An overvoltage protection circuit capable of turning off thyristor and a control method thereof

Abstract

The application discloses a kind of overvoltage protection circuit and control method of turn-off thyristor, belong to electronic circuit technical field, wherein protection circuit includes: turn-off circuit, first opening circuit, second opening circuit and voltage sampling module.The protection circuit of the application realizes when the voltage between the anode and cathode of turn-off thyristor device approaches or exceeds the threshold of voltage resistance in the whole process of driving power-on / power-off, triggers turn-off thyristor device to open, so as to avoid overvoltage breakdown of turn-off thyristor.The protection circuit of the application does not change the structure of existing turn-off thyristor drive circuit, only adds several new circuit modules, and optimizes the on-off characteristic of original turn-off circuit when power-off, greatly reduces the cost of circuit reconstruction, while improving the reliability of action.The protection circuit drive control method of the application can effectively avoid protection circuit malfunction and refusal.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and in particular relates to an overvoltage protection circuit capable of turning off a thyristor and a control method thereof. Background Art

[0002] The integrated gate-commutated thyristor (IGCT) is a new type of switching device used in large-capacity power electronic devices. It primarily consists of a GCT chip encapsulated within a housing and a driver integrated externally. The IGCT driver's primary function is to receive communication signals from the upper-level control system and convert them into voltage and current signals used to switch the GCT chip on and off.

[0003] In addition to IGCT, the driving circuits of other turn-off thyristor devices such as gate turn-off thyristor (GTO), super gate turn-off thyristor (SGTO), emitter-commutated thyristor (ETO), and integrated emitter-commutated thyristor (IETO) are very similar to those of IGCT, and their driving circuits can be improved using the same or similar methods.

[0004] Existing SCR drivers have almost no perfect anode overvoltage protection mechanism. Therefore, when an anode overvoltage occurs in a SCR, it needs to rely on external parallel MOV or other voltage limiting devices for protection, otherwise the device will be broken down.

[0005] Existing thyristor drivers use BOD devices to trigger the thyristor when an anode overvoltage occurs, protecting it from breakdown. Therefore, an MOV is not required in parallel with the thyristor. Compared to MOVs, BOD devices are significantly smaller and less expensive, so they can also be used for anode overvoltage protection in IGCTs.

[0006] Since thyristors lack active shutdown capabilities and naturally shut down when the current crosses zero, the driver does not perform additional processing to ensure reliable device shutdown. Therefore, when the BOD activates, the thyristor can be turned on smoothly. However, during the shutdown period of a turn-off thyristor, the driver applies a reverse voltage to the gate cathode, preventing the trigger current from being generated when the BOD activates. Therefore, additional circuitry is required in the driver to achieve this function. Summary of the Invention

[0007] In view of the above problems, the present invention provides an overvoltage protection circuit and a control method for a turn-off thyristor, which can prevent the turn-off thyristor from overvoltage breakdown.

[0008] An overvoltage protection circuit for a turn-off thyristor device comprises: a turn-off circuit for achieving commutation between the gate and emitter of the turn-off thyristor device according to a control instruction; a first turn-on circuit for triggering the turn-off thyristor device to turn on according to the control instruction; a second turn-on circuit for triggering the turn-off thyristor device to turn on when a second voltage between the anode and the gate of the turn-off thyristor device is higher than a first voltage threshold; and a voltage sampling module for sampling the first voltage between the anode and the cathode of the turn-off thyristor device, or for sampling the second voltage between the anode and the gate of the turn-off thyristor device, and sending a control instruction to the turn-off circuit and the first turn-on circuit when the first voltage is higher than the second voltage threshold or the second voltage is higher than a third voltage threshold.

[0009] Furthermore, the turn-off thyristor device includes an integrated gate-commutated thyristor, a gate-turn-off thyristor or a super gate-turn-off thyristor.

[0010] Furthermore, the turn-off thyristor device includes an emitter-commutated thyristor or an integrated emitter-commutated thyristor.

[0011] Furthermore, the shutdown circuit includes a first shutdown circuit; wherein, the emitter of the turn-off thyristor device is connected to the cathode, the first end of the first shutdown circuit is connected to the gate of the turn-off thyristor device, and the second end of the first shutdown circuit is connected to the cathode of the turn-off thyristor device; the first turn-on circuit and the first turn-off circuit are connected in parallel; the first end of the second turn-on circuit is connected to the anode of the turn-off thyristor device, and the second end of the second turn-on circuit is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the first turn-off circuit; the first end of the voltage sampling module is connected to the first end of the second turn-on circuit and the anode of the turn-off thyristor device, and the second end of the voltage sampling module is connected to the second end of the first turn-on circuit, the second end of the first turn-off circuit, and the cathode of the turn-off thyristor device, or the second end of the voltage sampling module is connected to the first end of the first turn-on circuit, the first end of the first turn-off circuit, and the gate of the turn-off thyristor device.

[0012] Furthermore, the shutdown circuit includes a second shutdown circuit and a third shutdown circuit; wherein, the first end of the third shutdown circuit is connected to the emitter of the turn-off thyristor device, the second end of the third shutdown circuit is connected to the cathode of the turn-off thyristor device, the first end of the second shutdown circuit is connected to the gate of the turn-off thyristor device, and the second end of the second shutdown circuit is connected to the cathode of the turn-off thyristor device; the first turn-on circuit and the second turn-off circuit are connected in parallel; the first end of the second turn-on circuit is connected to the anode of the turn-off thyristor device, the second end of the second turn-on circuit is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the second turn-off circuit, the first end of the voltage sampling module is connected to the first end of the second turn-on circuit and the anode of the turn-off thyristor device, the second end of the voltage sampling module is connected to the second end of the first turn-on circuit, the second end of the second turn-off circuit, and the cathode of the turn-off thyristor device, or the second end of the voltage sampling module is connected to the first end of the first turn-on circuit, the first end of the second turn-off circuit, and the gate of the turn-off thyristor device.

[0013] Furthermore, the second turn-on circuit includes a first BOD component; wherein, the anode of the first BOD component is connected to the anode of the turn-off thyristor device, and the cathode of the first BOD component is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the first turn-off circuit.

[0014] Furthermore, the second turn-on circuit includes a first thyristor and a voltage-stabilizing tube assembly; wherein, the cathode of the first thyristor is connected to the first end of the first turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit, the anode of the first thyristor is connected to the cathode of the voltage-stabilizing tube assembly, the anode of the turn-off thyristor device, and the first end of the voltage sampling module, and the anode of the voltage-stabilizing tube assembly is connected to the gate of the first thyristor.

[0015] Furthermore, the second turn-on circuit includes the first valve group to the Nth valve group, N is a positive integer greater than 1, and each valve group includes a second BOD component and a voltage-equalizing resistor in parallel; wherein, the cathode of the second BOD component in the first valve group is connected to the first end of the first turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit, the anode of the second BOD component in the first valve group is connected to the cathode of the second BOD component in the second valve group, the anode of the second BOD component in the N-1th valve group is connected to the cathode of the second BOD component in the Nth valve group, and the anode of the second BOD component in the Nth valve group is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module.

[0016] Furthermore, the second turn-on circuit includes a third BOD component and a current-limiting resistor connected in series.

[0017] Furthermore, the cathode of the third BOD component is connected to the first end of the first turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the third BOD component is connected to the first end of the current limiting resistor; the second end of the current limiting resistor is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module;

[0018] Alternatively, the anode of the third BOD component is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module, the cathode of the third BOD component is connected to the second end of the current limiting resistor, and the first end of the current limiting resistor is connected to the first end of the first turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit.

[0019] Furthermore, the second turn-on circuit includes a first BOD component; wherein, the anode of the first BOD component is connected to the anode of the turn-off thyristor device, and the cathode of the first BOD component is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the second turn-off circuit.

[0020] Furthermore, the second turn-on circuit includes a first thyristor and a voltage regulator assembly; wherein, the cathode of the first thyristor is connected to the first end of the second turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit, the anode of the first thyristor is connected to the cathode of the voltage regulator assembly, the anode of the turn-off thyristor device, and the first end of the voltage sampling module, and the anode of the voltage regulator assembly is connected to the gate of the first thyristor.

[0021] Furthermore, the second opening circuit includes a first valve group to an Nth valve group, N is a positive integer greater than 1, and each valve group includes a second BOD component and a voltage-sharing resistor connected in parallel;

[0022] Among them, the cathode of the second BOD component in the first valve group is connected to the first end of the second shutdown circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the second BOD component in the first valve group is connected to the cathode of the second BOD component in the second valve group; the anode of the second BOD component in the N-1 valve group is connected to the cathode of the second BOD component in the N valve group; the anode of the second BOD component in the N valve group is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module.

[0023] Furthermore, the second turn-on circuit includes a third BOD component and a current-limiting resistor connected in series.

[0024] Furthermore, the cathode of the third BOD component is connected to the first end of the second turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the third BOD component is connected to the first end of the current limiting resistor; the second end of the current limiting resistor is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module;

[0025] Alternatively, the anode of the third BOD component is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module, the cathode of the third BOD component is connected to the second end of the current limiting resistor, and the first end of the current limiting resistor is connected to the first end of the second turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit.

[0026] Furthermore, the first voltage threshold is lower than the anode breakdown voltage threshold of the turn-off thyristor device, and the second voltage threshold and the third voltage threshold are both lower than the first voltage threshold.

[0027] Furthermore, the breakdown voltage of the first BOD component is equal to the first voltage threshold.

[0028] Furthermore, the overall breakdown voltage of the Zener diode assembly is equal to the first voltage threshold.

[0029] Furthermore, the resistance of the voltage balancing resistor is proportional to the breakdown voltage of the second BOD component, and the sum of the breakdown voltages of the second BOD components in the first valve group to the Nth valve group is equal to the first voltage threshold.

[0030] Furthermore, the breakdown voltage of the third BOD component is equal to the first voltage threshold.

[0031] An embodiment of the present invention further provides a method for controlling an overvoltage protection circuit capable of turning off a thyristor device, comprising the following steps:

[0032] The voltage sampling module collects a first voltage between the anode and cathode of the turn-off thyristor device, or collects a second voltage between the anode and the gate of the turn-off thyristor device, and sends a control instruction to the shutdown circuit and the first opening circuit when the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold;

[0033] The turn-off circuit realizes commutation between the gate and emitter of the turn-off thyristor device according to the control instruction;

[0034] The first turn-on circuit triggers the turn-off thyristor device to turn on according to the control instruction;

[0035] The second turn-on circuit triggers the turn-off thyristor device to turn on when the second voltage between the anode and the gate of the turn-off thyristor device is higher than the first voltage threshold.

[0036] Furthermore, the turn-off thyristor device includes an integrated gate-commutated thyristor, a gate-turn-off thyristor or a super gate-turn-off thyristor, and the turn-off circuit includes a first turn-off circuit.

[0037] Furthermore, the turn-off thyristor device includes an emitter-commutated thyristor or an integrated emitter-commutated thyristor, and the turn-off circuit includes a second turn-off circuit and a third turn-off circuit.

[0038] Furthermore, the control method of the overvoltage protection circuit is used in the following working conditions:

[0039] In the first working condition, the first shut-off circuit, the first open circuit, and the voltage sampling module are all energized;

[0040] In the second working condition, the first shut-off circuit is not energized, and the first open circuit and the voltage sampling module are energized;

[0041] In the third operating condition, the first off circuit and the first on circuit are not energized, and the voltage sampling module is energized;

[0042] In the fourth operating condition, the first shutdown circuit, the first open circuit, and the voltage sampling module are all de-energized.

[0043] Furthermore, in the first operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, it controls the first shutdown circuit to remove the reverse voltage, and at the same time, the voltage sampling module controls the first turn-on circuit to inject a current trigger signal into the gate of the turn-off thyristor device, after which the turn-off thyristor device is triggered to turn on, and the second voltage between the anode and the gate of the turn-off thyristor device does not exceed the first voltage threshold, and the second turn-on circuit does not operate.

[0044] Furthermore, in the second operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the first shutdown circuit does not operate; at the same time, the voltage sampling module controls the first opening circuit to inject a current trigger signal into the gate of the turn-off thyristor device, and then the turn-off thyristor device is triggered to turn on, and the second voltage between the anode and the gate of the turn-off thyristor device does not exceed the first voltage threshold, and the second opening circuit does not operate.

[0045] Furthermore, in the third operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, neither the first shutdown circuit nor the first opening circuit operates, and at this time the first shutdown circuit cannot apply reverse voltage; when the second voltage exceeds the first voltage threshold, the second opening circuit operates and generates a current trigger signal, triggering the turn-off thyristor device to turn on.

[0046] Furthermore, in the fourth operating condition, the first shutdown circuit, the first opening circuit, and the voltage sampling module are all inactive. When the second voltage exceeds the first voltage threshold, the second opening circuit is activated and generates a current trigger signal, triggering the turn-off thyristor device to turn on.

[0047] Furthermore, the control method of the overvoltage protection circuit is used in the following working conditions:

[0048] In the fifth working condition, the first on-circuit, the voltage sampling module, the second off-circuit, and the third off-circuit are all energized;

[0049] In the sixth operating condition, the first open circuit is not energized, and the voltage sampling module, the second shut-off circuit, and the third shut-off circuit are energized;

[0050] In the seventh working condition, the voltage sampling module is energized, and the first open circuit, the second shut-off circuit, and the third shut-off circuit are not energized;

[0051] In the eighth operating condition, the first open circuit, the voltage sampling module, the second shut-off circuit, and the third shut-off circuit are all de-energized.

[0052] Furthermore, in the fifth operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third threshold, the second shutdown circuit is controlled to be disconnected, the third shutdown circuit is controlled to be closed, and at the same time, the first turn-on circuit is controlled to inject a current trigger signal into the gate of the turn-off thyristor device, after which the turn-off thyristor device is triggered to turn on, the second voltage does not exceed the first voltage threshold, and the second turn-on circuit does not operate.

[0053] Furthermore, in the sixth operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the second shutdown circuit is controlled to be disconnected, the third shutdown circuit is controlled to be closed, and the first opening circuit does not operate. When the second voltage exceeds the first voltage threshold, the second opening circuit operates and generates a current trigger signal, and then the thyristor device can be turned off to trigger the opening.

[0054] Furthermore, in the seventh operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the second shutdown circuit, the third shutdown circuit and the first opening circuit do not operate; when the second voltage exceeds the first voltage threshold, the second opening circuit operates and generates a current trigger signal, and then the thyristor device can be turned off to trigger the opening.

[0055] Furthermore, in the eighth operating condition, the first turn-on circuit, the voltage sampling module, the second turn-off circuit, and the third turn-off circuit are all inactive. When the second voltage exceeds the first voltage threshold, the second turn-on circuit is activated and generates a current trigger signal, which can then turn off the thyristor device to trigger the turn-on.

[0056] Furthermore, the second shutdown circuit remains in a normally closed state when power is lost; the third shutdown circuit remains in a normally open state when power is lost; or the third shutdown circuit can be turned into an open state when it is subjected to a positive voltage when power is lost.

[0057] Furthermore, the first voltage threshold is lower than the anode breakdown voltage threshold of the turn-off thyristor device, and the second voltage threshold and the third voltage threshold are both lower than the first voltage threshold.

[0058] Beneficial effects of the present invention:

[0059] 1. The present invention proposes a circuit that can trigger the turn-off thyristor device to turn on when the voltage across the anode and cathode of the turn-off thyristor device approaches or exceeds the withstand voltage threshold during the entire process of driving power on / off, thereby avoiding overvoltage breakdown of the turn-off thyristor.

[0060] 2. The protection circuit of the present invention does not change the structure of the existing turn-off thyristor drive circuit, but only adds several new circuit modules and optimizes the on-off characteristics of the original turn-off circuit when the power is off, which greatly reduces the cost of circuit modification and improves the reliability of the operation.

[0061] 3. The protection circuit driving control method of the present invention can effectively avoid malfunction and failure of the protection circuit.

[0062] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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 work.

[0064] Figure 1 A first overall structural diagram of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention is shown;

[0065] Figure 2 A second overall schematic diagram of an overvoltage protection circuit for a turn-off thyristor device according to the present invention is shown;

[0066] Figure 3 FIG2 shows a schematic structural diagram of a first embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention;

[0067] Figure 4 FIG2 shows a schematic structural diagram of a second embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention;

[0068] Figure 5 FIG2 shows a schematic structural diagram of a third embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention;

[0069] Figure 6 FIG4 is a structural diagram of a fourth embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention;

[0070] Figure 7 A structural schematic diagram of a fifth embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention is shown.

[0071] In the figure: 1. Turn-off thyristor device; 2. First turn-off circuit; 3. First turn-on circuit; 4. Second turn-on circuit; 5. Voltage sampling module; 6. Second turn-off circuit; 7. Third turn-off circuit; 11. Anode of turn-off thyristor device; 12. Cathode of turn-off thyristor device; 13. Gate of turn-off thyristor device; 14. Emitter of turn-off thyristor device; 21. First capacitor; 22. First switching element; 31. Second capacitor; 32. Trigger circuit; 41. First BOD component; 42. First thyristor; 43. Zener diode component; 44. First valve group; 45. Nth valve group; 441. Second BOD component; 442. Equalizing resistor; 46. Third BOD component; 47. Current limiting resistor; 61. Second switching element; 71. Third switching element. DETAILED DESCRIPTION

[0072] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0073] An embodiment of the present invention provides an overvoltage protection circuit for a turn-off thyristor device, which can trigger the turn-off thyristor device 1 to turn on when the voltage across the anode and cathode or the voltage across the anode gate of the turn-off thyristor device approaches or exceeds the withstand voltage threshold during the entire process of driving power on / off, thereby avoiding overvoltage breakdown of the turn-off thyristor device 1.

[0074] An overvoltage protection circuit capable of turning off a thyristor device comprises a turn-off circuit, a first turn-on circuit 3, a second turn-on circuit 4 and a voltage sampling module 5.

[0075] The turn-off circuit is used to realize commutation between the gate 13 of the turn-off thyristor device and the emitter 14 of the turn-off thyristor device according to the control instruction.

[0076] It should be noted that the commutation between the gate electrode 13 of the turn-off thyristor device and the emitter electrode 14 of the turn-off thyristor device can cause the turn-off thyristor device 1 to be turned off naturally.

[0077] The first turn-on circuit 3 is used to trigger the turn-off thyristor device 1 to turn on according to a control instruction.

[0078] The second turn-on circuit 4 is configured to trigger the turn-off thyristor device 1 to turn on when a second voltage between the anode 11 and the gate 13 of the turn-off thyristor device is higher than a first voltage threshold.

[0079] The voltage sampling module 5 is used to collect a first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device, or to collect a second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device. When the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold, a control instruction is sent to the shutdown circuit and the first opening circuit 3.

[0080] It should be noted that the voltage sampling module 5 mainly collects the anode voltage, and its reference point can be the gate 13 of the turn-off thyristor device or the cathode 12 of the turn-off thyristor device, which mainly depends on which point is more convenient to use as a reference when designing the circuit. It has no effect on the actual circuit operation and protection process.

[0081] The overvoltage protection circuit of the embodiment of the present invention does not change the structure of the existing turn-off thyristor driving circuit, but only adds a second turn-on circuit 4 and a voltage sampling module 5, which greatly reduces the cost of circuit modification and improves the reliability of the operation.

[0082] Specifically, the turn-off thyristor device 1 includes an integrated gate-commutated thyristor (IGCT), a gate-turn-off thyristor (GTO), a super gate-turn-off thyristor (SGTO), an emitter-commutated thyristor (ETO), or an integrated emitter-commutated thyristor (IETO).

[0083] It should be noted that the turn-off circuit of the integrated gate-commutated thyristor (IGCT), gate-turn-off thyristor (GTO), and super gate-turn-off thyristor (SGTO) drive circuit includes a first turn-off circuit 2; the turn-off circuit of the emitter-commutated thyristor (ETO) and integrated emitter-commutated thyristor (IETO) drive circuit includes a second turn-off circuit 6 and a third turn-off circuit 7.

[0084] In the embodiment of the present invention, an overvoltage protection circuit is provided for different turn-off circuits of the turn-off thyristor device 1 .

[0085] See also Figure 1 , Figure 1 A first overall structural schematic diagram of an overvoltage protection circuit for a turn-off thyristor device according to the present invention is shown.

[0086] Figure 1 The overvoltage protection circuit structure shown is applied to an integrated gate-commutated thyristor (IGCT), a gate-turn-off thyristor (GTO), or a super gate-turn-off thyristor (SGTO).

[0087] For example, when the voltage sampling module 5 is used to collect the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device, the circuit structure is as follows: Figure 1 shown.

[0088] Specifically, the emitter 14 of the turn-off thyristor device is connected to the cathode 12 of the turn-off thyristor device, the first end of the first turn-off circuit 2 is connected to the gate 13 of the turn-off thyristor device, and the second end of the first turn-off circuit 2 is connected to the cathode 12 of the turn-off thyristor device; the first turn-on circuit 3 and the first turn-off circuit 2 are connected in parallel; the first end of the second turn-on circuit 4 is connected to the anode 11 of the turn-off thyristor device, and the second end of the second turn-on circuit 4 is connected to the gate 13 of the turn-off thyristor device, the first end of the first turn-on circuit 3, and the first end of the first turn-off circuit 2.

[0089] When the cathode 12 of the turn-off thyristor device is taken as a reference point, the first end of the voltage sampling module 5 is connected to the first end of the second turn-on circuit 4 and the anode 11 of the turn-off thyristor device, and the second end of the voltage sampling module 5 is connected to the second end of the first turn-on circuit 3, the second end of the first turn-off circuit 2, and the cathode 12 of the turn-off thyristor device.

[0090] When the gate 13 of the turn-off thyristor device is taken as a reference point, the first end of the voltage sampling module 5 is connected to the first end of the second turn-on circuit 4 and the anode 11 of the turn-off thyristor device, and the second end of the voltage sampling module 5 is connected to the first end of the first turn-on circuit 3, the first end of the first turn-off circuit 2, and the gate 13 of the turn-off thyristor device.

[0091] When the overvoltage protection circuit is powered on, the voltage sampling module 5 collects the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device, or collects the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device. When the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold, and the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is not higher than the first voltage threshold, the voltage sampling module 5 controls the first turn-off circuit 2 and the first turn-on circuit 3 to act accordingly, and the first turn-on circuit 3 triggers the turn-off thyristor device 1 to turn on.

[0092] When the second voltage is higher than the first voltage threshold, the second turn-on circuit 4 triggers the turn-off thyristor device 1 to turn on.

[0093] When the overvoltage protection circuit loses power, when the second voltage is higher than the first voltage threshold, the second turn-on circuit 4 triggers the turn-off thyristor device 1 to turn on.

[0094] When the first shutdown circuit 2 and the first opening circuit 3 are energized, the first shutdown circuit 2 applies a reverse voltage between the gate 13 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device after receiving the shutdown instruction issued by the voltage sampling module 5, and cuts off this branch after receiving the opening instruction issued by the voltage sampling module 5; the first opening circuit 3 injects a trigger current into the gate 13 of the turn-off thyristor device after receiving the opening instruction issued by the voltage sampling module 5, and cuts off this branch after receiving the shutdown instruction.

[0095] The second opening circuit 4 is an opening circuit for realizing the overvoltage protection function. Regardless of whether the first shutdown circuit 2, the first opening circuit 3 and the voltage sampling module 5 are energized, it is opened when the voltage at both ends thereof is higher than the first voltage threshold, so that a trigger current is injected from the anode 11 of the turn-off thyristor device to the gate 13 of the turn-off thyristor device, triggering the turn-off thyristor device 1 to turn on, thereby avoiding overvoltage breakdown.

[0096] The first voltage threshold is lower than the breakdown voltage threshold of the anode 11 of the turn-off thyristor device, and the second voltage threshold and the third voltage threshold are both lower than the first voltage threshold.

[0097] The voltage sampling module 5 is a sampling circuit for realizing the overvoltage protection function. When the first shutdown circuit 2 and the first opening circuit 3 are energized, when the first voltage is higher than the second voltage threshold or the second voltage is higher than the third threshold, a control signal is generated and input to the first shutdown circuit 2 and the first opening circuit 3. The first shutdown circuit 2 and the first opening circuit 3 take corresponding actions according to the actual operating conditions.

[0098] See also Figure 2 , Figure 2 A second overall structural schematic diagram of an overvoltage protection circuit for a turn-off thyristor device according to the present invention is shown.

[0099] like Figure 2 As shown, an embodiment of the present invention further provides an overvoltage protection circuit structure applied to an emitter-commutated thyristor (ETO) or an integrated emitter-commutated thyristor (IETO).

[0100] Specifically, the first end of the third turn-off circuit 7 is connected to the emitter 14 of the turn-off thyristor device, the second end of the third turn-off circuit 7 is connected to the cathode 12 of the turn-off thyristor device, the first end of the second turn-off circuit 6 is connected to the gate 13 of the turn-off thyristor device, and the second end of the second turn-off circuit 6 is connected to the cathode 12 of the turn-off thyristor device; the first turn-on circuit 3 and the second turn-off circuit 6 are connected in parallel; the first end of the second turn-on circuit 4 is connected to the anode 11 of the turn-off thyristor device, and the second end of the second turn-on circuit 4 is connected to the gate 13 of the turn-off thyristor device, the first end of the first turn-on circuit 3, and the first end of the second turn-off circuit 6.

[0101] When the gate 13 of the turn-off thyristor device is taken as a reference point, the first end of the voltage sampling module 5 is connected to the first end of the second turn-on circuit 4 and the anode 11 of the turn-off thyristor device, and the second end of the voltage sampling module 5 is connected to the second end of the first turn-on circuit 3, the second end of the second turn-off circuit 6, and the cathode 12 of the turn-off thyristor device.

[0102] When the cathode 12 of the turn-off thyristor device is taken as a reference point, the first end of the voltage sampling module 5 is connected to the first end of the second turn-on circuit 4 and the anode 11 of the turn-off thyristor device, and the second end of the voltage sampling module 5 is connected to the first end of the first turn-on circuit 3, the first end of the second turn-off circuit 6, and the gate 13 of the turn-off thyristor device.

[0103] When the second shut-down circuit 6, the third shut-down circuit 7, and the first opening circuit 3 are energized, after receiving a shut-down instruction from the voltage sampling module 5, the second shut-down circuit 6 short-circuits the gate 13 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device, and the third shut-down circuit 7 opens the emitter 14 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device. After receiving an opening instruction from the voltage sampling module 5, the second shut-down circuit 6 opens the gate 13 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device, and the third shut-down circuit 7 short-circuits the emitter 14 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device. After receiving an opening instruction from the voltage sampling module 5, the first opening circuit 3 injects a trigger current into the gate 13 of the turn-off thyristor device and disconnects the current branch upon receiving a shut-down instruction.

[0104] It should be noted that when energized, the closing and opening of the second shutdown circuit 6 and the third shutdown circuit 7 are controlled by the voltage sampling module 5; when not energized, the second shutdown circuit 6 presents a normally-off characteristic, the third shutdown circuit 7 presents a normally-on characteristic, or the third shutdown circuit 7 presents a characteristic of being turned on after the voltage at both ends exceeds a certain threshold.

[0105] In this embodiment, when the second shutdown circuit 6, the third shutdown circuit 7 and the first open circuit 3 are energized, the voltage sampling module 5 generates a control signal when the first voltage is higher than the second voltage threshold, and inputs it to the second shutdown circuit 6, the third shutdown circuit 7 and the first open circuit 3. The second shutdown circuit 6, the third shutdown circuit 7 and the first open circuit 3 take corresponding actions according to the actual operating conditions.

[0106] In the following embodiment, the voltage sampling module 5 collects the first voltage between the anode 11 and the cathode 12 of the turn-off thyristor device to exemplarily illustrate the overvoltage protection circuit of the turn-off thyristor device 1 of the present invention.

[0107] See also Figure 1 and Figure 3 , Figure 3A structural schematic diagram of a first embodiment of an overvoltage protection circuit for a turn-off thyristor device according to the present invention is shown.

[0108] In one embodiment, the second turn-on circuit 4 includes a first BOD component 41 .

[0109] Specifically, when the overvoltage protection circuit structure is applied to an integrated gate-commutated thyristor (IGCT), a gate-turn-off thyristor (GTO) or a super gate-turn-off thyristor (SGTO), the anode of the first BOD component 41 is connected to the anode 11 of the turn-off thyristor device, and the cathode of the first BOD component 41 is connected to the gate 13 of the turn-off thyristor device, the first end of the first turn-on circuit 3, and the first end of the first turn-off circuit 2.

[0110] For example, the first turn-off circuit 2 includes a first capacitor 21 and a first switch element 22 connected in series, and the first turn-on circuit 3 includes a second capacitor 31 and a trigger circuit 32 .

[0111] It should be noted that the positions of the first capacitor 21 and the first switch element 22 can be interchanged. Figure 2 The connection method in is for example only.

[0112] The first connection method, such as Figure 3 As shown, the positive electrode of the first capacitor 21 is connected to the cathode 12 of the turn-off thyristor device and the negative electrode of the second capacitor 31, the first end of the first switching element 22 is connected to the negative electrode of the first capacitor 21, the second end of the first switching element 22 is connected to the gate 13 of the turn-off thyristor device, the second end of the trigger circuit 32, and the cathode of the first BOD component 41, the positive electrode of the second capacitor 31 is connected to the first end of the trigger circuit 32, the anode of the first BOD component 41 is connected to the anode 11 of the turn-off thyristor device, and the voltage sampling module 5 controls the operation of the first switching element 22 and the trigger circuit 32.

[0113] In the second connection mode, the negative electrode of the first capacitor 21 is connected to the gate 13 of the turn-off thyristor device, the second end of the trigger circuit 32, and the cathode of the first BOD component 41, the positive electrode of the first capacitor 21 is connected to the second end of the first switching element 22, the first end of the first switching element 22 is connected to the cathode 12 of the turn-off thyristor device and the negative electrode of the second capacitor 31, the positive electrode of the second capacitor 31 is connected to the first end of the trigger circuit 32, and the anode of the first BOD component 41 is connected to the anode 11 of the turn-off thyristor device.

[0114] Specifically, upon receiving a shutdown instruction, the voltage sampling module 5 controls the first switching element 22 to close, short-circuiting the cathode of the first capacitor 21 and the gate 13 of the turn-off thyristor device, thereby applying a reverse voltage to the gate 13 and cathode 12 of the turn-off thyristor device. Upon receiving a turn-on instruction, the voltage sampling module 5 controls the first switching element 22 to open, opening the circuit between the cathode of the first capacitor 21 and the gate 13 of the turn-off thyristor device, and removing the reverse voltage.

[0115] Upon receiving an on command, the trigger circuit 32 operates to inject a current trigger signal of a specific waveform into the gate electrode 13 of the turn-off thyristor device, thereby triggering the turn-off thyristor device 1 to turn on. Upon receiving an off command, the trigger circuit 32 deactivates, opening the circuit between the positive electrode of the second capacitor 31 and the gate electrode 13 of the turn-off thyristor device, thereby removing the current.

[0116] The first BOD component 41 is a BOD component with reverse voltage withstand capability. It can be a BOD element with a fast recovery diode integrated in the package, or a discrete fast recovery diode and a BOD element connected in series. The breakdown voltage of the first BOD component 41 is equal to the first voltage threshold.

[0117] When the second voltage between the SCR device anode 11 and the SCR device gate 13 exceeds the first voltage threshold, the first BOD component 41 breaks down, short-circuiting the SCR device anode 11 and the SCR device gate 13. This injects a short current pulse into the SCR device gate 13, triggering the SCR device 1 to turn on. At this point, the first switching element 22 must be disconnected; otherwise, the injected current pulse will be absorbed by the first capacitor 21, failing to achieve the desired effect.

[0118] See also Figure 4 , Figure 4 A structural schematic diagram of a second embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention is shown.

[0119] Specifically, when the overvoltage protection circuit structure is applied to an emitter-commutated thyristor (ETO) or an integrated emitter-commutated thyristor (IETO), the anode of the first BOD component 41 is connected to the anode 11 of the turn-off thyristor device, and the cathode of the first BOD component 41 is connected to the gate 13 of the turn-off thyristor device, the first end of the first turn-on circuit 3, and the first end of the second turn-off circuit 6.

[0120] For example, the second shutdown circuit 6 includes a second switch element 61 , and the third shutdown circuit 7 includes a third switch element 71 .

[0121] The first end of the third switching element 71 is connected to the emitter 14 of the turn-off thyristor device, the second end of the third switching element 71 is connected to the cathode 12 of the turn-off thyristor device, the first end of the second switching element 61 is connected to the gate 13 of the turn-off thyristor device, the cathode of the first BOD component 41, and the second end of the trigger circuit 32, the positive electrode of the second capacitor 31 is connected to the first end of the trigger circuit 32, the negative electrode of the second capacitor 31 is connected to the second end of the second switching element 61 and the cathode 12 of the turn-off thyristor device, and the anode of the first BOD component 41 is connected to the anode 11 of the turn-off thyristor device.

[0122] Upon receiving an on command, the trigger circuit 32 operates, injecting a current trigger signal of a specific waveform into the gate 13 of the turn-off thyristor device. The current trigger signal forms a loop through the emitter 14 of the turn-off thyristor device, the third switching element 71, and the cathode 12 of the turn-off thyristor device, thereby triggering the turn-off thyristor device 1 to turn on. Upon receiving a off command, the trigger circuit 32 deactivates, opening the circuit between the positive electrode of the second capacitor 31 and the gate 13 of the turn-off thyristor device, removing the current.

[0123] When the second voltage between the SCR device anode 11 and the SCR device gate 13 exceeds the first voltage threshold, the first BOD component 41 breaks down, short-circuiting the SCR device anode 11 and the SCR device gate 13. This injects a short current pulse into the SCR device gate 13, triggering the SCR device 1 to turn on. At this point, the second switch element 61 must be open and the third switch element 71 closed; otherwise, the injected current pulse will be bypassed by the second switch element 61, failing to achieve the desired effect.

[0124] It should be noted that the above implementations of the first shut-down circuit 2 , the second shut-down circuit 6 , the third shut-down circuit 7 and the first enable circuit 3 are exemplary descriptions of the prior art.

[0125] The advantages of this embodiment are simple structure and good consistency of protection thresholds.

[0126] In this embodiment, the second opening circuit 4 is implemented by, but not limited to, a BOD component, a thyristor component, a resistor, a diode, a gas discharge tube, and the like.

[0127] In the following embodiments, the structure of the second turn-on circuit 4 is exemplified by applying the overvoltage protection circuit structure to an integrated gate-commutated thyristor (IGCT), a gate-turn-off thyristor (GTO), or a super gate-turn-off thyristor (SGTO).

[0128] See also Figure 5 , Figure 5 A structural schematic diagram of a third embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention is shown.

[0129] In one embodiment, the second turn-on circuit 4 includes a first thyristor 42 and a voltage-stabilizing tube assembly 43, wherein the cathode of the first thyristor 42 is connected to the second end of the first switching element 22, the gate 13 of the turn-off thyristor device, and the second end of the trigger circuit 32, the anode of the first thyristor 42 is connected to the cathode of the voltage-stabilizing tube assembly 43, the anode 11 of the turn-off thyristor device, and the first end of the voltage sampling module 5, and the anode of the voltage-stabilizing tube assembly 43 is connected to the gate of the first thyristor 42.

[0130] The overall breakdown voltage of the voltage regulator tube assembly 43 is equal to the first voltage threshold, and the voltage regulator tube assembly 43 may be a single voltage regulator tube component or a plurality of voltage regulator tubes connected in series.

[0131] When the second voltage between the anode 11 and the gate 13 of the turn-off thyristor device exceeds the first voltage threshold, the voltage-stabilizing tube assembly 43 breaks down, generating a current signal that triggers the first thyristor 42 to turn on. This short-circuits the anode 11 and the gate 13 of the turn-off thyristor device, injecting a short current pulse into the gate 13 of the turn-off thyristor device, triggering the turn-off thyristor device 1 to turn on. At this point, it is necessary to ensure that the first switching element 22 is disconnected; otherwise, the injected current pulse will be absorbed by the first capacitor 21, failing to achieve the desired effect.

[0132] The advantages of this embodiment are strong surge current tolerance and good triggering characteristics.

[0133] See also Figure 6 , Figure 6 A structural schematic diagram of a fourth embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention is shown.

[0134] In one embodiment, the second opening circuit 4 includes a first valve group 44 to an Nth valve group 45, where N is a positive integer greater than 1, and each valve group includes a second BOD component 441 and a voltage-equalizing resistor 442 connected in parallel. The cathode of the second BOD component 441 in the first valve group 44 is connected to the second end of the first switching element 22, the gate 13 of the turn-off thyristor device, and the second end of the trigger circuit 32. The anode of the second BOD component 441 in the first valve group 44 is connected to the cathode of the second BOD component 441 in the second valve group. The anode of the second BOD component 441 in the N-1th valve group is connected to the cathode of the second BOD component 441 in the Nth valve group 45. The anode of the second BOD component 441 in the Nth valve group 45 is connected to the anode 11 of the turn-off thyristor device and the first end of the voltage sampling module 5.

[0135] It should be noted that the second BOD component 441 is the same as the first BOD component 41, the resistance of the equalizing resistor 442 is proportional to the breakdown voltage of the second BOD component 441, and the sum of the breakdown voltages of the second BOD components 441 in the first valve group 44 to the Nth valve group 45 is equal to the first voltage threshold.

[0136] When the second voltage across the SCR device anode 11 and the SCR device gate 13 exceeds the first voltage threshold, all second BOD components 441 in the first valve group 44 through the Nth valve group 45 are broken down, thereby short-circuiting the SCR device anode 11 and the SCR device gate 13 and injecting a short current pulse into the SCR device gate 13, triggering the SCR device 1 to turn on. At this point, the first switching element 22 must be disconnected; otherwise, the injected current pulse will be absorbed by the first capacitor 21, failing to achieve the desired effect.

[0137] The advantage of this embodiment is that the first voltage threshold has a wide selectable range.

[0138] See also Figure 7 , Figure 7 A structural schematic diagram of a fifth embodiment of an overvoltage protection circuit capable of turning off a thyristor device according to the present invention is shown.

[0139] In one embodiment, the second turn-on circuit 4 includes a third BOD component 46 and a current-limiting resistor 47 connected in series.

[0140] In the first connection mode, the cathode of the third BOD component 46 is connected to the second end of the first switching element 22, the gate 13 of the turn-off thyristor device, and the second end of the trigger circuit 32; the anode of the third BOD component 46 is connected to the first end of the current limiting resistor 47; the second end of the current limiting resistor 47 is connected to the anode 11 of the turn-off thyristor device and the first end of the voltage sampling module 5.

[0141] In the second connection method, the anode of the third BOD component 46 is connected to the anode 11 of the turn-off thyristor device and the first end of the voltage sampling module 5, the cathode of the third BOD component 46 is connected to the second end of the current limiting resistor 47, and the first end of the current limiting resistor 47 is connected to the second end of the first switching element 22, the gate 13 of the turn-off thyristor device, and the second end of the trigger circuit 32.

[0142] It should be noted that the third BOD component 46 is the same as the first BOD component 41 , and the breakdown voltage of the third BOD component 46 is equal to the first voltage threshold.

[0143] When the second voltage across the anode 11 and gate 13 of the turn-off thyristor device exceeds the first voltage threshold, the third BOD component 46 breaks down, leaving only the current-limiting resistor 47 between the anode 11 and gate 13 of the turn-off thyristor device. A short current pulse is limited by the current-limiting resistor 47 to the gate 13 of the turn-off thyristor device, triggering the turn-off thyristor device 1 to turn on. At this time, the first switching element 22 must be turned off; otherwise, the injected current pulse will be absorbed by the first capacitor 21, failing to achieve the desired effect.

[0144] The advantage of this embodiment is that the injected trigger current is limited by the current limiting resistor 47 , thereby preventing the turn-off thyristor device 1 and the third BOD component 46 from being damaged.

[0145] It should be noted that the above embodiment only provides the simplest solution. Obviously, in all the above embodiments, a current limiting resistor 47 can be connected in series in the second opening circuit 4 to achieve the corresponding function, so no more examples are given.

[0146] Those skilled in the art should understand that the second turn-on circuit 4 in the above embodiment can be applied to an overvoltage protection circuit of an emitter-commutated thyristor (ETO) or an integrated emitter-commutated thyristor (IETO), and details thereof will not be repeated.

[0147] The embodiment of the present invention further provides a control method coordinated with the overvoltage protection circuit of the aforementioned turn-off thyristor device 1 , which can effectively prevent the protection circuit from malfunctioning or failing to operate.

[0148] A method for controlling an overvoltage protection circuit capable of shutting off a thyristor device comprises the following steps:

[0149] The turn-off circuit realizes commutation between the gate 13 and the emitter 14 of the turn-off thyristor device according to the control instruction.

[0150] In this step, commutation between the gate 13 and the emitter 14 of the turn-off thyristor device is achieved by applying a reverse voltage to the gate 13 and the cathode 12 of the turn-off thyristor device; or controlling the turn-off circuit to be opened; or controlling the turn-off circuit to be closed.

[0151] The first turn-on circuit 3 triggers the turn-off thyristor device 1 to turn on according to the control instruction.

[0152] The second turn-on circuit 4 triggers the turn-off thyristor device 1 to turn on when the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third voltage threshold.

[0153] The voltage sampling module 5 collects a first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device, or collects a second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device. When the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold, a control instruction is sent to the shutdown circuit and the first opening circuit 3.

[0154] See also Figure 1 and Figure 3 When the control method of the overvoltage protection circuit of the turn-off thyristor device 1 according to the embodiment of the present invention is applied to an integrated gate-commutated thyristor (IGCT), a gate-turn-off thyristor (GTO), or a super gate-turn-off thyristor (SGTO), the power-on conditions of the first turn-off circuit 2, the first turn-on circuit 3, and the voltage sampling module 5 are different. Generally, during the power-on and power-off processes of the first turn-off circuit 2, the first turn-on circuit 3, and the voltage sampling module 5, the voltage sampling module 5 is powered on first and powered off last, followed by the first turn-on circuit 3, and the first turn-off circuit 2 is powered on last and powered off first. Therefore, the power-on conditions of the three circuits are divided into the following four categories:

[0155] In the first working condition, the first shut-off circuit 2 , the first opening circuit 3 , and the voltage sampling module 5 are all energized.

[0156] In the second working condition, the first shut-off circuit 2 is not energized, and the first opening circuit 3 and the voltage sampling module 5 are energized.

[0157] In the third operating condition, the first shut-off circuit 2 and the first opening circuit 3 are not energized, and the voltage sampling module 5 is energized.

[0158] In the fourth working condition, the first shut-off circuit 2 , the first opening circuit 3 , and the voltage sampling module 5 are all de-energized.

[0159] The control methods for the above four working conditions are:

[0160] For the first operating condition, when the voltage sampling module 5 detects that the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device is higher than the second voltage threshold, or detects that the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third threshold, the first turn-off circuit 2 is controlled to remove the reverse voltage, and at the same time, the first turn-on circuit 3 is controlled to inject a current trigger signal into the gate 13 of the turn-off thyristor device. After that, the turn-off thyristor device 1 is triggered to turn on, and the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device does not exceed the first voltage threshold, and the second turn-on circuit 4 does not work.

[0161] For the second operating condition, when the voltage sampling module 5 detects that the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device is higher than the second voltage threshold, or detects that the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third voltage threshold, the first turn-off circuit 2 does not operate; at the same time, the voltage sampling module 5 controls the first turn-on circuit 3 to inject a current trigger signal into the gate 13 of the turn-off thyristor device, and then the turn-off thyristor device 1 is triggered to turn on, and the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device does not exceed the first voltage threshold, and the second turn-on circuit 4 does not operate.

[0162] For the third operating condition, when the voltage sampling module 5 detects that the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device is higher than the second voltage threshold, or detects that the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third voltage threshold, the first turn-off circuit 2 and the first turn-on circuit 3 are both inoperative. At this time, the first turn-off circuit 2 loses power and is unable to apply reverse voltage. When the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device exceeds the first voltage threshold, the second turn-on circuit 4 is activated and generates a current trigger signal, and then the turn-off thyristor device 1 is triggered to turn on.

[0163] For the fourth operating condition, the first shutdown circuit 2, the first opening circuit 3, and the voltage sampling module 5 are all inactive. When the second voltage exceeds the first voltage threshold, the second opening circuit 4 is activated and generates a current trigger signal, which can then turn off the thyristor device 1 and trigger it to open.

[0164] See also Figure 2 and Figure 4 When the control method of the overvoltage protection circuit of the turn-off thyristor device 1 according to the embodiment of the present invention is applied to an emitter-commutated thyristor (ETO) or an integrated emitter-commutated thyristor (IETO), the power-on conditions of the first turn-on circuit 3, the voltage sampling module 5, the second turn-off circuit 6, and the third turn-off circuit 7 are different. Generally, during the power-on and power-off processes of the first turn-on circuit 3, the voltage sampling module 5, the second turn-off circuit 6, and the third turn-off circuit 7, the voltage sampling module 5 is powered on first and powered off last, followed by the second turn-off circuit 6 and the third turn-off circuit 7. The first turn-on circuit 3 is powered on last and powered off first. Therefore, the power-on conditions of the three circuits are divided into the following four categories:

[0165] In the fifth working condition, the first open circuit 3, the voltage sampling module 5, the second shutoff circuit 6, and the third shutoff circuit 7 are all energized.

[0166] In the sixth operating condition, the first open circuit 3 is not energized, and the voltage sampling module 5, the second shut-off circuit 6, and the third shut-off circuit 7 are energized.

[0167] In the seventh working condition, the voltage sampling module 5 is energized, and the first open circuit 3, the second shutoff circuit 6, and the third shutoff circuit 7 are not energized.

[0168] In the eighth working condition, the first open circuit 3, the voltage sampling module 5, the second shut-off circuit 6, and the third shut-off circuit 7 are all de-energized.

[0169] It should be noted that the second shutdown circuit remains in a normally closed state when power is lost; the third shutdown circuit remains in a normally open state when power is lost; or the third shutdown circuit can become conductive when it is subjected to positive voltage when power is lost.

[0170] The control methods for the above four working conditions from the fifth to the eighth are:

[0171] For the fifth operating condition, when the voltage sampling module 5 detects that the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device is higher than the second voltage threshold, or detects that the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third threshold, the second turn-off circuit 6 is controlled to be disconnected, the third turn-off circuit 7 is controlled to be closed, and the first turn-on circuit 3 is controlled to inject a current trigger signal into the gate 13 of the turn-off thyristor device. After that, the turn-off thyristor device 1 is triggered to turn on, the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device does not exceed the first voltage threshold, and the second turn-on circuit 4 does not work.

[0172] For the sixth operating condition, when the voltage sampling module 5 detects that the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device is higher than the second voltage threshold, or detects that the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third voltage threshold, the second turn-off circuit 6 is controlled to be disconnected, the third turn-off circuit 7 is controlled to be closed, the first turn-on circuit 3 does not operate, and when the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device exceeds the first voltage threshold, the second turn-on circuit 4 operates and generates a current trigger signal, and then the turn-off thyristor device 1 is triggered to open.

[0173] For the seventh operating condition, when the voltage sampling module 5 detects that the first voltage between the anode 11 of the turn-off thyristor device and the cathode 12 of the turn-off thyristor device is higher than the second voltage threshold, or detects that the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device is higher than the third voltage threshold, the second turn-off circuit 6, the third turn-off circuit 7 and the first turn-on circuit 3 are all inoperative, and the second turn-off circuit 6 is in a normally-off state; when the second voltage between the anode 11 of the turn-off thyristor device and the gate 13 of the turn-off thyristor device exceeds the first voltage threshold, the second turn-on circuit 4 is operated and generates a current trigger signal, and then the turn-off thyristor device 1 is triggered to turn on;

[0174] For the eighth operating condition, the first turn-on circuit 3, the voltage sampling module 5, the second turn-off circuit 6, and the third turn-off circuit 7 are all inactive. When the second voltage exceeds the first voltage threshold, the second turn-on circuit 4 is activated and generates a current trigger signal, which can then turn off the thyristor device 1 to trigger the turn-on.

[0175] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An overvoltage protection circuit capable of turning off a thyristor device, characterized in that: include: A turn-off circuit, used to realize commutation between the gate and emitter of the turn-off thyristor device according to a control instruction; A first turn-on circuit is used to trigger the turn-off thyristor device to turn on according to a control instruction; a second turn-on circuit, configured to trigger the turn-off thyristor device to turn on when a second voltage between the anode and the gate of the turn-off thyristor device is higher than a first voltage threshold; a voltage sampling module, configured to collect a first voltage between the anode and cathode of the turn-off thyristor device, or to collect a second voltage between the anode and gate of the turn-off thyristor device, and to send a control instruction to the turn-off circuit or the first turn-on circuit when the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold; The turn-off circuit includes a first turn-off circuit; wherein the emitter of the turn-off thyristor device is connected to the cathode, the first end of the first turn-off circuit is connected to the gate of the turn-off thyristor device, and the second end of the first turn-off circuit is connected to the cathode of the turn-off thyristor device; the first turn-on circuit and the first turn-off circuit are connected in parallel; The first end of the second open circuit is connected to the anode of the turn-off thyristor device, and the second end of the second open circuit is connected to the gate of the turn-off thyristor device, the first end of the first open circuit, and the first end of the first turn-off circuit; the first end of the voltage sampling module is connected to the first end of the second open circuit and the anode of the turn-off thyristor device, and the second end of the voltage sampling module is connected to the second end of the first open circuit, the second end of the first turn-off circuit, and the cathode of the turn-off thyristor device, or the second end of the voltage sampling module is connected to the first end of the first open circuit, the first end of the first turn-off circuit, and the gate of the turn-off thyristor device.

2. An overvoltage protection circuit capable of turning off a thyristor device, characterized in that: include: A turn-off circuit, used to realize commutation between the gate and emitter of the turn-off thyristor device according to a control instruction; A first turn-on circuit is used to trigger the turn-off thyristor device to turn on according to a control instruction; a second turn-on circuit, configured to trigger the turn-off thyristor device to turn on when a second voltage between the anode and the gate of the turn-off thyristor device is higher than a first voltage threshold; a voltage sampling module, configured to collect a first voltage between the anode and cathode of the turn-off thyristor device, or to collect a second voltage between the anode and gate of the turn-off thyristor device, and to send a control instruction to the turn-off circuit or the first turn-on circuit when the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold; The shutdown circuit includes a second shutdown circuit and a third shutdown circuit, wherein the first end of the third shutdown circuit is connected to the emitter of the turn-off thyristor device, the second end of the third shutdown circuit is connected to the cathode of the turn-off thyristor device, the first end of the second shutdown circuit is connected to the gate of the turn-off thyristor device, and the second end of the second shutdown circuit is connected to the cathode of the turn-off thyristor device; the first turn-on circuit and the second turn-off circuit are connected in parallel; the first end of the second turn-on circuit is connected to the anode of the turn-off thyristor device, the second end of the second turn-on circuit is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the second turn-off circuit; the first end of the voltage sampling module is connected to the first end of the second turn-on circuit and the anode of the turn-off thyristor device, the second end of the voltage sampling module is connected to the second end of the first turn-on circuit, the second end of the second turn-off circuit, and the cathode of the turn-off thyristor device, or the second end of the voltage sampling module is connected to the first end of the first turn-on circuit, the first end of the second turn-off circuit, and the gate of the turn-off thyristor device.

3. The overvoltage protection circuit of the turn-off thyristor device according to claim 1, characterized in that: The turn-off thyristor device includes an integrated gate-commutated thyristor, a gate-turn-off thyristor or a super gate-turn-off thyristor.

4. The overvoltage protection circuit of the turn-off thyristor device according to claim 2, characterized in that: The turn-off thyristor device includes an emitter-commutated thyristor or an integrated emitter-commutated thyristor.

5. The overvoltage protection circuit of the turn-off thyristor device according to claim 1, characterized in that: The second opening circuit includes a first BOD component; The anode of the first BOD component is connected to the anode of the turn-off thyristor device, and the cathode of the first BOD component is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the first turn-off circuit.

6. The overvoltage protection circuit of the turn-off thyristor device according to claim 1, characterized in that: The second turn-on circuit includes a first thyristor and a voltage regulator assembly; Among them, the cathode of the first thyristor is connected to the first end of the first shutdown circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the first thyristor is connected to the cathode of the voltage regulator tube assembly, the anode of the turn-off thyristor device, and the first end of the voltage sampling module; and the anode of the voltage regulator tube assembly is connected to the gate of the first thyristor.

7. The overvoltage protection circuit of the turn-off thyristor device according to claim 1, characterized in that: The second opening circuit includes a first valve group to an Nth valve group, where N is a positive integer greater than 1, and each valve group includes a second BOD component and a voltage-sharing resistor connected in parallel; Among them, the cathode of the second BOD component in the first valve group is connected to the first end of the first shutdown circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the second BOD component in the first valve group is connected to the cathode of the second BOD component in the second valve group; the anode of the second BOD component in the N-1 valve group is connected to the cathode of the second BOD component in the N valve group; the anode of the second BOD component in the N valve group is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module.

8. The overvoltage protection circuit of the turn-off thyristor device according to claim 1, characterized in that: The second turn-on circuit includes a third BOD component and a current-limiting resistor connected in series.

9. The overvoltage protection circuit of the turn-off thyristor device according to claim 8, characterized in that: The cathode of the third BOD component is connected to the first end of the first turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the third BOD component is connected to the first end of the current limiting resistor; the second end of the current limiting resistor is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module; Alternatively, the anode of the third BOD component is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module, the cathode of the third BOD component is connected to the second end of the current limiting resistor, and the first end of the current limiting resistor is connected to the first end of the first turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit.

10. The overvoltage protection circuit of the turn-off thyristor device according to claim 2, characterized in that: The second opening circuit includes a first BOD component; The anode of the first BOD component is connected to the anode of the turn-off thyristor device, and the cathode of the first BOD component is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the second turn-off circuit.

11. The overvoltage protection circuit of a turn-off thyristor device according to claim 2, characterized in that: The second turn-on circuit includes a first thyristor and a voltage regulator assembly; Among them, the cathode of the first thyristor is connected to the first end of the second shutdown circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the first thyristor is connected to the cathode of the voltage regulator tube assembly, the anode of the turn-off thyristor device, and the first end of the voltage sampling module; and the anode of the voltage regulator tube assembly is connected to the gate of the first thyristor.

12. The overvoltage protection circuit of the turn-off thyristor device according to claim 2, characterized in that: The second opening circuit includes a first valve group to an Nth valve group, where N is a positive integer greater than 1, and each valve group includes a second BOD component and a voltage-sharing resistor connected in parallel; Among them, the cathode of the second BOD component in the first valve group is connected to the first end of the second shutdown circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the second BOD component in the first valve group is connected to the cathode of the second BOD component in the second valve group; the anode of the second BOD component in the N-1 valve group is connected to the cathode of the second BOD component in the N valve group; the anode of the second BOD component in the N valve group is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module.

13. The overvoltage protection circuit of the turn-off thyristor device according to claim 2, characterized in that: The second turn-on circuit includes a third BOD component and a current-limiting resistor connected in series.

14. The overvoltage protection circuit of a turn-off thyristor device according to claim 13, characterized in that: The cathode of the third BOD component is connected to the first end of the second shutdown circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit; the anode of the third BOD component is connected to the first end of the current limiting resistor; the second end of the current limiting resistor is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module; Alternatively, the anode of the third BOD component is connected to the anode of the turn-off thyristor device and the first end of the voltage sampling module, the cathode of the third BOD component is connected to the second end of the current limiting resistor, and the first end of the current limiting resistor is connected to the first end of the second turn-off circuit, the gate of the turn-off thyristor device, and the first end of the first turn-on circuit.

15. The overvoltage protection circuit of a turn-off thyristor device according to any one of claims 1 to 14, characterized in that: The first voltage threshold is lower than the anode breakdown voltage threshold of the turn-off thyristor device, and the second voltage threshold and the third voltage threshold are both lower than the first voltage threshold.

16. The overvoltage protection circuit of a turn-off thyristor device according to claim 5 or 10, characterized in that: The first BOD component breakdown voltage is equal to a first voltage threshold.

17. The overvoltage protection circuit of a turn-off thyristor device according to claim 6 or 11, characterized in that: The overall breakdown voltage of the voltage regulator assembly is equal to the first voltage threshold.

18. The overvoltage protection circuit of a turn-off thyristor device according to claim 7 or 12, characterized in that: The resistance of the voltage balancing resistor is proportional to the breakdown voltage of the second BOD component, and the sum of the breakdown voltages of the second BOD components in the first valve group to the Nth valve group is equal to the first voltage threshold.

19. The overvoltage protection circuit of a turn-off thyristor device according to claim 8 or 13, characterized in that: The third BOD component breakdown voltage is equal to the first voltage threshold.

20. A method for controlling an overvoltage protection circuit capable of turning off a thyristor device, characterized in that: The following steps are involved: The voltage sampling module collects a first voltage between the anode and cathode of the turn-off thyristor device, or collects a second voltage between the anode and the gate of the turn-off thyristor device, and sends a control instruction to the turn-off circuit and the first turn-on circuit when the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold; The turn-off circuit realizes commutation between the gate and emitter of the turn-off thyristor device according to the control instruction; The first turn-on circuit triggers the turn-off thyristor device to turn on according to the control instruction; a second turn-on circuit, triggering the turn-off thyristor device to turn on when a second voltage between the anode and the gate of the turn-off thyristor device is higher than the first voltage threshold; The turn-off circuit includes a first turn-off circuit; wherein the emitter of the turn-off thyristor device is connected to the cathode, the first end of the first turn-off circuit is connected to the gate of the turn-off thyristor device, and the second end of the first turn-off circuit is connected to the cathode of the turn-off thyristor device; the first turn-on circuit and the first turn-off circuit are connected in parallel; The first end of the second open circuit is connected to the anode of the turn-off thyristor device, and the second end of the second open circuit is connected to the gate of the turn-off thyristor device, the first end of the first open circuit, and the first end of the first turn-off circuit; the first end of the voltage sampling module is connected to the first end of the second open circuit and the anode of the turn-off thyristor device, and the second end of the voltage sampling module is connected to the second end of the first open circuit, the second end of the first turn-off circuit, and the cathode of the turn-off thyristor device, or the second end of the voltage sampling module is connected to the first end of the first open circuit, the first end of the first turn-off circuit, and the gate of the turn-off thyristor device.

21. A method for controlling an overvoltage protection circuit capable of turning off a thyristor device, characterized in that: The following steps are involved: The voltage sampling module collects a first voltage between the anode and cathode of the turn-off thyristor device, or collects a second voltage between the anode and the gate of the turn-off thyristor device, and sends a control instruction to the turn-off circuit and the first turn-on circuit when the first voltage is higher than the second voltage threshold or the second voltage is higher than the third voltage threshold; The turn-off circuit realizes commutation between the gate and emitter of the turn-off thyristor device according to the control instruction; The first turn-on circuit triggers the turn-off thyristor device to turn on according to the control instruction; a second turn-on circuit, triggering the turn-off thyristor device to turn on when a second voltage between the anode and the gate of the turn-off thyristor device is higher than the first voltage threshold; The shutdown circuit includes a second shutdown circuit and a third shutdown circuit, wherein the first end of the third shutdown circuit is connected to the emitter of the turn-off thyristor device, the second end of the third shutdown circuit is connected to the cathode of the turn-off thyristor device, the first end of the second shutdown circuit is connected to the gate of the turn-off thyristor device, and the second end of the second shutdown circuit is connected to the cathode of the turn-off thyristor device; the first turn-on circuit and the second turn-off circuit are connected in parallel; the first end of the second turn-on circuit is connected to the anode of the turn-off thyristor device, the second end of the second turn-on circuit is connected to the gate of the turn-off thyristor device, the first end of the first turn-on circuit, and the first end of the second turn-off circuit; the first end of the voltage sampling module is connected to the first end of the second turn-on circuit and the anode of the turn-off thyristor device, the second end of the voltage sampling module is connected to the second end of the first turn-on circuit, the second end of the second turn-off circuit, and the cathode of the turn-off thyristor device, or the second end of the voltage sampling module is connected to the first end of the first turn-on circuit, the first end of the second turn-off circuit, and the gate of the turn-off thyristor device.

22. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 20, characterized in that: The turn-off thyristor device includes an integrated gate-commutated thyristor, a gate-turn-off thyristor or a super gate-turn-off thyristor.

23. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 21, characterized in that: The turn-off thyristor device includes an emitter-commutated thyristor or an integrated emitter-commutated thyristor.

24. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 22, characterized in that: The control method of the overvoltage protection circuit is used in the following working conditions: In the first working condition, the first shut-off circuit, the first open circuit, and the voltage sampling module are all energized; In the second working condition, the first shut-off circuit is not energized, and the first open circuit and the voltage sampling module are energized; In the third operating condition, the first off circuit and the first on circuit are not energized, and the voltage sampling module is energized; In the fourth operating condition, the first shutdown circuit, the first open circuit, and the voltage sampling module are all de-energized.

25. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 24, characterized in that: In the first operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the first shutdown circuit is controlled to remove the reverse voltage, and at the same time the voltage sampling module controls the first turn-on circuit to inject a current trigger signal into the gate of the turn-off thyristor device, after which the turn-off thyristor device is triggered to turn on, and the second voltage between the anode and the gate of the turn-off thyristor device does not exceed the first voltage threshold, and the second turn-on circuit does not operate.

26. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 24, characterized in that: In the second operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the first shutdown circuit does not operate; at the same time, the voltage sampling module controls the first opening circuit to inject a current trigger signal into the gate of the turn-off thyristor device, and then the turn-off thyristor device is triggered to turn on. The second voltage between the anode and the gate of the turn-off thyristor device does not exceed the first voltage threshold, and the second opening circuit does not operate.

27. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 24, characterized in that: In the third operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, neither the first shutdown circuit nor the first opening circuit operates. At this time, the first shutdown circuit cannot apply reverse voltage; when the second voltage exceeds the first voltage threshold, the second opening circuit operates and generates a current trigger signal, triggering the turn-off thyristor device to turn on.

28. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 24, characterized in that: In the fourth operating condition, the first shutdown circuit, the first opening circuit, and the voltage sampling module are all inactive. When the second voltage exceeds the first voltage threshold, the second opening circuit is activated and generates a current trigger signal, triggering the turn-off thyristor device to turn on.

29. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 23, characterized in that: The control method of the overvoltage protection circuit is used in the following working conditions: In the fifth working condition, the first on-circuit, the voltage sampling module, the second off-circuit, and the third off-circuit are all energized; In the sixth operating condition, the first open circuit is not energized, and the voltage sampling module, the second shut-off circuit, and the third shut-off circuit are energized; In the seventh working condition, the voltage sampling module is energized, and the first open circuit, the second shut-off circuit, and the third shut-off circuit are not energized; In the eighth operating condition, the first open circuit, the voltage sampling module, the second shut-off circuit, and the third shut-off circuit are all de-energized.

30. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 29, characterized in that: In the fifth operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third threshold, the second shutdown circuit is controlled to be disconnected, the third shutdown circuit is controlled to be closed, and at the same time, the first turn-on circuit is controlled to inject a current trigger signal into the gate of the turn-off thyristor device, after which the turn-off thyristor device is triggered to turn on, the second voltage does not exceed the first voltage threshold, and the second turn-on circuit does not operate.

31. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 29, characterized in that: In the sixth operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the second shutdown circuit is controlled to be disconnected, the third shutdown circuit is controlled to be closed, and the first opening circuit does not operate. When the second voltage exceeds the first voltage threshold, the second opening circuit operates and generates a current trigger signal, and then the thyristor device can be turned off to trigger the opening.

32. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 29, characterized in that: In the seventh operating condition, when the voltage sampling module detects that the first voltage is higher than the second voltage threshold, or detects that the second voltage is higher than the third voltage threshold, the second shutdown circuit, the third shutdown circuit and the first opening circuit do not operate; when the second voltage exceeds the first voltage threshold, the second opening circuit operates and generates a current trigger signal, and then the thyristor device can be turned off to trigger the opening.

33. The control method of the overvoltage protection circuit of the turn-off thyristor device according to claim 29, characterized in that: In the eighth operating condition, the first turn-on circuit, the voltage sampling module, the second turn-off circuit, and the third turn-off circuit are all inactive. When the second voltage exceeds the first voltage threshold, the second turn-on circuit is activated and generates a current trigger signal, which can then turn off the thyristor device to trigger the turn-on.

34. The method for controlling an overvoltage protection circuit of a turn-off thyristor device according to any one of claims 29 to 33, wherein: The second shutoff circuit maintains a normally closed state when power is lost; the third shutoff circuit maintains a normally open state when power is lost; or the third shutoff circuit can be turned into an open state when it is subjected to a positive voltage when power is lost.

35. The method for controlling an overvoltage protection circuit of a turn-off thyristor device according to any one of claims 20 to 33, characterized in that: The first voltage threshold is lower than the anode breakdown voltage threshold of the turn-off thyristor device, and the second voltage threshold and the third voltage threshold are both lower than the first voltage threshold.

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