a difference generation circuit and a subtraction circuit between the input signal and the feedback information. How to use one operational amplifier circuit to realize PID control and subtraction circuit has become a technical difficulty in hardware implementation; the leakage magnetic and magnetic saturation parameters of the step-up transformer are quantitative indicators that are not easy to obtain, and simple proportional control is the simplest control method; the output of its controller is proportional to the input error signal; when only proportional control is used, there is a steady-state error in the system output; therefore, this technical solution proposes a surge high-voltage closed-loop feedback automatic control system. Utility Model Content

[0004] The utility model provides a surge high-voltage closed-loop feedback automatic control system, the purpose of which is to use an operational amplifier circuit to realize a PID control circuit, which can reduce steady-state errors. At the same time, the circuit is simple, and an operational amplifier realizes four operation functions, namely, subtraction, proportion, integration and differentiation. It has the characteristics of high efficiency, high reliability and high cost performance, and is worthy of popularization and application. In summary, the problems in the background technology are solved.

[0005] In order to solve the above technical problems, the utility model is realized by the following technical solutions:

[0006] The utility model discloses a surge high-voltage closed-loop feedback automatic control system, comprising an operational amplifier U1, a first resistor R1, a first capacitor C1, a second resistor R2, and a second capacitor C2 to form a feedback network; the control system also comprises a third resistor R3, a fourth resistor R4, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5;

[0007] The first pin of the third resistor R3 is connected to the first pin of the third capacitor C3 and then connected to the input port Vin; the second pin of the third resistor R3, the second pin of the third capacitor C3 and the second pin of the fourth capacitor C4, a total of three pins, are connected to the third pin of the first operational amplifier U1, i.e., the non-inverting input terminal; the second pin of the fourth resistor R4 is connected to the first pin of the fourth capacitor C4; the first pin of the fourth resistor R4 is grounded GND;

[0008] The seventh pin of the operational amplifier U1 and the first pin of the fifth capacitor C5 are connected to the positive power supply VCC; the second pin of the fifth capacitor C5 is grounded GND; the fourth pin of the operational amplifier U1 is connected to the negative power supply GND;

[0009] The first pin of the first resistor R1 is connected to the first pin of the first capacitor C1 and then connected to the feedback signal terminal Vf; the second pin of the first resistor R1, the second pin of the first capacitor C1 and the first pin of the second capacitor C2 are connected to the second pin of the first operational amplifier U1, i.e., the inverting input terminal; the second pin of the second capacitor C2 is connected to the first pin of the second resistor R2; the second pin of the second resistor R2 is connected to the sixth pin of the first operational amplifier U1, i.e., the output terminal.

[0010] Furthermore, the operational amplifier U1 has a model of uA471.

[0011] Furthermore, the third resistor R3 has the same resistance value as the first resistor R1, the third capacitor C3 has the same capacitance value as the first capacitor C1; the fourth resistor R4 has the same resistance value as the second resistor R2; and the fourth capacitor C4 has the same capacitance value as the second capacitor C2.

[0012] Furthermore, the input port Vin is a set value, the feedback signal terminal Vf is an output value, and the control deviation e(t)=(Vin-Vf) is a difference between the set value and the output value.

[0013] Compared with the prior art, the utility model has the following beneficial effects:

[0014] (1) Compared with the prior art, the present invention has fewer components, a symmetrical structure, a beautiful circuit board layout, fewer component parameter distinctions, can reduce warehouse material numbers and improve warehouse management efficiency, has a clear and simple circuit structure, and is easy to repair and debug;

[0015] (2) The circuit debugging of this technical solution is relatively simple and easy to operate.

[0016] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a structural diagram of a surge high voltage closed-loop feedback automatic control system, namely, a PID circuit implementation of the utility model;

[0019] Figure 2 In a specific embodiment Figure 1 Equivalent circuit diagram of

[0020] Figure 3 It is a schematic diagram of the existing traditional PID circuit implementation;

[0021] Figure 4 This is a schematic diagram for the proportional circuit implementation;

[0022] Figure 5 This is a schematic diagram of the principle of PID control;

[0023] Figure 6 This is a schematic diagram of the surge generator. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] like Figure 5 As shown in the figure, it is a schematic diagram of the working principle of PID control. The actuator is a module circuit that generates surge high voltage, and the output is stabilized through the negative feedback circuit and the PID control circuit. In order to realize the PID control function, a single-stage operational amplifier circuit is used to realize all four automatic control adjustment functions including subtraction, proportion, integration and difference, such as Figure 1 As shown, a surge high voltage closed-loop feedback automatic control system of the technical solution is provided;

[0026] like Figure 4 As shown, it is a relatively simple single proportional regulation, which is the feedback regulation method used by the surge module before, that is, a relatively simple PID control method; see for details:

[0027] Reference: "Basics of Analog Electronic Technology" edited by Tong Shibai and Hua Chengying. 3rd edition. - Beijing: Higher Education Press, 2000, Figure 2 Excerpted from 7.2.1 Proportional Circuit; 7.2.2 Integral Circuit; 7.2.3 Differential Circuit Figure 3 Extracted from 7.2.1 Proportional Circuit;

[0028] like Figure 3 As shown, it is a traditional PID controller implementation circuit, which includes proportional, integral and differential control circuits, the three of which are connected in parallel and have many devices;

[0029] like Figure 6 As shown, it is a schematic diagram of the principle of the surge generator. The PID control output signal can control the supply voltage of the DC-AC converter to achieve the control of the surge output voltage, where Vi = e(t) = (Vin-Vf);

[0030] See also Figure 1 As shown, a surge high-voltage closed-loop feedback automatic control system of the utility model includes a feedback network composed of an operational amplifier U1, a first resistor R1, a first capacitor C1, a second resistor R2, and a second capacitor C2; the control system also includes a third resistor R3, a fourth resistor R4, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5;

[0031] The first pin of the third resistor R3 is connected to the first pin of the third capacitor C3 and then connected to the input port Vin; the second pin of the third resistor R3, the second pin of the third capacitor C3 and the second pin of the fourth capacitor C4, a total of three pins, are connected to the third pin of the first operational amplifier U1, i.e., the non-inverting input terminal; the second pin of the fourth resistor R4 is connected to the first pin of the fourth capacitor C4; the first pin of the fourth resistor R4 is grounded GND;

[0032] The seventh pin of the operational amplifier U1 and the first pin of the fifth capacitor C5 are connected to the positive power supply VCC; the second pin of the fifth capacitor C5 is grounded GND; the fourth pin of the operational amplifier U1 is connected to the negative power supply GND;

[0033] The first pin of the first resistor R1 is connected to the first pin of the first capacitor C1 and then connected to the feedback signal terminal Vf; the second pin of the first resistor R1, the second pin of the first capacitor C1 and the first pin of the second capacitor C2 are connected to the second pin of the first operational amplifier U1, i.e., the inverting input terminal; the second pin of the second capacitor C2 is connected to the first pin of the second resistor R2; the second pin of the second resistor R2 is connected to the sixth pin of the first operational amplifier U1, i.e., the output terminal;

[0034] The input port Vin is the set value, the feedback signal terminal Vf is the output value, and the control deviation e(t)=(Vin-Vf) is the difference between the set value and the output value.

[0035] The model of the operational amplifier U1 is uA471; the third resistor R3 has the same resistance value as the first resistor R1, the third capacitor C3 has the same capacitance value as the first capacitor C1; the fourth resistor R4 has the same resistance value as the second resistor R2; the fourth capacitor C4 has the same capacitance value as the second capacitor C2.

[0036] like Figure 2 As shown, Figure 1 The equivalent circuit of Figure 2 It is a classic subtraction circuit, Vin-Vf=Z2 / Z1, combined with Figure 1 , the transfer function is calculated as follows:

[0037] VOUT(S) / E(S)=Z2(S) / Z1(S)=R2 / R1+C1 / C2+SR2C1+1 / (SR1C2)

[0038] The proportional term is: R2 / R1+C1 / C2=R4 / R3+C3 / C4

[0039] The integral term is: 1 / (SR1C2) = 1 / (SR3C4)

[0040] The differential term is: SR2C1 = SR4C3

[0041] Where: E(S) = (Vin(S) - Vf(S))

[0042] The key components are described as follows:

[0043] The integral capacitors are C2 and C4; the integral resistors are R1 and R3. The differential capacitors are C1 and C3; the differential resistors are R2 and R4; the proportional resistors are R1, R2, R3, R4; the proportional capacitors are C1, C2, C3, C4; the operational amplifier is U1, model uA471

[0044] The key device parameters are described as follows:

[0045] Parameter tuning to find the best, from small to large order; first the proportion, then the integral, and finally the differential;

[0046] The specific values ​​of P, I, and D parameters in the regulation system are determined according to the characteristics of the actual execution components. Usually: P = 20-60%, T = 180-600s, D = 3-180s; the formula is as follows

[0047]

[0048] This formula: Reference: "PID Controller Parameter Tuning and Implementation" by Huang Yourui and Qu Liguo, 1st edition. - Beijing: Science Press, 2010, formula extracted to formula (1.1) of 1.3;

[0049] The working principle of the utility model is:

[0050] The basic theory of PID is introduced as follows:

[0051] Today's closed-loop automatic control technology is based on the concept of feedback to reduce uncertainty. The elements of feedback theory include three parts: measurement, comparison and execution. The key to measurement is the actual value of the controlled variable, which is compared with the expected value, and this deviation is used to correct the response of the system and perform regulatory control. In engineering practice, the most widely used regulator control law is proportional, integral, and differential control, referred to as PID control, also known as PID regulation.

[0052] PID controller (proportional-integral-derivative controller) such as Figure 5 As shown. The basis of PID control is proportional control; integral control can eliminate steady-state errors, but may increase overshoot; differential control can speed up the response speed of large inertia systems and reduce overshoot trends. The actuator is generally a nonlinear network, and its transfer function is difficult to express analytically. This device, the surge generator, is an actuator. Its function is to output an analog value through the PID controller according to the set value Vin after comparing the difference with the feedback of the surge high voltage. The analog value controls the size of the power supply voltage of the DC-AC converter. The size of the power supply voltage can indirectly control the size of the output AC effective value of the DC-AC converter. The output AC signal of the DC-AC converter can obtain the surge pulse voltage after rectification.

[0053] The most ideal control circuit is the proportional-integral-differential control circuit. Figure 1 The circuit shown has the advantages of three aspects: it has the promptness of proportional action, the ability to eliminate residual errors of integral action, and the advanced control function of differential action.

[0054] When the deviation step occurs, the differential immediately acts in a large range to suppress the deviation jump; the proportional action also plays a role in eliminating the deviation, reducing the deviation amplitude. Since the proportional action is a lasting and main control law, it can make the system more stable; and the integral action slowly overcomes the residual error. As long as the control parameters of the three actions are properly selected, the advantages of the three control laws can be fully utilized to obtain a more ideal control effect.

[0055] PID control is proportional-integral-differential control (Proportional-Integral-Differential) input: control deviation e(t) = r(t)-y(t); output: a linear combination of the proportional (P), integral (I) and differential (D) of the deviation:

[0056] Where: KP is the proportional coefficient; TI is the integral time constant; TD is the differential time constant;

[0057] The PID controller consists of a proportional unit (P), an integral unit (I) and a differential unit (D). Its basic principle is relatively simple. The basic PID control law can be described as (transfer function):

[0058]

[0059] From the above theoretical introduction and the PID circuit of this technical solution, it is easy to know

[0060] Kp=R2 / R1+C1 / C2

[0061] Ki=1 / (R1C2)

[0062] Kd=R2C1

[0063] Analysis of the impact of PID parameters on system performance:

[0064] The influence of proportional coefficient Kp on system performance:

[0065] (1) Impact on the dynamic performance of the system: When Kp increases, the system response speed will increase. When Kp is too large, the number of system oscillations increases and the adjustment time is prolonged. If Kp is too small, the system response speed will be slow. Kp should be selected so that the output response produces a 4:1 attenuation process.

[0066] (2) Impact on the steady-state performance of the system: Under the premise of system stability, increasing Kp can reduce the steady-state error, but it cannot eliminate the steady-state error. Therefore, the setting of Kp is mainly based on the dynamic performance of the system.

[0067] The impact of integral time Ti on system performance: Integral control usually works together with proportional control or proportional differential control to form PI control or PID control.

[0068] (1) Impact on the dynamic performance of the system: Integral control usually affects the stability of the system. If TI is too small, the system may be unstable and oscillate more frequently; if TI is too large, the impact on the system will be weakened; when TI is more suitable, the transient characteristics of the system are more ideal.

[0069] (2) Impact on the steady-state performance of the system: Integral control helps to eliminate the steady-state error of the system and improve the control accuracy of the system. However, if TI is too large and the integral effect is too weak, the residual error cannot be reduced.

[0070] The influence of differential time TD on system performance: Differential control usually works together with proportional control or proportional integral control to form PD control or PID control.

[0071] (1) Impact on the dynamic performance of the system: The increase of the differential time TD, that is, the increase of the differential action, can improve the dynamic characteristics of the system, such as reducing overshoot and shortening the adjustment time. Properly increasing the proportional control can reduce the steady-state error and improve the control accuracy. However, a TD value that is too large or too small will be counterproductive. In addition, the differential action may amplify the noise of the system and reduce the anti-interference ability of the system.

[0072] (2) Impact on the steady-state performance of the system: The addition of the differential link can control the deviation change trend at the moment when the error appears or changes. It introduces an early correction effect, which helps to increase the stability of the system.

[0073] The parameters of the PID controller must be considered according to the specific requirements of the engineering problem; in industrial process control, it is usually necessary to ensure that the closed-loop system is stable, the changes in the given quantity can be tracked quickly, and the overshoot is small. The output should be able to remain near the given value under different interferences, the control amount should be as small as possible, and the control should remain stable when the system and environmental parameters change. Generally speaking, it is difficult to meet these requirements at the same time. It is necessary to meet the main performance indicators according to the specific conditions of the system while taking into account other requirements.

[0074] The required Kp, Ki, and Kd values ​​can be easily obtained by changing the parameter values ​​of resistors R1, R2, R3, R4 and capacitors C1, C2, C3, and C4. The circuit debugging is relatively simple and easy to operate.

[0075] The preferred embodiments of the utility model disclosed above are only used to help explain the utility model. The preferred embodiments do not describe all the details in detail, nor do they limit the utility model to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the utility model, so that technicians in the relevant technical field can well understand and use the utility model. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A surge high voltage closed-loop feedback automatic control system, characterized in that: A feedback network including an operational amplifier U1, a first resistor R1, a first capacitor C1, a second resistor R2, and a second capacitor C2; the control system also includes a third resistor R3, a fourth resistor R4, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5; The first pin of the third resistor R3 is connected to the first pin of the third capacitor C3 and then connected to the input port Vin; The second pin of the third resistor R3, the second pin of the third capacitor C3 and the second pin of the fourth capacitor C4, a total of three pins, are connected together to the third pin, i.e., the non-inverting input terminal, of the first operational amplifier U1; the second pin of the fourth resistor R4 and the first pin of the fourth capacitor C4 are connected together; the first pin of the fourth resistor R4 is grounded GND; The seventh pin of the operational amplifier U1 and the first pin of the fifth capacitor C5 are connected to the positive power supply VCC; the second pin of the fifth capacitor C5 is grounded GND; the fourth pin of the operational amplifier U1 is connected to the negative power supply GND; The first pin of the first resistor R1 is connected to the first pin of the first capacitor C1 and then connected to the feedback signal terminal Vf; the second pin of the first resistor R1, the second pin of the first capacitor C1 and the first pin of the second capacitor C2 are connected to the second pin of the first operational amplifier U1, i.e., the inverting input terminal; the second pin of the second capacitor C2 is connected to the first pin of the second resistor R2; the second pin of the second resistor R2 is connected to the sixth pin of the first operational amplifier U1, i.e., the output terminal.

2. A surge high voltage closed-loop feedback automatic control system according to claim 1, characterized in that: The model of the operational amplifier U1 is uA471.

3. A surge high voltage closed-loop feedback automatic control system according to claim 1, characterized in that: The third resistor R3 has the same resistance value as the first resistor R1, the third capacitor C3 has the same capacitance value as the first capacitor C1; the fourth resistor R4 has the same resistance value as the second resistor R2; the fourth capacitor C4 has the same capacitance value as the second capacitor C2.

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