Gate-commutated thyristor fault detection circuit and method thereof

Abstract

The application provides a gate-commutated thyristor fault detection circuit and a method thereof. The detection circuit comprises an IGCT device and a first diode connected in antiparallel with the IGCT device, characterized in that a turn-off detection unit is arranged between the anode and the gate of the IGCT device, a driving unit is arranged between the gate and the cathode of the IGCT device, and the turn-off detection unit is connected with the driving unit. The voltage between the anode and the gate of the IGCT device is detected to determine the turn-off fault of the IGCT device. The detection circuit has the advantages of simplicity, high sensitivity, good real-time performance, and the like, can effectively detect the device fault, and realizes the protection of the equipment. Meanwhile, the detection method can accurately determine the on-flow state of the antiparallel diode, and improves the detection effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to a gate-commutated thyristor fault detection circuit and a method thereof. BACKGROUND

[0002] When a gate-commutated thyristor (IGCT) device fails, it is difficult to turn off the excessive fault current because it does not have a desaturation effect. Therefore, in the scenario of a voltage source converter, it is necessary to quickly detect the turn-off fault and timely lock the device to avoid the spread of the fault. At present, there are gate-cathode voltage detection, anode-cathode voltage detection and other methods, and because the detection is not timely and it is difficult to judge the on-state of the anti-parallel diode, the detection effect is not ideal. SUMMARY

[0003] To solve the above problems, the application provides a gate-commutated thyristor fault detection circuit, which comprises an IGCT device and a first diode connected in anti-parallel with the IGCT device, a turn-off detection unit arranged between the anode and the gate of the IGCT device, a driving unit arranged between the gate and the cathode of the IGCT device, and the turn-off detection unit is connected with the driving unit.

[0004] Further, the turn-off detection unit comprises a voltage dividing circuit and a comparison circuit, the voltage dividing circuit is connected with the anode and the gate of the IGCT device, and the comparison circuit is connected with the driving unit and the voltage dividing circuit.

[0005] Further, the voltage dividing circuit comprises a first resistor and a voltage stabilizing tube, the comparison circuit comprises a comparator, one end of the comparator is connected between the first resistor and the voltage stabilizing tube, and the other end of the comparator is connected with the driving unit.

[0006] Further, the voltage dividing circuit comprises a first resistor and a second resistor, the comparison circuit comprises a comparator, one end of the comparator is connected between the first resistor and the second resistor, and the other end of the comparator is connected with the driving unit.

[0007] Further, the first resistor is determined according to the highest bus voltage and the rated power;

[0008] The stable voltage of the voltage stabilizing tube is greater than the anode-gate voltage after turn-off failure and less than the turn-off voltage applied by the driving unit to the gate-cathode.

[0009] Further, the second resistor is determined according to the highest bus voltage, the resistance value of the first resistor and the accuracy of the detection circuit.

[0010] Further, the detection circuit further comprises an inductor, a first capacitor, a second capacitor, a resistor, a second diode, wherein,

[0011] One end of the second capacitor is connected with a negative electrode of the second diode, the IGCT device is connected with a positive electrode of the second diode and the other end of the second capacitor, one end of the first capacitor is connected with one end of the inductor and the resistor respectively, the other end of the inductor and the other end of the resistor are connected with the positive electrode and the negative electrode of the second diode respectively, and the other end of the first capacitor is connected with the other end of the second capacitor.

[0012] The application further provides a fault detection method of the gate-commutated thyristor, which judges whether the turn-off is faulty by detecting whether the anode-gate voltage is less than a threshold after the IGCT device is turned off, and judges that the turn-off is faulty if the anode-gate voltage detected by the turn-off detection unit is less than the threshold.

[0013] Further, the threshold is greater than the anode-gate voltage after the turn-off fails and less than the turn-off voltage applied to the gate-cathode by the driving unit.

[0014] The gate-commutated thyristor fault detection circuit and the method thereof have the advantages of simple detection circuit, high sensitivity, good real-time performance, etc., can effectively detect the device fault and realize the protection of the equipment, and the detection method can also accurately judge the current flow state of the reverse parallel diode and improve the detection effect.

[0015] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the following description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by means of the structures particularly pointed out in the description, the claims and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0017] Figure 1 The figure shows the application of the fault detection circuit in the embodiment of the present application to the circuit topology structure schematic diagram;

[0018] Figure 2 The figure shows the structure schematic diagram of the turn-off detection unit (first resistor, second resistor) in the embodiment of the present application;

[0019] Figure 3A schematic diagram of the shutdown detection unit (first resistor, Zener diode) in an embodiment of the present invention is shown;

[0020] Figure 4 A schematic flowchart of the fault detection method in an embodiment of the present invention is shown. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention proposes a fault detection circuit for gate-commutated thyristor devices based on anode-gate voltage detection. Figure 1 A schematic diagram of the applicable circuit topology of the fault detection circuit in an embodiment of the present invention is shown. Figure 1 The detection circuit includes: IGCT devices (T1, T2) and first diodes (D1, D2) connected in reverse parallel with the IGCT devices. A turn-off detection unit is disposed between the anode and gate of the IGCT devices, and a driving unit is disposed between the gate and cathode of the IGCT devices. The turn-off detection unit is connected to the driving unit. The detection circuit also includes an inductor L. s First capacitor, second capacitor C s Resistance R s Second diode D s Among them, the second capacitor C s One end is connected to the second diode D s With the negative terminal connected, the IGCT devices (T1, T2) are connected to the second diode D. s Positive electrode and second capacitor C s At the other end, one end of the first capacitor is connected to the inductor L. s and resistance R s One end, inductor L s The other end is connected to resistor R s The other end is connected to the second diode D. s The positive and negative terminals of the first capacitor are connected, and the other end of the first capacitor is connected to the second capacitor C. s The other end is connected.

[0023] In this embodiment of the invention, the shutdown behavior of T1 is taken as an example:

[0024] Before turn-off, the current path of the IGCT is as follows: the current flows from below the circuit without passing through the IGCT device and the second capacitor C. s, the current flowing out of the first capacitor passes through the inductor L s , IGCT device, the current path does not change after the failure of the turn-off; the current path is: the current flows out from the bottom of the circuit through the first diode D2 below; the current path of the anti-parallel diode before turn-off is: the current flows out from the top of the circuit through the first diode D1, and the current flowing out of the first diode D1 passes through the inductor L s , the first capacitor directly flows out, and the current path does not change after the turn-off; before the turn-off, the IGCT device or the anti-parallel diode is in conduction, and the current direction of the external circuit determines the periodic repetition in the device operation.

[0025] Since the turn-off energy of the IGCT device is large when it is in conduction, the possibility of turn-off failure is significantly higher, so the turn-off failure of this state is detected, and specifically, the theoretical principle of fault detection is:

[0026] The IGCT device is in the on state before turn-off, at this time, if the IGCT is in conduction, the current is transferred to D2 after normal turn-off, the IGCT device bears the DC bus voltage, and the anode-cathode voltage is about equal to the DC bus voltage, usually hundreds of V to kV level;

[0027] When the IGCT is in the on state before turn-off, but the anti-parallel diode of the IGCT is in conduction due to the opposite current direction of the external loop, the anti-parallel diode of the IGCT is still in conduction after normal turn-off, and the voltage across the two is very low, at this time the anode-cathode voltage of the IGCT device is almost equal. Because the drive circuit applies a reverse voltage (typical value -20V) to the gate-cathode under the turn-off state, the voltage between the anode and the gate is 20V at this time;

[0028] When the turn-off fails, the pressure junction J2 (used to withstand voltage under the turn-off state) of the IGCT device is broken down, at this time the anode-gate is in a short circuit state, and the voltage is very low (less than 5V).

[0029] By setting a circuit, whether the anode-gate voltage is less than a certain threshold value (the threshold value is greater than the anode-gate voltage after the turn-off failure (for example, 5V), and less than the turn-off voltage applied by the drive to the gate-cathode (for example, 20V)) is detected after the IGCT turns off, to determine whether the turn-off fails. If the turn-off fails, the controller is notified of the fault and the device is shut down.

[0030] The turn-off detection unit includes a voltage dividing circuit and a comparison circuit, the voltage dividing circuit is connected to the anode-gate of the IGCT device, and the comparison circuit is connected to the drive unit and the voltage dividing circuit.

[0031] Specifically, the voltage dividing circuit includes a first resistor and a voltage stabilizing tube, the comparison circuit includes a comparator, one end of the comparator is connected between the first resistor and the voltage stabilizing tube, and the other end of the comparator is connected to the driving unit; the voltage dividing circuit includes a first resistor and a second resistor, the comparison circuit includes a comparator, one end of the comparator is connected between the first resistor and the second resistor, and the other end of the comparator is connected to the driving unit.

[0032] The voltage dividing circuit of the turn-off detection unit in the embodiment of the application can be a first resistor and a second resistor voltage dividing circuit, or a first resistor and a voltage stabilizing tube voltage dividing circuit, Figure 2 The structure diagram of the turn-off detection unit (first resistor and second resistor) in the embodiment of the application is shown, Figure 2 In the structure, the driving unit is connected to the gate-cathode, the first resistor and the second resistor are connected in series between the anode-gate, one end of the comparator is connected between the first resistor and the second resistor, the other end of the comparator is connected to the driving unit, and the reference voltage is connected to the comparator.

[0033] Figure 3 The structure diagram of the turn-off detection unit (first resistor and voltage stabilizing tube) in the embodiment of the application is shown, Figure 3 In the structure, the driving unit is connected to the gate-cathode, the first resistor and the voltage stabilizing tube are connected in series between the anode-gate, one end of the comparator is connected between the first resistor and the voltage stabilizing tube, the other end of the comparator is connected to the driving unit, and the reference voltage is connected to the comparator.

[0034] The first resistor R 第一 The resistance value is determined according to the rated power and the highest bus voltage, wherein the highest bus voltage is equal to the repeatable peak blocking voltage of the IGCT device, and the turn-off voltage (U gk ) applied to the gate-cathode should be sufficient to be detected (for example, greater than 0.1 uA), and the loss power of the resistor should not be too large (for example, not more than 50 W) when the highest bus voltage is applied, and the resistance value is 1 kΩ-200 MΩ; the withstand voltage should be not less than the highest bus voltage (U DC ), and the rated power should be not less than the loss power of the resistor when the highest bus voltage is applied:

[0035] R 第一 <U gk / 0.1uA;

[0036] R 第一 >U DC 2 / 50W;

[0037] U R第一 >U DC ;

[0038] PR第一 >U DC 2 / R 第一

[0039] second resistance R 第二 is determined according to the highest bus voltage, the first resistance value and the accuracy of the detection circuit, wherein the accuracy of the detection circuit is determined according to the accuracy of the comparator chip and the circuit interference level. Generally, the detection accuracy is above mV level, when the highest bus voltage is applied to the anode, the voltage division thereof should not be higher than the insulation level U drivemax of the driving circuit (for example, not more than 200V), and when the off voltage U gk is applied to the gate-cathode, the voltage division thereof should not be lower than the lowest detection voltage U testmin of the detection circuit (for example, 1mV);

[0040] R 第二 <R 第一 *U drivemax / U DC

[0041] R 第二 >R 第一 *U testmin / U gk

[0042] The stable voltage U t of the voltage stabilizing tube should be greater than the anode-gate voltage after off failure (for example, 5V) and less than the off voltage applied to the gate-cathode by the driving unit (for example, 20V).

[0043] 5V<U t <U gk

[0044] The embodiment of the present application also provides a gate-commutated thyristor fault detection method, Figure 4 a flowchart of the fault detection method in the embodiment of the present application is shown, Figure 4 In the method, the off state is judged, if the off state is reached, the voltage between the anode and the gate of the IGCT device is detected, if the voltage is higher than the threshold, the off is successful; if the voltage is lower than the threshold, the off is failed, the off failure is reported, and the detection is completed.

[0045] Specifically, whether the off is failed is judged by detecting whether the anode-gate voltage is less than the threshold after the off of the IGCT device, if the anode-gate voltage detected by the off detection unit is less than the threshold, it is judged that the off is failed; the threshold is greater than the anode-gate voltage after the off failure and less than the off voltage applied to the gate-cathode by the driving unit.

[0046] Specifically, the threshold is greater than the anode-gate voltage after the turn-off failure (for example, 5V) and less than the turn-off voltage applied to the gate-cathode (for example, 20V).

[0047] The gate-commutated thyristor fault detection circuit and the method thereof can effectively detect the device fault and protect the equipment by detecting the voltage between the anode and the gate of the IGCT device to determine the turn-off failure of the IGCT device, and the detection method can also accurately determine the conduction state of the reverse parallel diode, thereby improving the detection effect.

[0048] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A gate commutated thyristor fault detection circuit, the detection circuit comprising: The IGCT device and the first diode connected in reverse parallel with the IGCT device are characterized in that, A turn-off detection unit is provided between the anode and the gate of the IGCT device, and a driving unit is provided between the gate and the cathode of the IGCT device. The turn-off detection unit is connected to the driving unit. The shutdown detection unit includes a voltage divider circuit and a comparator circuit. The voltage divider circuit is connected to the anode-gate of the IGCT device, and the comparator circuit is connected to the drive unit and the voltage divider circuit. The voltage divider circuit includes a first resistor and a Zener diode, and the comparator circuit includes a comparator, one end of which is connected between the first resistor and the Zener diode, and the other end of which is connected to the driving unit. The stable voltage of the Zener diode is greater than the anode-gate voltage after a turn-off failure, but less than the turn-off voltage applied to the gate-cathode by the drive unit. The detection circuit further includes an inductor, a first capacitor, a second capacitor, a resistor, and a second diode, wherein... One end of the second capacitor is connected to the negative terminal of the second diode. The IGCT device is connected to the positive terminal of the second diode and the other end of the second capacitor. One end of the first capacitor is connected to one end of the inductor and the resistor respectively. The other end of the inductor and the other end of the resistor are connected to the positive and negative terminals of the second diode respectively. The other end of the first capacitor is connected to the other end of the second capacitor. The shutdown fault is determined by detecting whether the anode-gate voltage is less than a threshold after the IGCT device is turned off. If the anode-gate voltage detected by the shutdown detection unit is less than the threshold, the shutdown fault is determined to have occurred. The threshold is greater than the anode-gate voltage after a shutdown failure, but less than the shutdown voltage applied by the drive unit to the gate-cathode.

2. The gate commutated thyristor fault detection circuit according to claim 1, characterized in that, The voltage divider circuit includes a first resistor and a second resistor, and the comparator circuit includes a comparator, one end of which is connected between the first resistor and the second resistor, and the other end of which is connected to the driving unit.

3. The gate commutated thyristor fault detection circuit according to claim 2, characterized in that, The first resistor is determined based on the highest bus voltage and rated power.

4. The gate commutated thyristor fault detection circuit according to claim 2, characterized in that, The second resistor is determined based on the highest bus voltage, the value of the first resistor, and the accuracy of the detection circuit.

5. A method for detecting gate-commutated thyristor faults, characterized in that, Using the detection circuit according to any one of claims 1-4, wherein... The shutdown fault is determined by detecting whether the anode-gate voltage is less than a threshold after the IGCT device is turned off. If the anode-gate voltage detected by the shutdown detection unit is less than the threshold, the shutdown fault is determined to have occurred. The threshold is greater than the anode-gate voltage after a shutdown failure, but less than the shutdown voltage applied by the drive unit to the gate-cathode.

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