IGCT short circuit fault and main circuit operation status monitoring method and monitoring circuit

Abstract

The present invention relates to a monitoring method and a monitoring circuit for IGCT short-circuit fault and main circuit operation status, and its technical characteristics are: connecting a voltage detection circuit to a buffer absorption circuit, detecting a voltage U between a common point of a reactor and an IGCT and a midpoint of a DC bus power supply. AN and U BN Waveform, acquisition U AN and U BN The peak voltage and peak time are used as characteristic values, and their maximum value V is obtained through continuous acquisition and data sorting. DM The maximum value occurs at T DM , sent to the numerical fitting observer to obtain the estimated value of the current main circuit parameter RC, and the current estimated value of RC is compared with the actual initial value of RC to determine whether the buffer absorption circuit is in a normal state. If there are abnormal reasons such as device aging that cause parameter changes, an alarm prompt is given. The present invention can monitor the operating status of the buffer absorption circuit in real time, reduce the loss caused to customers by abnormal equipment shutdown, and at the same time can accurately give the location of abnormal components, reducing the time required for customers to troubleshoot problems.

Description

Technical Field

[0001] The invention belongs to the field of IGCT fault detection, in particular to an IGCT short-circuit fault and main loop operating state monitoring method and monitoring circuit. Background Art

[0002] The power electronic equipment of the rolling mill main drive system has the characteristics of large capacity, strong overload capacity, and fast dynamic response, and is the core equipment of metallurgical production. The high-power converter based on IGCT is increasingly used in the main drive system of the rolling mill. In the design of IGCT converter, the design of its buffer absorption circuit, the detection and protection of short-circuit faults have always been the hot spots and difficulties in converter design and development. Currently, the IGCT converter products on the market lack detection methods for abnormal conditions of the buffer circuit. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and to propose a method and a monitoring circuit for IGCT short-circuit fault and main circuit operation status, which can timely discover faults and potential fault hazards and prompt processing, reduce the losses caused to customers by abnormal equipment shutdown, and at the same time can more accurately give the location of abnormal components and reduce fault investigation time.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A method for monitoring an IGCT short-circuit fault and a main circuit operating state comprises the following steps:

[0006] Step 1: The voltage acquisition board collects the buffer absorption circuit voltage U in real time AN and U BN Data waveform, and processed according to the on-off state of IGCT, if IGCT is on, go to step 2, otherwise go to step 3;

[0007] Step 2: When the IGCT is turned on, detect the voltage U AN and U BN Data waveform U AN and U BN to zero time, and according to U AN and U BN The time from 0 to zero determines whether a short-circuit fault occurs;

[0008] Step 3: When IGCT is turned off, intercept U AN and U BN The data waveform triggers the shutdown signal within 40us. AN and U BNThe waveform data is obtained, and the peak voltage and peak time are extracted as characteristic values, which are sent to the numerical fitting observer in the control board to calculate the estimated values ​​of the R value and C value of the current buffer absorption circuit; the estimated values ​​of the R value and C value are compared with the saved initial values ​​of the R value and C value of the buffer absorption circuit to determine the operating status of the buffer absorption circuit.

[0009] Moreover, the method for determining whether a short-circuit through fault occurs in step 2 is as follows:

[0010] When the load current I L >0, and the switch state changes to V3 off and V1 on, detect U AN ≈0 time, if it exceeds the threshold, it is considered that a straight-through fault occurs;

[0011] When the load current I L <0, and the switch state changes to V2 off and V4 on, detect U BN ≈0. If the time exceeds the threshold, it is considered that a straight-through failure occurs.

[0012] Furthermore, the step 3 comprises the following steps:

[0013] Step 3.1, set the counter to 0;

[0014] Step 3.2, generating a shutdown signal;

[0015] Step 3.3: The voltage acquisition board continuously collects U AN and U BN Data waveform;

[0016] Step 3.4: Determine whether the duration exceeds 40us. If so, proceed to step 3.5; otherwise, return to step 3.3.

[0017] Step 3.5: Find U AN or U BN The maximum value of the data V DM And its corresponding time position T DM ;

[0018] Step 3.6: V obtained in step 3.5 DM and T DM The actual value of is input into the numerical fitting observer in the control board card, and the estimated values ​​of R value and C value of the buffer absorption circuit are calculated. The estimated values ​​of R value and C value of the buffer absorption circuit are compared with the initial values ​​of R value and C value set for the buffer absorption circuit. If they are within the range of the initial values, step 3.7 is performed, otherwise step 3.8 is performed;

[0019] Step 3.7, the counter is reset to zero, judging that the buffer absorption circuit is operating normally and the monitoring is ended;

[0020] Step 3.8, determine that the buffer absorption circuit is operating abnormally, and the counter value is +1; determine whether the counter value is greater than or equal to 3. If the counter value is greater than or equal to 3, proceed to step 3.9, otherwise return to step 3.2;

[0021] Step 3.9: If the initial value range of R and C set in the buffer absorption circuit is exceeded three times in a row, a normal shutdown or alarm is requested, and this monitoring ends.

[0022] An IGCT short-circuit fault and main circuit operation status monitoring circuit includes a voltage acquisition board and a control board. The voltage acquisition board is connected to a buffer absorption circuit to collect a positive half group DC voltage U of the buffer absorption circuit. AN And the negative half group DC voltage U BN And input to the control board, the control board monitors the IGCT short circuit fault and the main circuit operation status.

[0023] Moreover, the control board includes a numerical fitting observer, which includes a numerical normalization module, a nonlinear fitting module, a linear fitting module and a numerical denormalization module connected in sequence. The input end of the numerical normalization module is connected to the voltage acquisition board, and the numerical denormalization module outputs the estimated values ​​of the R value and C value of the buffer absorption loop.

[0024] Moreover, the specific structure of the numerical normalization module is the u+c1 module, k1 module and u-1 module connected in sequence, the specific structure of the nonlinear fitting module is the added w1 module and b1 module input into the hyperbolic function module, the specific structure of the linear fitting module is the w1 module and b1 module input into the straight line function module, and the specific structure of the numerical denormalization module is the u+c2 module, k2 module and u+1 module connected in sequence, wherein c1 and k1 are numerical normalization coefficient matrices, w1 and b1 are nonlinear fitting coefficient matrices, w2 and b2 are linear fitting coefficient matrices, c2 and k2 are numerical denormalization coefficient matrices, and c1, k1, w1, b1, w2, b2, c2 and k2 are obtained by training through neural network input data and target data.

[0025] Moreover, the relationship between the input data and the output data is:

[0026]

[0027]

[0028] Q = arctan(2RC*w)

[0029]

[0030]

[0031] Among them, w is the intermediate calculation variable, L is the inductance of the buffer absorption loop, C is the capacitance of the buffer absorption loop, R is the resistance of the buffer absorption loop, o is the intermediate calculation variable, Q is the intermediate calculation variable, I L is the load current, V DM is the peak voltage, T DM is the peak time.

[0032] The advantages and positive effects of the present invention are:

[0033] 1. The present invention connects the monitoring circuit between the common point of the reactor and the IGCT in the buffer absorption circuit and the midpoint of the DC bus power supply, and records the voltage U AN and U BN Data waveform, according to U AN and U BN The data waveform obtains the peak voltage and peak time as characteristic values, that is, the maximum voltage V DM The maximum value occurs at T DM , sent to the numerical fitting observer to obtain the estimated value of the current main circuit parameter RC, and the estimated value is compared with the actual initial value of RC to determine whether the buffer absorption circuit is in a normal state. If the parameter changes due to abnormal reasons such as device aging, cold soldering, heating, etc., an alarm prompt is given. The present invention can monitor the operating status of the buffer absorption circuit in real time. When the capacitor in the buffer absorption circuit ages and causes the capacitance to decrease, or the resistance value changes significantly due to long-term operation or burning, it can be discovered in time and a prompt can be given to reduce the loss caused to customers by abnormal equipment shutdown. At the same time, the location of abnormal components can be given more accurately, reducing the time required for customers to troubleshoot problems.

[0034] 2. The monitoring circuit of the present invention detects the voltage U between the common point of the inductor and the IGCT and the midpoint of the DC bus power supply. AN and U BN Data waveform, can simultaneously detect the switching time, when U AN and U BN The time of zero exceeds the normal commutation time by 1.5 times, which is about 6 to 10 us, and it is determined that the device has a short circuit fault. The protection action time of the present invention is within 10 us, and the protection action can be triggered timely and reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the existing IGCT power circuit, including the schematic diagram of the buffer absorption circuit;

[0036] Figure 2 This is a connection diagram of the monitoring circuit of the present invention;

[0037] Figure 3 This is a schematic diagram of the sampling voltage waveform of the present invention;

[0038] Figure 4 It is a determination flow chart of the present invention;

[0039] Figure 5 This is the principle diagram of the numerical fitting observer of the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to the accompanying drawings.

[0041] The present invention proposes an IGCT short-circuit fault and main circuit operation status monitoring circuit, which performs IGCT short-circuit fault and main circuit operation status monitoring on the existing power main circuit and buffer absorption circuit. Figure 1 As shown, the buffer absorption circuit includes an inductor L1, an inductor L2, a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a diode D8, a switch tube V1, a switch tube V2, a switch tube V3 and a switch tube V4, one end of the inductor L1 is connected to the positive electrode of the AC power supply of the main circuit, the other end of the inductor L1 is connected to the positive electrode of the diode D7, the collector of the switch tube V1 and the negative electrode of the diode D1 respectively, the negative electrode of the diode D7 is connected in series with the capacitor C1, the capacitor C2 and the positive electrode of the diode D8, the negative electrode of the diode D8 is connected to one end of the inductor L2, the emitter of the switch tube V4 and the positive electrode of the diode D4 respectively, the other end of the inductor L2 is connected to the negative electrode of the AC power supply of the main circuit, the resistor R1 is connected in parallel to the inductor L1 and the diode D4. The resistor R2 is connected in parallel to the inductor L2 and the diode D8. The switch tubes V1, V2, V3 and V4 are connected in series in the form of the emitter connecting the collector. The diodes D1, D2, D3 and D4 are connected in series in the form of the positive electrode connecting the negative electrode. The neutral line of the main circuit is respectively connected to the series node of the capacitor C1 and the capacitor C2, the positive electrode of the diode D5 and the negative electrode of the diode D6. The negative electrode of the diode D5 is respectively connected to the series node of the switch tube V1 and the switch tube V2 and the series node of the diode D1 and the diode D2. The positive electrode of the diode D5 is respectively connected to the series node of the switch tube V3 and the switch tube V4 and the series node of the diode D3 and the diode D4. The series node of the switch tube V2 and the switch tube V3 is connected to the series node of the diode D2 and the diode D3 and outputs the load current I L .

[0042] like Figure 2As shown, the IGCT short-circuit fault and main circuit operation status monitoring circuit of the present invention includes a voltage acquisition board and a control board. The innovation of the present invention is that the voltage acquisition board adds a voltage detection function at three specific points of the buffer absorption, that is, the voltage acquisition board is connected to the series node A of the inductor L1 and the diode D7, the series node N of the capacitor C1 and the capacitor C2, and the series node B of the inductor L2 and the diode D8, respectively, to collect the positive half group DC voltage U of the buffer absorption circuit. AN And the negative half group DC voltage U BN , and the positive half group DC voltage U AN And the negative half group DC voltage U BN Input to the control board. The control board includes a numerical fitting observer, which includes a numerical normalization module, a nonlinear fitting module, a linear fitting module and a numerical denormalization module connected in sequence. The input end of the numerical normalization module is connected to the voltage acquisition board, and the numerical denormalization module outputs the estimated values ​​of the R value and C value of the buffer absorption loop.

[0043] like Figure 5 As shown, the specific structure of the numerical normalization module is the u+c1 module, k1 module and u-1 module connected in sequence, the specific structure of the nonlinear fitting module is the added w1 module and b1 module input to the hyperbolic function module, the specific structure of the linear fitting module is the w1 module and b1 module input to the straight line function module, the specific structure of the numerical denormalization module is the u+c2 module, k2 module and u+1 module connected in sequence, wherein c1 and k1 are numerical normalization coefficient matrices, w1 and b1 are nonlinear fitting coefficient matrices, w2 and b2 are linear fitting coefficient matrices, c2 and k2 are numerical denormalization coefficient matrices, c1, k1, w1, b1, w2, b2, c2 and k2 are obtained by inputting input data and target data into the neural network for training, and the input of the u+c1 module is the load current I L , U AN or U BN The maximum value of the data V DM And its corresponding time position T DM , where the load current I L with U AN or U BN The maximum value of the data V DM There is a linear correlation.

[0044] The relationship between input data and output data is:

[0045]

[0046]

[0047] Q = arctan(2RC*w)

[0048]

[0049]

[0050] Among them, L is the inductance of the buffer absorption loop, C is the capacitance of the buffer absorption loop, R is the resistance of the buffer absorption loop, w is the intermediate calculation variable, o is the intermediate calculation variable, Q is the intermediate calculation variable, I L is the load current, V DM is the peak voltage, T DM is the peak time.

[0051] The monitoring principle of the present invention is:

[0052] like Figure 2 As shown in the figure, due to the presence of inductors L1 and L2 in the di / dt snubber circuit, the current change rate of the fast recovery diode at the switching moment is limited. After the IGCT is turned off, the current on the snubber circuit inductor Li will be charged to the snubber capacitor Ci (i = 1 or 2) through the diode, causing a temporary voltage rise at the turn-off moment. Figure 3 As shown, the voltage drop of the power device at this stage has two peak voltages V dsp and V DM The first peak voltage V dsp Mainly caused by the stray inductance of the copper busbar. The second peak voltage V DM It is mainly affected by the inductance, capacitance and resistance parameters of the buffer absorption loop.

[0053] The present invention also provides a method for monitoring an IGCT short circuit fault and a main circuit operation status, comprising the following steps:

[0054] Step 1: The voltage acquisition board collects the buffer absorption circuit voltage U in real time AN and U BN Data waveform, and determine whether IGCT is turned on or off, if IGCT is turned on, proceed to step 2, otherwise proceed to step 3.

[0055] Step 2: When the IGCT is turned on, detect the voltage U AN and U BN Data waveform U AN and U BN is zero time, and according to U AN and U BN The time when it reaches zero determines whether a short-circuit fault occurs.

[0056] The detection principle of this step is: when the normal IGCT is turned on, due to the existence of the buffer absorption circuit absorption inductance L, its current change rate di / dt = U dc / L, where Udc is the positive and negative half-group DC voltage; when the load current I L >0, when the load current flows outward, if the switch tube state changes to switch tube V3 off and switch tube V1 on, the output current will be commutated from diode D5 to switch tube V1, and the duration of this process is t≈I L *L / U dc , during the duration of the process U AN ≈0, usually between 0 and 6us. If a short-circuit fault occurs, the bridge arm of the IGCT is short-circuited, U AN Keep it at 0.

[0057] Therefore, the determination method for this step is:

[0058] When the load current I L >0 (i.e. the load current flows outward), and the switch tube state changes to switch tube V3 off and switch tube V1 on, detect U AN If the time exceeds 0 to 6us (this value is related to the circuit parameters), a straight-through fault is considered to have occurred.

[0059] When the load current I L <0 (i.e., the load current flows outward), and the switch tube state changes to switch tube V2 off and switch tube V4 on, detect U BN If the time exceeds 0 to 6us (this value is related to the circuit parameters), a straight-through fault is considered to have occurred.

[0060] Step 3: When IGCT is turned off, intercept U AN and U BN The data waveform triggers the shutdown signal within 40us. AN and U BN The waveform data is obtained, and the peak voltage and peak time are extracted as characteristic values, which are sent to the numerical fitting observer in the control board to calculate the estimated values ​​of the R value and C value of the current buffer absorption circuit; the estimated values ​​of the R value and C value are compared with the initial value range of the R value and C value set for the buffer absorption circuit to determine the operating status of the buffer absorption circuit.

[0061] like Figure 4 As shown, the process of this step is:

[0062] Step 3.1, set the counter to 0;

[0063] Step 3.2, generating a shutdown signal;

[0064] Step 3.3: The detection circuit continuously collects U AN and U BN Data waveform;

[0065] Step 3.4: Determine whether the duration exceeds 40us.

[0066] Step 3.5, find U AN or U BN Data maximum value V DM And its corresponding time position T DM ;

[0067] Step 3.6: V obtained in step 3.5 DM and T DM The actual value of is input into the numerical fitting observer in the control board card, and the estimated values ​​of the R value and C value of the buffer absorption circuit are calculated. The estimated values ​​of the R value and C value of the buffer absorption circuit are compared with the initial value range of the R value and C value set for the buffer absorption circuit. If they are within a certain range of the initial values ​​(for example, 0.95 to 1.05), step 3.7 is performed, otherwise step 3.8 is performed;

[0068] Step 3.7, the counter is reset to zero, judging that the buffer absorption circuit is operating normally and the monitoring is ended;

[0069] Step 3.8, determine that the buffer absorption circuit is operating abnormally, and at the same time the counter value +1, determine whether the counter value is greater than or equal to 3, if the counter value is greater than or equal to 3, proceed to step 3.9, otherwise return to step 3.2;

[0070] Step 3.9: If the initial value range of R and C set in the buffer absorption circuit is exceeded three times in a row, a normal shutdown or alarm is requested, and this monitoring ends.

[0071] According to the above invention content, calculation is performed for a certain circuit.

[0072] Circuit load current I L =4000A, inductance L = 4uh

[0073] like Figure 4 The control block diagram shown in the figure, the specific values ​​of the numerical fitting observer are:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] When the capacitance C=12.5uF, the resistance R=0.9Ω, refer to the above theoretical calculation

[0082]

[0083]

[0084] Q = arctan(2RC*w)

[0085]

[0086]

[0087] It can be seen that the corresponding theoretical peak voltage V DM =1495.4V, peak time T DM =9.318us, substituting the peak voltage and peak time into the numerical fitting observer, the estimated values ​​of the circuit parameters RC are 0.9257Ω and 12.4uF, which are very close to the actual values ​​of 0.9Ω and 12.5uF.

[0088] IGCT device short circuit detection:

[0089] First, calculate the IGCT theoretical commutation time t = |I L *L / U dc |

[0090] When V1 or V3 is turned on, U AN Amplitude less than 0.1*U dc The duration is T. If T<1.5*t, the device is normal, otherwise it is judged as abnormal.

[0091] When V2 or V4 is turned on, U BN Amplitude less than 0.1*U dc Duration T, if T<1.5*t, the system is normal, otherwise it is judged as abnormal state.

[0092] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for monitoring IGCT short-circuit fault and main circuit operation status, characterized in that: The following steps are involved: Step 1: The voltage acquisition board collects the positive half DC voltage U of the buffer absorption circuit in real time. AN And the negative half group DC voltage U BN , and process them separately according to the on / off status of IGCT. If IGCT is on, proceed to step 2, otherwise proceed to step 3; The buffer absorption circuit includes an inductor L1, an inductor L2, a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a diode D8, a switch tube V1, a switch tube V2, a switch tube V3 and a switch tube V4. One end of the inductor L1 is connected to the positive electrode of the AC power supply of the main circuit. The other end of the inductor L1 is connected to the positive electrode of the diode D7, the collector of the switch tube V1 and the negative electrode of the diode D1 respectively. The negative electrode of the diode D7 is connected in series with the capacitor C1, the capacitor C2 and the positive electrode of the diode D8. The negative electrode of the diode D8 is connected to one end of the inductor L2, the emitter of the switch tube V4 and the positive electrode of the diode D4 respectively. The other end of the inductor L2 is connected to the negative electrode of the AC power supply of the main circuit. The resistor R1 is connected in parallel to the inductor L1 and the diode D4. On the diode D7, the resistor R2 is connected in parallel to the inductor L2 and the diode D8, the switch tubes V1, V2, V3 and V4 are connected in series in the form of the emitter connecting the collector, the diodes D1, D2, D3 and D4 are connected in series in the form of the positive electrode connecting the negative electrode, the neutral line of the main circuit is respectively connected to the series node of the capacitor C1 and the capacitor C2, the positive electrode of the diode D5 and the negative electrode of the diode D6, the negative electrode of the diode D5 is respectively connected to the series node of the switch tube V1 and the switch tube V2 and the series node of the diode D1 and the diode D2, the positive electrode of the diode D6 is respectively connected to the series node of the switch tube V3 and the switch tube V4 and the series node of the diode D3 and the diode D4, the series node of the switch tube V2 and the switch tube V3 is connected to the series node of the diode D2 and the diode D3 and outputs the load current ; The voltage collection board is connected to the series node A of the inductor L1 and the diode D7, the series node N of the capacitor C1 and the capacitor C2, and the series node B of the inductor L2 and the diode D8, respectively, to collect the positive half group DC voltage U of the buffer absorption loop. AN And the negative half group DC voltage U BN , and the positive half group DC voltage U AN And the negative half group DC voltage U BN Input to the control board; Step 2: When the IGCT is turned on, detect the voltage U AN and U BN Data waveform U AN and U BN The duration is zero and according to U AN and U BN The duration of zero determines whether a short-circuit through fault occurs; Step 3: When IGCT is turned off, intercept U AN and U BN The data waveform triggers the shutdown signal within 40us. AN and U BN The waveform data is obtained, and the peak voltage and peak time are extracted as characteristic values, which are sent to the numerical fitting observer in the control board to calculate the estimated values ​​of the R value and C value of the current buffer absorption circuit; the estimated values ​​of the R value and C value are compared with the saved initial values ​​of the R value and C value of the buffer absorption circuit to determine the operating status of the buffer absorption circuit.

2. The IGCT short circuit fault and main circuit operation status monitoring method according to claim 1 is characterized in that: The method for determining whether a short-circuit through fault occurs in step 2 is: >0, and the switch state changes to V3 off and V1 on, detect U AN ≈0 time, if it exceeds the threshold, it is considered that a straight-through fault occurs; When the load current <0, and the switch state changes to V2 off and V4 on, detect U BN ≈0. If the time exceeds the threshold, it is considered that a straight-through failure occurs.

3. The IGCT short circuit fault and main circuit operation status monitoring method according to claim 1 is characterized in that: The step 3 comprises the following steps: Step 3.1, set the counter to 0; Step 3.2, generating a shutdown signal; Step 3.3: The voltage acquisition board continuously collects U AN and U BN Data waveform; Step 3.4: Determine whether the duration exceeds 40us. If so, proceed to step 3.5; otherwise, return to step 3.

3. Step 3.5: Find U AN or U BN Data maximum value and its corresponding time position ; Step 3.6: Add the and The actual value of is input into the numerical fitting observer in the control board card, and the estimated values ​​of R value and C value of the buffer absorption circuit are calculated. The estimated values ​​of R value and C value of the buffer absorption circuit are compared with the initial values ​​of R value and C value set for the buffer absorption circuit. If they are within the range of the initial values, step 3.7 is performed, otherwise step 3.8 is performed; Step 3.7, the counter is reset to zero, judging that the buffer absorption circuit is operating normally and the monitoring is ended; Step 3.8, determine that the buffer absorption circuit is operating abnormally, and the counter value is +1; determine whether the counter value is greater than or equal to 3. If the counter value is greater than or equal to 3, proceed to step 3.9, otherwise return to step 3.2; Step 3.9: If the initial value range of R and C set in the buffer absorption circuit is exceeded three times in a row, a normal shutdown or alarm is requested, and this monitoring ends.

4. An IGCT short-circuit fault and main circuit operation status monitoring circuit, used to implement the IGCT short-circuit fault and main circuit operation status monitoring according to any one of claims 1 to 3, characterized in that: It includes a voltage acquisition board and a control board. The voltage acquisition board is connected to the buffer absorption circuit to collect the positive half group DC voltage U of the buffer absorption circuit. AN And the negative half group DC voltage U BN And input to the control board, the control board monitors the IGCT short circuit fault and the main circuit operation status.

5. The IGCT short-circuit fault and main circuit operation status monitoring circuit according to claim 4 is characterized in that: The control board includes a numerical fitting observer, which includes a numerical normalization module, a nonlinear fitting module, a linear fitting module and a numerical denormalization module connected in sequence. The input end of the numerical normalization module is connected to the voltage acquisition board, and the numerical denormalization module outputs the estimated values ​​of the R value and the C value of the buffer absorption loop.

6. The IGCT short-circuit fault and main circuit operation status monitoring circuit according to claim 5, characterized in that: The specific structure of the numerical normalization module is the u+c1 module, k1 module and u-1 module connected in sequence, the specific structure of the nonlinear fitting module is the added w1 module and b1 module input into the hyperbolic function module, the specific structure of the linear fitting module is the w2 module and b2 module input into the straight line function module, and the specific structure of the numerical denormalization module is the u+c2 module, k2 module and u+1 module connected in sequence, wherein c1 and k1 are numerical normalization coefficient matrices, w1 and b1 are nonlinear fitting coefficient matrices, w2 and b2 are linear fitting coefficient matrices, c2 and k2 are numerical denormalization coefficient matrices, and c1, k1, w1, b1, w2, b2, c2 and k2 are obtained by inputting input data and target data into the neural network for training.

7. The IGCT short-circuit fault and main circuit operation status monitoring circuit according to claim 6, characterized in that: The relationship between the input data and the output data is: in, is the intermediate calculation variable, To buffer the absorption loop inductance, To buffer the absorption circuit capacitor, To buffer the absorption loop resistance, is the intermediate calculation variable, is the intermediate calculation variable, is the load current, is the peak voltage, is the peak time.

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