Method and system for constructing overvoltage protection circuit of temperature drift resistant thyristor

Abstract

The invention discloses a temperature drift resistant thyristor overvoltage protection circuit construction method and system, and relates to the technical field of power electronics, and the method comprises the steps: collecting the voltage between an anode and a cathode of a thyristor, dividing the voltage, and connecting the divided voltage to the in-phase input end of a voltage comparator, the operational amplifier outputs a forward-saturated or reverse-saturated voltage signal after passing through the voltage comparator; the output of the voltage comparator is subjected to voltage division through a resistor; the voltage is connected to a current amplification circuit composed of an in-phase proportional amplifier and an OTL complementary symmetric amplification circuit; the output end of the current amplification circuit is connected with a current-limiting resistor through a voltage-regulator tube, a diode and then connected to a gate pole of the thyristor, when the thyristor bears forward overvoltage, the voltage-regulator tube breaks down, the gate pole of the thyristor is triggered to conduct the thyristor, and the overvoltage protection function of the thyristor is achieved; according to the thyristor overvoltage protection circuit, the overvoltage protection speed and precision can be improved, the temperature drift of the triode amplification circuit is inhibited, and the thyristor overvoltage protection function with high sensitivity and temperature drift resistance is realized.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a method and system for constructing a temperature-drift-resistant thyristor overvoltage protection circuit. Background Art

[0002] Since their invention in the late 1950s, thyristors have rapidly become a key component in power electronics due to their ability to handle higher power levels. However, thyristors are susceptible to overvoltage during operation, primarily due to transient fluctuations in the power grid, circuit switching, kickback currents from inductive loads, and the startup and shutdown of equipment. Overvoltage can not only damage the thyristor itself but can also trigger a chain reaction that harms the entire power system. Therefore, protecting thyristors from overvoltage has become a significant technical challenge to improve the stability and reliability of power electronics systems.

[0003] At present, thyristors still have a place in high voltage and high current applications, such as HVDC and high voltage SVC. In applications, due to the inherent fragility of power electronic devices, simply increasing the design margin of the device to increase the reliability of the entire equipment is an uneconomical and unnecessary measure. The general practice is to adopt various protection measures to fully utilize the capacity of the device. Break Over Diode (BOD) is an overvoltage protection device for thyristors. Due to its fast speed, as long as the protection circuit design parameters are reasonably selected, thyristors can be reliably protected at the component level. With the invention and continuous improvement of thyristor overvoltage protection circuits, BOD is often used in thyristor overvoltage protection. High-voltage breakover diode BOD is a key component in thyristor overvoltage protection circuits. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: for devices such as turn diodes that have no domestic alternative products, how to research new thyristor overvoltage protection circuits to achieve functional replacement and ultimately achieve domestic replacement of thyristor protection circuits.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit, comprising:

[0008] The voltage between the anode and cathode of the thyristor is collected and connected to the non-inverting input of the voltage comparator after voltage division. After passing through the voltage comparator, the op amp outputs a forward saturation or reverse saturation voltage signal;

[0009] Divide the output of the voltage comparator by resistors;

[0010] The divided voltage is connected to a current amplification circuit composed of a common-mode proportional amplifier and an OTL complementary symmetrical amplifier circuit; the common-mode proportional amplifier outputs an amplified voltage signal, and the OTL complementary symmetrical amplifier circuit is connected between the output terminal and the feedback terminal of the common-mode proportional amplifier to amplify the output current of the operational amplifier to the current required to turn on the thyristor gate;

[0011] The output end of the current amplifier circuit is connected to the thyristor gate through a voltage regulator, a diode and a current limiting resistor. When the thyristor is subjected to a forward overvoltage, the voltage regulator breaks down, the thyristor gate is triggered and the thyristor is turned on, thus realizing thyristor overvoltage protection.

[0012] As a preferred solution for the method of constructing a temperature-drift-resistant thyristor overvoltage protection circuit, wherein:

[0013] The anti-temperature drift thyristor overvoltage protection circuit consists of a voltage comparator, a non-inverting proportional amplifier, a diode, a voltage regulator, a transistor, a resistor and a capacitor. Two integrated operational amplifier chips are used in the voltage comparator and the non-inverting proportional amplifier respectively; the resistors include: voltage divider resistors R1, R2, R3, R4, R 12 and R 13 , current limiting resistors R5, R6, R7, R8, R9, R 10 、R 14 、R 15 , feedback resistor R F , loop discharge resistance R 11 The capacitor is C; the diodes are D1, D2 and D3; the voltage regulators include VD1 and VD2; the transistors include NPN tube T1 and PNP tube T2; the thyristor is SCR;

[0014] The diode D1 is connected between the current limiting resistor R7 and the output of the in-phase proportional amplifier; the diode D2 is connected between the current limiting resistor R8 and the in-phase proportional amplifier; the voltage regulator VD1 is connected between the diode D3 and the emitters of the transistors T1 and T2; the diode D3 is connected between the voltage regulator VD1 and the current limiting resistor R9; the voltage regulator VD2 is connected between the current limiting resistor R 15 In parallel, the current limiting resistor R9 is connected between the diode D3 and the gate of the thyristor SCR; the loop discharge resistor R 11 It is connected in series with the capacitor C and then in parallel with the thyristor SCR; the power supply for the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit is taken from both ends of the thyristor, and after passing through the voltage stabilizing circuit, a stable DC voltage is output to power the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit.

[0015] As a preferred solution for the method of constructing a temperature-drift-resistant thyristor overvoltage protection circuit, wherein:

[0016] The method of outputting a stable DC voltage after the voltage stabilizing circuit to power the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit includes:

[0017] Select the voltage regulator VD2 according to the following formula:

[0018]

[0019] Among them U Z is the voltage across the Zener diode, U CC R 15 The voltage across the terminals, I ZM I is the maximum current allowed to pass through the Zener diode. OM is the current flowing through the current limiting resistor R 15 The maximum current, U1 is the voltage divider resistor R 13 The voltage across both ends is determined by the following formula to select the voltage divider resistor R 12 With R 13 Resistance value:

[0020] U1=(2~3)U CC

[0021] Select the current limiting resistor R according to the following formula 14 With R 15 Resistance value:

[0022] IZM=(1.5~3)IOM.

[0023] As a preferred solution for the method of constructing a temperature-drift-resistant thyristor overvoltage protection circuit, wherein:

[0024] The output forward saturation or reverse saturation voltage signal includes:

[0025] Assume that the action voltage of the thyristor overvoltage protection circuit is U F , determine the voltage divider resistors R1, R2 and the reference voltage U input to the inverting input of the voltage comparator according to the following formula: ref :

[0026] U ref =U F ×R2 / (R1+R2)

[0027] The voltage after being divided by the voltage divider resistors R1 and R2 is connected to the non-inverting input terminal of the voltage comparator; when the forward voltage across the thyristor is less than the action voltage U of the protection circuit FWhen the voltage at the non-inverting input of the voltage comparator is less than the voltage at the inverting input, the voltage comparator outputs a reverse saturation voltage signal; when the forward voltage across the thyristor is greater than or equal to the action voltage U of the protection circuit F When , the voltage at the non-inverting input of the voltage comparator is greater than the voltage at the inverting input, and the voltage comparator outputs a forward saturated voltage signal.

[0028] As a preferred solution for the method of constructing a temperature-drift-resistant thyristor overvoltage protection circuit, wherein:

[0029] The step of dividing the output terminal of the voltage comparator by a resistor comprises:

[0030] Determine the values ​​of the voltage divider resistors R3 and R4 according to the following formula to ensure that the non-inverting proportional amplifier operates normally within the supply voltage range of the op amp:

[0031] U i2 =U o1 ×R4 / (R3+R4)

[0032] Among them U i2 is the voltage at the input of the non-inverting proportional amplifier, U o1 is the output voltage of the voltage comparator.

[0033] As a preferred solution for the method of constructing a temperature-drift-resistant thyristor overvoltage protection circuit, wherein:

[0034] The step of amplifying the output current of the operational amplifier to a current required for turning on the thyristor gate includes:

[0035] Set the current limiting resistor R5 = R6 / / R F After selecting the amplification factor of the in-phase proportional amplifier, select R5, R6 and feedback resistor R according to the amplification factor formula of the in-phase proportional amplifier. F The resistance value of the in-phase proportional amplifier is expressed as follows:

[0036] U o3 / U i2 =(1+R F / R6)

[0037] Among them U o3 is the output voltage of the non-inverting proportional amplifier, U i2 is the voltage at the input of the non-inverting proportional amplifier.

[0038] As a preferred solution for the method of constructing a temperature-drift-resistant thyristor overvoltage protection circuit, wherein:

[0039] The step of connecting the output end of the current amplifying circuit to the gate of the thyristor via a voltage regulator tube, a diode and a current limiting resistor comprises:

[0040] When the forward voltage across the thyristor is greater than the protection voltage action value, the voltage regulator value U is selected. Z The resistance value of the current limiting resistor R9 is as follows:

[0041] U o3 =U Z +U D3 +R9×I G +U G

[0042] Among them U Z is the voltage regulation value of the voltage regulator tube, I G is the current value of the thyristor gate branch, U G is the gate voltage of the thyristor. Both must be within the range specified in the thyristor data sheet that enables the thyristor to be stably turned on.

[0043] In a second aspect, an embodiment of the present invention provides a system for constructing a temperature-drift-resistant thyristor overvoltage protection circuit, comprising:

[0044] The acquisition module is used to collect the voltage between the anode and cathode of the thyristor, and connect it to the non-inverting input terminal of the voltage comparator after voltage division. After passing through the voltage comparator, the operational amplifier outputs the forward saturation or reverse saturation voltage signal;

[0045] A voltage divider module is used to divide the output of the voltage comparator through a resistor;

[0046] The current drive amplifier module is used to connect the divided voltage to the current amplifier circuit composed of a common-mode proportional amplifier and an OTL complementary symmetrical amplifier circuit. The common-mode proportional amplifier outputs an amplified voltage signal, and the OTL complementary symmetrical amplifier circuit is connected between the output terminal and the feedback terminal of the common-mode proportional amplifier to amplify the output current of the operational amplifier to the current required to turn on the thyristor gate.

[0047] The thyristor overvoltage protection module is used to connect the output end of the current amplifier circuit to the thyristor gate through a voltage regulator, a diode and a current limiting resistor. When the thyristor is subjected to a forward overvoltage, the voltage regulator breaks down, the thyristor gate is triggered, and the thyristor is turned on, thereby realizing thyristor overvoltage protection.

[0048] In a third aspect, an embodiment of the present invention provides a computing device, including:

[0049] memory and processor;

[0050] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the one or more programs are executed by the one or more processors, the one or more processors implement the method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit as described in any embodiment of the present invention.

[0051] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit.

[0052] The beneficial effects of the present invention are as follows: the present invention is designed based on an integrated operational amplifier, which can improve the speed and accuracy of overvoltage protection. At the same time, a diode is connected to the OTL circuit to suppress the temperature drift of the transistor amplifier circuit, thereby realizing a high-sensitivity and temperature-drift-resistant thyristor overvoltage protection function; the present invention proposes a thyristor overvoltage protection circuit without BOD, which is used to protect the thyristor when it is subjected to a forward overvoltage, preventing the thyristor from being damaged when subjected to the forward overvoltage, and has good temperature-drift resistance, weakening the influence of temperature on the circuit protection action characteristics, and providing protection for the safe and stable operation of the thyristor and the entire circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0054] Figure 1 This is an overall flow chart of the method for constructing an anti-temperature drift thyristor overvoltage protection circuit according to the first embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of a thyristor overvoltage protection circuit according to a method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to a first embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of the working circuit of the thyristor overvoltage protection circuit during forward overvoltage in the method for constructing a temperature drift resistant thyristor overvoltage protection circuit according to the first embodiment of the present invention;

[0057] Figure 4 This is a simulation result of a thyristor being subjected to a forward step voltage in a simulation example of a method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to a second embodiment of the present invention;

[0058] Figure 5 This is a simulation result of the thyristor being subjected to a forward linear rising voltage in a simulation example of the method for constructing a temperature drift thyristor overvoltage protection circuit according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0059] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0060] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0061] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0062] Example 1

[0063] Reference Figure 1-Figure 3 , which is the first embodiment of the present invention, provides a method for constructing an anti-temperature drift thyristor overvoltage protection circuit, comprising:

[0064] S1: collects the voltage between the anode and cathode of the thyristor, divides it and connects it to the non-inverting input of the voltage comparator. After passing through the voltage comparator, the op amp outputs a forward saturation or reverse saturation voltage signal.

[0065] In the embodiments of this application, Figure 2 As shown in the figure, the temperature drift thyristor overvoltage protection circuit is composed of a voltage comparator, a non-inverting proportional amplifier, a diode, a voltage regulator, a transistor, a resistor and a capacitor. Two integrated operational amplifier chips are used in the voltage comparator and the non-inverting proportional amplifier respectively; the resistors include: voltage divider resistors R1, R2, R3, R4, R 12 and R 13 , current limiting resistors R5, R6, R7, R8, R9, R 10 、R 14 、R 15 , feedback resistor R F , loop discharge resistance R 11 The capacitor is C; the diodes are D1, D2 and D3; the voltage regulators include VD1 and VD2; the transistors include NPN tube T1 and PNP tube T2; the thyristor is SCR;

[0066] The diode D1 is connected between the current limiting resistor R7 and the output of the in-phase proportional amplifier; the diode D2 is connected between the current limiting resistor R8 and the in-phase proportional amplifier; the voltage regulator VD1 is connected between the diode D3 and the emitters of the transistors T1 and T2; the diode D3 is connected between the voltage regulator VD1 and the current limiting resistor R9; the voltage regulator VD2 is connected between the current limiting resistor R 15 In parallel, the current limiting resistor R9 is connected between the diode D3 and the gate of the thyristor SCR; the loop discharge resistor R 11 It is connected in series with the capacitor C and then in parallel with the thyristor SCR; the power supply for the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit is taken from both ends of the thyristor, and after passing through the voltage stabilizing circuit, a stable DC voltage is output to power the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit.

[0067] After the voltage stabilization circuit, a stable DC voltage is output to power the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit.

[0068] Select the voltage regulator VD2 according to the following formula:

[0069]

[0070] Among them U Z is the voltage across the Zener diode, U CC R 15 The voltage across the terminals, I ZM I is the maximum current allowed to pass through the Zener diode. OM is the current flowing through the current limiting resistor R 15 The maximum current, U1 is the voltage divider resistor R 13 The voltage across both ends is determined by the following formula to select the voltage divider resistor R 12 With R 13 Resistance value:

[0071] U1=(2~3)U CC

[0072] Select the current limiting resistor R according to the following formula 14 With R 15 Resistance value:

[0073] IZM=(1.5~3)IOM.

[0074] The output voltage signals of forward saturation or reverse saturation include:

[0075] Assume that the action voltage of the thyristor overvoltage protection circuit is U F , determine the voltage divider resistors R1, R2 and the reference voltage U input to the inverting input of the voltage comparator according to the following formula: ref :

[0076] Uref =U F ×R2 / (R1+R2)

[0077] The voltage after being divided by the voltage divider resistors R1 and R2 is connected to the non-inverting input terminal of the voltage comparator; when the forward voltage across the thyristor is less than the action voltage U of the protection circuit F When the voltage at the non-inverting input of the voltage comparator is less than the voltage at the inverting input, the voltage comparator outputs a reverse saturation voltage signal; when the forward voltage across the thyristor is greater than or equal to the action voltage U of the protection circuit F When , the voltage at the non-inverting input of the voltage comparator is greater than the voltage at the inverting input, and the voltage comparator outputs a forward saturated voltage signal.

[0078] S2: divide the output of the voltage comparator through resistors;

[0079] In the embodiment of the present application, dividing the output terminal of the voltage comparator by a resistor includes:

[0080] Determine the values ​​of the voltage divider resistors R3 and R4 according to the following formula to ensure that the non-inverting proportional amplifier operates normally within the supply voltage range of the op amp:

[0081] U i2 =U o1 ×R4 / (R3+R4)

[0082] Among them U i2 is the voltage at the input of the non-inverting proportional amplifier, U o1 is the output voltage of the voltage comparator.

[0083] It should be noted that U o1 is the output voltage of the voltage comparator. When the thyristor overvoltage protection circuit is in action, it is the forward saturation voltage of the integrated operational amplifier. When the thyristor protection circuit is not in action, since the circuit is powered by a single power supply, the reverse power supply terminal of the integrated operational amplifier is grounded. o1 ≈0.

[0084] S3: The divided voltage is connected to a current amplification circuit composed of a common-mode proportional amplifier and an OTL complementary symmetrical amplifier circuit; the common-mode proportional amplifier outputs an amplified voltage signal, and the OTL complementary symmetrical amplifier circuit is connected between the output and feedback terminals of the common-mode proportional amplifier to amplify the output current of the op amp to the current required to turn on the thyristor gate;

[0085] In the embodiment of the present application, amplifying the output current of the operational amplifier to the current required for turning on the thyristor gate includes:

[0086] Set the current limiting resistor R5 = R6 / / R FAfter selecting the amplification factor of the in-phase proportional amplifier, select R5, R6 and feedback resistor R according to the amplification factor formula of the in-phase proportional amplifier. F The resistance value of the in-phase proportional amplifier is expressed as follows:

[0087] U o3 / U i2 =(1+R F / R6)

[0088] Among them U o3 is the output voltage of the non-inverting proportional amplifier, U i2 is the voltage at the input of the non-inverting proportional amplifier.

[0089] It should be noted that when the forward voltage across the thyristor is greater than the protection voltage action value, U o1 Always the forward saturation voltage, U o3 is also basically unchanged, then according to the formula U o3 =U Z +U D3 +R9×I G +U G , you can select the voltage regulation value U of the voltage regulator tube Z and the resistance of the current limiting resistor R9, where U Z is the voltage regulation value of the voltage regulator tube, I G is the current value of the thyristor gate branch, U G is the gate voltage of the thyristor, and both must be within the range specified in the thyristor data sheet that allows the thyristor to be stably turned on. At the same time, connecting a diode D3 in series after the voltage regulator VD1 can greatly reduce the effect of temperature on the voltage regulator VD1 and diode D3 when a voltage regulator with a voltage regulation value higher than 6V is selected, thereby making the thyristor overvoltage protection circuit have good temperature characteristics.

[0090] It should also be noted that according to the thyristor data sheet, the current signal output by the integrated operational amplifier cannot reach the gate current required to turn on the thyristor. Therefore, it is necessary to connect an OTL complementary symmetrical amplifier circuit after the integrated operational amplifier of the in-phase proportional amplifier circuit to amplify the current. When the thyristor is subjected to a forward overvoltage, the protection circuit is triggered, and transistor T1 operates in the amplification region with an amplification factor of β1; transistor T2 is in a partially conductive state, and diodes D1 and D2 play a role in eliminating crossover distortion, so that transistors T1 and T2 are both in a partially conductive state in the static state, U o2 ≈U o3 , where U o2 is the output voltage of the integrated operational amplifier in the non-inverting proportional amplifier, U o3is the output voltage of the non-inverting proportional amplifier. At the same time, the emitter junction of diode D1 and transistor T1, and the emitter junction of diode D2 and transistor T2 can be approximately regarded as a structure of two diodes in parallel, which greatly weakens the influence of temperature on diodes D1 and D2, and transistors T1 and T2.

[0091] S4: The output end of the current amplifier circuit is connected to the thyristor gate through a voltage regulator, a diode and a current limiting resistor. When the thyristor is subjected to a forward overvoltage, the voltage regulator breaks down, the thyristor gate is triggered, and the thyristor is turned on, thus realizing the thyristor overvoltage protection.

[0092] In an embodiment of the present application, connecting the output end of the current amplifier circuit to the gate of the thyristor via a voltage regulator, a diode, and a current limiting resistor includes:

[0093] When the forward voltage across the thyristor is greater than the protection voltage action value, the voltage regulator value U is selected. Z The resistance value of the current limiting resistor R9 is as follows:

[0094] U o3 =U Z +U D3 +R9×I G +U G

[0095] Among them U Z is the voltage regulation value of the voltage regulator tube, I G is the current value of the thyristor gate branch, U G is the gate voltage of the thyristor. Both must be within the range specified in the thyristor data sheet that enables the thyristor to be stably turned on.

[0096] It should be noted that the circuit proposed in the present invention does not contain BOD devices, and only uses resistors, diodes, transistors, voltage regulators and integrated operational amplifiers. It can meet the high-voltage operating conditions of thyristors. A new thyristor overvoltage protection circuit is studied, which realizes the domestic substitution of thyristor protection circuits, makes up for the shortcomings of domestic devices, and enables domestic devices to meet the needs of power applications. It is of great significance.

[0097] The thyristor overvoltage protection circuit proposed in the present invention utilizes the fast response advantages of a high-speed comparator and an operational amplifier circuit to achieve reliable triggering at the instant the forward voltage across the thyristor exceeds a set protection threshold. The thyristor gate branch voltage regulator is broken down, and under the action of a current-limiting resistor, the current in the thyristor gate branch and the gate voltage are both within the thyristor reliable conduction range specified in the thyristor data sheet. When the forward voltage across the thyristor does not exceed the set protection threshold, the thyristor gate branch voltage regulator does not break down, and the current in the thyristor gate branch and the gate voltage are both within the thyristor guaranteed non-conduction range specified in the thyristor data sheet, effectively preventing false triggering of the protection circuit.

[0098] In the thyristor overvoltage protection circuit proposed by the present invention, the diode D1 and the emitter junction of the transistor T1, as well as the emitter junction of the diode D2 and the transistor T2, can be approximately regarded as a structure in which two diodes are connected in parallel, thereby greatly reducing the influence of temperature on the diodes D1 and D2, and the transistors T1 and T2. In addition, a circuit structure in which the diode D3 is connected in series after the voltage regulator tube VD1 is adopted. This can greatly reduce the influence of temperature on the voltage regulator tube VD1 and the diode D3 when a voltage regulator tube with a regulated voltage value higher than 6V is selected, thereby ensuring that the thyristor overvoltage protection circuit has good temperature characteristics.

[0099] The above is a schematic diagram of the method for constructing a temperature-drift thyristor overvoltage protection circuit according to this embodiment. It should be noted that the technical solution of the system for constructing a temperature-drift thyristor overvoltage protection circuit and the technical solution of the method for constructing a temperature-drift thyristor overvoltage protection circuit are based on the same concept. For details not described in detail in the technical solution of the system for constructing a temperature-drift thyristor overvoltage protection circuit according to this embodiment, please refer to the description of the technical solution of the method for constructing a temperature-drift thyristor overvoltage protection circuit.

[0100] In this embodiment, the system for constructing a temperature-drift-resistant thyristor overvoltage protection circuit includes:

[0101] The acquisition module is used to collect the voltage between the anode and cathode of the thyristor, and connect it to the non-inverting input terminal of the voltage comparator after voltage division. After passing through the voltage comparator, the operational amplifier outputs the forward saturation or reverse saturation voltage signal;

[0102] A voltage divider module is used to divide the output of the voltage comparator through a resistor;

[0103] The current drive amplifier module is used to connect the divided voltage to the current amplifier circuit composed of a common-mode proportional amplifier and an OTL complementary symmetrical amplifier circuit. The common-mode proportional amplifier outputs an amplified voltage signal, and the OTL complementary symmetrical amplifier circuit is connected between the output terminal and the feedback terminal of the common-mode proportional amplifier to amplify the output current of the operational amplifier to the current required to turn on the thyristor gate.

[0104] The thyristor overvoltage protection module is used to connect the output end of the current amplifier circuit to the thyristor gate through a voltage regulator, a diode and a current limiting resistor. When the thyristor is subjected to a forward overvoltage, the voltage regulator breaks down, the thyristor gate is triggered, and the thyristor is turned on, thereby realizing thyristor overvoltage protection.

[0105] This embodiment further provides a computing device applicable to the method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit, including:

[0106] Memory and processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the method for constructing an anti-temperature drift thyristor overvoltage protection circuit as proposed in the above embodiment.

[0107] This embodiment further provides a storage medium storing a computer program, which, when executed by a processor, implements the method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit as proposed in the above embodiment.

[0108] The storage medium proposed in this embodiment and the method for constructing an anti-temperature drift thyristor overvoltage protection circuit proposed in the above embodiment belong to the same inventive concept. For technical details not described in detail in this embodiment, please refer to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0109] Example 2

[0110] Reference Figure 4-Figure 5 , is an embodiment of the present invention, which provides a method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through simulation experiments.

[0111] In this simulation example, the circuit parameters are selected as follows:

[0112] ① Selection of R1 and R2 parameters: When the maximum forward withstand voltage of a certain type of thyristor is known and the protection voltage value U is determined F Then, according to the formula U ref =U F × R2 / (R1+R2) to determine the voltage divider resistors R1, R2 and the reference voltage U input to the inverting input of the voltage comparator ref This method selects the values ​​of R1 and R2 based on the consideration that when the thyristor reaches the maximum withstand voltage, R1 and R2 must work normally without overpower or burnt. In this example, the thyristor model selected is st1200c12k, which has a maximum forward withstand voltage of 1200V and a protection voltage of 800V. The selected R1 is 10.6kΩ, R2 is 100Ω, and the reference voltage U ref is 7.47V.

[0113] ② Selection of integrated operational amplifier model: Integrated operational amplifiers are used in both voltage comparators and non-inverting proportional amplifiers. Since the thyristor overvoltage protection circuit requires the circuit to have high precision and relatively good temperature stability, the AD826 chip is selected in this example. In terms of precision, the AD826 has extremely low input bias current and drift, which is suitable for precision measurement and data acquisition systems; in terms of temperature stability, the AD826 can maintain its electrical characteristics even in a wide temperature range, which is suitable for applications working in variable ambient temperatures; the AD826 can accept a wide power supply voltage range, which increases the flexibility of the non-inverting proportional amplifier design, and the AD826 supports single power supply, and its maximum single power supply voltage can reach +36V, which meets the design requirements of the present invention.

[0114] ③Selection of R3 and R4 parameters: According to the formula U i2 =U o1 ×R4 / (R3+R4) to determine the value of the voltage divider resistors R3 and R4, so that the in-phase proportional amplifier can work normally within the supply voltage range of the op amp, where U o1 is the output voltage of the voltage comparator. It is the forward saturation voltage of the integrated operational amplifier AD826 when the thyristor overvoltage protection circuit is activated. The power supply voltage of the integrated operational amplifier selected in this example is 24V. At this time, R3 and R4 must work normally without overpower or burning. In this example, R3 is 200Ω and R4 is 100Ω. At this time, U o1 =22V, U i2 =7.34V.

[0115] ④R5, R6 and R F Parameter selection: current limiting resistor R5 = R6 / / R F , according to the formula of the in-phase proportional amplifier gain U o3 / U i2 =(1+R F / R6), you can select R5, R6 and feedback resistor R F The resistance value, where U o3 is the output voltage of the non-inverting proportional amplifier, U i2 For the voltage at the input of the non-inverting proportional amplifier, the selection of R5, R6 and R F When the parameters are set, the non-inverting proportional amplifier is required to work within the supply voltage range and R5, R6 and R F To ensure normal operation without over-power or burning, R5 is selected as 500Ω and R6 is 1kΩ in this example. F is 1kΩ, at this time the amplification factor of the in-phase proportional amplifier is 2 times, U o3 =14.68V.

[0116] ⑤ Selection of transistor T1 and T2 parameters: An OTL complementary symmetrical amplifier circuit is connected after the integrated operational amplifier in the in-phase proportional amplifier circuit to amplify the current. The OTL complementary symmetrical amplifier circuit requires that the characteristics of the NPN transistor T1 and the PNP transistor T2 are symmetrical. In this example, the selected transistor model T1 is 2N5551 and the transistor model T2 is 2N5401.

[0117] ⑥ Selection of diode D1 and D2 parameters: Diodes D1 and D2 mainly play the role of eliminating crossover distortion in the OTL complementary symmetrical amplifier circuit. Therefore, the conduction voltage drop of the selected diodes D1 and D2 should be consistent with the V BE Approximately equal, the D1 and D2 models selected in this example are 1N4007.

[0118] ⑦ Selection of R7 and R8 parameters: When the forward voltage across the thyristor is greater than the protection voltage action value, U o1 Always the forward saturation voltage is 22V, U o3 It is basically unchanged at 14.68V. After selecting the voltage regulator VD1 and the current limiting resistor, the thyristor gate branch current I G is also basically unchanged, then the base current I B_T1 For I B_T1 =I G / (1+β1), then if the transistor T1 is to work in the amplification region, the thyristor supply voltage U CC Should satisfy U CC >U o3 +U BE1 +I B_T1 × R7, according to this formula, the resistance value of the current limiting resistor R7 can be selected. In this example, the transistor supply voltage U CC For 24V, select R7=R8=500Ω, then U CC It should be greater than 17.03V to meet the design requirements.

[0119] ⑧Selection of parameters of voltage regulator VD1, diode D3 and resistor R9: According to the formula U o3 =U Z +U D3 +R9×I G +U G , you can select the voltage regulation value U of the voltage regulator tube Z and the resistance of the current limiting resistor R9, where U Z is the voltage regulation value of the voltage regulator tube, I G is the current value of the thyristor gate branch, U G is the gate voltage of the thyristor. Both should be within the range specified in the thyristor data sheet to enable the thyristor to be stably turned on. At the same time, the resistance of the current limiting resistor R9 should be such that the thyristor gate branch current IG Does not exceed the maximum operating current when the voltage regulator tube VD1 is broken down. o3 =14.68V. The voltage regulator VD1 selected in this example is 1N4734, with a voltage regulation value of 5.6V and a maximum current of 162mA. The diode D3 selected is 1N4007, whose forward voltage drop decreases with increasing temperature. When the thyristor overvoltage protection circuit is working, U D3 =0.77V; the selected current limiting resistor R9 is 65Ω, at this time I G =106.47mA, U G =1.33V. According to the data sheet of thyristor ST1200C12K, the thyristor must be turned on at this time, which meets the design requirements.

[0120] ⑨Resistor R 10 Parameter selection: resistance R 10 Play the role of current limiting, select the resistor R 10 When the thyristor is subjected to the maximum forward voltage, the current flowing through the thyristor should not exceed the maximum current allowed, and R 10 To work properly, without over-power or burning, the resistor R 10 is 100Ω.

[0121] ⑩ Zener diode VD2 and resistor R 12 、R 13 、R 14 and R 15 Parameter selection: According to the formula Then you can select the voltage regulator VD2, where U Z is the voltage across the Zener diode, U CC R 15 The voltage across the terminals, I ZM I is the maximum current allowed to pass through the Zener diode. OM is the current flowing through the current limiting resistor R 15 The maximum current, U1 is the voltage divider resistor R 13 The voltage across the two ends is calculated according to the formula U1 = (2-3)U CC You can select the voltage divider resistor R 12 With R 13 The resistance value is calculated according to the formula I ZM =(1.5~3)I OM You can select the current limiting resistor R 14 With R 15 The power supply voltage of the integrated operational amplifier and transistor selected in this example is 24V, that is, U Z =U CC=24V, select the voltage regulator tube 1N4749, the voltage regulator value of this voltage regulator tube is 24V, and the maximum current allowed to pass is 38mA, that is, I ZM =38mA, select I OM =19mA, then you can select R 14 =1kΩ, R 15 =1.2kΩ, at this time the voltage regulator circuit can stably output 24V voltage.

[0122] As shown in Table 1, the parameters of the selected circuit components are summarized:

[0123] Table 1 Circuit device parameters

[0124]

[0125] Figure 4 、 Figure 5 The following are simulation results of the thyristor withstanding forward overvoltage under two different operating conditions. The protection value set in this simulation is 800V, and the remaining circuit parameters are the same as those in the table above. Figure 4 The simulation condition is that the thyristor is subjected to a forward voltage of 780V at the beginning and a step signal of 820V is applied to the thyristor at 1ms. The simulation result shows that when the thyristor is subjected to a forward voltage of 780V, the protection circuit is not triggered and the current flowing through the thyristor is approximately equal to zero. When the thyristor is subjected to a forward voltage of 820V, the protection circuit is triggered and the thyristor gate branch voltage regulator is broken down. At this time, I G =106.47mA, U G =1.33V. According to the data sheet of thyristor ST1200C12K, the thyristor must be turned on and effectively protected at this time. The seven curves from top to bottom in the figure are U DC 、U i2 、U o2 、U o3 , I G 、U G And the current I flowing through the thyristor AK ,It can be seen from the simulation result curve that the simulation results are consistent with the theoretical analysis, and the thyristor can be effectively protected; Figure 5 The simulation condition is that the thyristor is subjected to a forward voltage of 780V at the beginning. As time increases, the forward voltage borne by the thyristor increases linearly with time in a linear function relationship. At 2ms, the thyristor is subjected to a forward voltage of 820V. It can be seen that when the thyristor is subjected to a forward voltage of 780V to 800V, the protection circuit is not triggered, and the current flowing through the thyristor is approximately equal to zero. When the thyristor is subjected to a forward voltage greater than 800V, the protection circuit is triggered, and the thyristor gate branch voltage regulator is broken down. At this time, I G =106.47mA, U G=1.33V. According to the data sheet of thyristor ST1200C12K, the thyristor must be turned on and effectively protected at this time. The seven curves from top to bottom in the figure are U DC 、U i2 、U o2 、U o3 , I G 、U G And the current I flowing through the thyristor AK ,It can be seen from the simulation result curve that ,the simulation result is consistent with the theoretical analysis and ,the thyristor can be effectively protected.

[0126] In the protection circuit provided by the present invention, when the forward voltage borne by both ends of the thyristor does not reach the protection threshold, the voltage comparator outputs a reverse saturation voltage, the protection circuit does not operate, and the main circuit operates normally; when the forward voltage borne by both ends of the thyristor reaches the protection threshold, the voltage comparator outputs a forward saturation voltage, the voltage regulator is broken down, and a trigger signal for conduction is output to the thyristor gate, causing the thyristor to turn on, thereby realizing overvoltage protection of the thyristor when it is subjected to a forward voltage.

[0127] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit, characterized in that: include: The voltage between the anode and cathode of the thyristor is collected and connected to the non-inverting input of the voltage comparator after voltage division. After passing through the voltage comparator, the op amp outputs a forward saturation or reverse saturation voltage signal; Divide the output of the voltage comparator by resistors; The divided voltage is connected to a current amplification circuit composed of a common-mode proportional amplifier and an OTL complementary symmetrical amplifier circuit; the common-mode proportional amplifier outputs an amplified voltage signal, and the OTL complementary symmetrical amplifier circuit is connected between the output terminal and the feedback terminal of the common-mode proportional amplifier to amplify the output current of the operational amplifier to the current required to turn on the thyristor gate; The output end of the current amplifier circuit is connected to the thyristor gate through a voltage regulator, a diode and a current limiting resistor. When the thyristor is subjected to a forward overvoltage, the voltage regulator breaks down, the thyristor gate is triggered and the thyristor is turned on, thus realizing thyristor overvoltage protection.

2. The method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to claim 1, wherein: include: The anti-temperature drift thyristor overvoltage protection circuit consists of a voltage comparator, a non-inverting proportional amplifier, a diode, a voltage regulator, a transistor, a resistor and a capacitor. Two integrated operational amplifier chips are used in the voltage comparator and the non-inverting proportional amplifier respectively; the resistors include: voltage divider resistors R1, R2, R3, R4, R 12 and R 13 , current limiting resistors R5, R6, R7, R8, R9, R 10 、R 14 、R 15 , feedback resistor R F , loop discharge resistance R 11 The capacitor is C; the diodes are D1, D2 and D3; the voltage regulators include VD1 and VD2; the transistors include NPN tube T1 and PNP tube T2; the thyristor is SCR; The diode D1 is connected between the current limiting resistor R7 and the output of the in-phase proportional amplifier; the diode D2 is connected between the current limiting resistor R8 and the in-phase proportional amplifier; the voltage regulator VD1 is connected between the diode D3 and the emitters of the transistors T1 and T2; the diode D3 is connected between the voltage regulator VD1 and the current limiting resistor R9; the voltage regulator VD2 is connected between the current limiting resistor R 15 In parallel, the current limiting resistor R9 is connected between the diode D3 and the gate of the thyristor SCR; the loop discharge resistor R 11 It is connected in series with the capacitor C and then in parallel with the thyristor SCR; the power supply for the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit is taken from both ends of the thyristor, and after passing through the voltage stabilizing circuit, a stable DC voltage is output to power the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit.

3. The method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to claim 2, wherein: The method of outputting a stable DC voltage after the voltage stabilizing circuit to power the voltage comparator, the in-phase proportional amplifier and the OTL complementary symmetrical amplifier circuit includes: Select the voltage regulator VD2 according to the following formula: Among them U Z is the voltage across the Zener diode, U CC R 15 The voltage across the terminals, I ZM I is the maximum current allowed to pass through the Zener diode. OM is the current flowing through the current limiting resistor R 15 The maximum current, U1 is the voltage divider resistor R 13 The voltage across both ends is determined by the following formula to select the voltage divider resistor R 12 With R 13 Resistance value: U1=(2~3)U CC Select the current limiting resistor R according to the following formula 14 With R 15 Resistance value: IZM=(1.5~3)IOM.

4. The method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to claim 3, wherein: The output forward saturation or reverse saturation voltage signal includes: Assume that the action voltage of the thyristor overvoltage protection circuit is U F , determine the voltage divider resistors R1, R2 and the reference voltage U input to the inverting input of the voltage comparator according to the following formula: ref : IN ref =U F ×R2 / (R1+R2) The voltage after being divided by the voltage divider resistors R1 and R2 is connected to the non-inverting input terminal of the voltage comparator; when the forward voltage across the thyristor is less than the action voltage U of the protection circuit F When the voltage at the non-inverting input of the voltage comparator is less than the voltage at the inverting input, the voltage comparator outputs a reverse saturation voltage signal; when the forward voltage across the thyristor is greater than or equal to the action voltage U of the protection circuit F When , the voltage at the non-inverting input of the voltage comparator is greater than the voltage at the inverting input, and the voltage comparator outputs a forward saturated voltage signal.

5. The method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to claim 4, wherein: The step of dividing the output terminal of the voltage comparator by a resistor comprises: Determine the values ​​of the voltage divider resistors R3 and R4 according to the following formula to ensure that the non-inverting proportional amplifier operates normally within the supply voltage range of the op amp: U i2 =U o1 ×R4 / (R3+R4) Among them U i2 is the voltage at the input of the non-inverting proportional amplifier, U o1 is the output voltage of the voltage comparator.

6. The method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to claim 5, wherein: The step of amplifying the output current of the operational amplifier to a current required for turning on the thyristor gate includes: Set the current limiting resistor R5 = R6 / / R F After selecting the amplification factor of the in-phase proportional amplifier, select R5, R6 and feedback resistor R according to the amplification factor formula of the in-phase proportional amplifier. F The resistance value of the in-phase proportional amplifier is expressed as follows: U o3 / U i2 =(1+R F / R6) Among them U o3 is the output voltage of the non-inverting proportional amplifier, U i2 is the voltage at the input of the non-inverting proportional amplifier.

7. The method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to claim 6, wherein: The step of connecting the output end of the current amplifying circuit to the gate of the thyristor via a voltage regulator tube, a diode and a current limiting resistor comprises: When the forward voltage across the thyristor is greater than the protection voltage action value, the voltage regulator value U is selected. Z The resistance value of the current limiting resistor R9 is as follows: IN o3 =U Z +U D3 +R9×I G +U G Among them U Z is the voltage regulation value of the voltage regulator tube, I G is the current value of the thyristor gate branch, U G is the gate voltage of the thyristor. Both must be within the range specified in the thyristor data sheet that enables the thyristor to be stably turned on.

8. A system using the method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to any one of claims 1 to 7, characterized in that: include: The acquisition module is used to collect the voltage between the anode and cathode of the thyristor, and connect it to the non-inverting input terminal of the voltage comparator after voltage division. After passing through the voltage comparator, the operational amplifier outputs the forward saturation or reverse saturation voltage signal; A voltage divider module is used to divide the output of the voltage comparator through a resistor; The current drive amplifier module is used to connect the divided voltage to the current amplifier circuit composed of a common-mode proportional amplifier and an OTL complementary symmetrical amplifier circuit. The common-mode proportional amplifier outputs an amplified voltage signal, and the OTL complementary symmetrical amplifier circuit is connected between the output terminal and the feedback terminal of the common-mode proportional amplifier to amplify the output current of the operational amplifier to the current required to turn on the thyristor gate. The thyristor overvoltage protection module is used to connect the output end of the current amplifier circuit to the thyristor gate through a voltage regulator, a diode and a current limiting resistor. When the thyristor is subjected to a forward overvoltage, the voltage regulator breaks down, the thyristor gate is triggered, and the thyristor is turned on, thereby realizing thyristor overvoltage protection.

9. A computing device comprising: memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the method for constructing an anti-temperature drift thyristor overvoltage protection circuit according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions, when executed by a processor, implement the steps of the method for constructing a temperature-drift-resistant thyristor overvoltage protection circuit according to any one of claims 1 to 7.

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