Short-circuit detection and protection circuit for IGBT and short-circuit detection and protection method thereof

Abstract

The application provides an IGBT short circuit detection and protection circuit and a short circuit detection and protection method thereof. The IGBT short circuit detection circuit comprises a sampling circuit, a comparison circuit and a timing circuit. The timing circuit is connected to the comparison circuit, and the comparison circuit is connected to the sampling circuit. The sampling circuit is used for connecting the stray inductance between the auxiliary emitter and the power emitter of the IGBT to be tested. The sampling circuit is used for collecting the voltage of the stray inductance. The comparison circuit is used for comparing the voltage of the stray inductance with a preset reference voltage and outputting a first signal according to the comparison result. The timing circuit is used for outputting a second signal indicating whether the IGBT to be tested has a short circuit according to the length of time that the first signal is in a preset level state. The length of time that the first signal is in the preset level state is the duration of the rising edge of the current flowing through the stray inductance. The application improves the response speed of the short circuit detection of the IGBT, thereby reducing the damage risk of the IGBT in the short circuit and improving the safety of the IGBT.

Description

[Technical Field]

[0001] This application relates to the field of power electronic device technology, and in particular to an IGBT short-circuit detection and protection circuit and its short-circuit detection and protection method. [Background Technology]

[0002] An IGBT (Insulated Gate Bipolar Transistor) is a composite, fully controllable, voltage-driven power semiconductor device composed of a BJT (Bipolar Junction Transistor) and a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). It combines the advantages of both devices, namely, low drive power and low saturation voltage drop, making it very suitable for use in converter systems with DC voltages of 600V and above, such as AC motors, frequency converters, switching power supplies, and lighting circuits.

[0003] In related technologies, short-circuit detection of IGBTs typically employs desaturation detection, which detects whether a short circuit has occurred by detecting the occurrence of a specific phenomenon. This specific phenomenon is defined as "under a certain short-circuit current condition, the IGBT not only exits the saturation region, but its terminal voltage also becomes the voltage it had when turned off." Specifically, desaturation detection can generally be implemented in two ways: one is with a high-voltage diode and a comparator, and the other is with a resistor chain and a comparator. However, regardless of the implementation method used, desaturation detection still carries significant risks, which will be briefly analyzed below.

[0004] When the short-circuit current reaches four times or more of the IGBT's rated current, the IGBT will exit the saturation region, meaning its terminal voltage will rise to the voltage amplitude at which it was turned off. After exiting the saturation region, the IGBT will be in a state of "rapidly increasing transient power consumption," which typically lasts for about 10μs (i.e., four times the IGBT's rated current). The larger the short-circuit current, the shorter the duration of this state. Therefore, the circuit protecting the IGBT needs to safely and reliably turn it off within the duration of this state to prevent damage. However, to prevent false triggering and avoid affecting the normal operation of the IGBT, the desaturation detection method usually employs filtering. Under low-voltage, low-power conditions, the filtering time is relatively short, typically 3-6μs; under high-voltage, high-power conditions, the filtering time is longer, generally exceeding 7μs. It is understandable that the longer the filtering time, the greater the risk of IGBT damage. Because the filtering process takes time, or rather, consumes a significant amount of time, the response speed for short-circuit detection / protection of the IGBT is slower. This means the protection circuit cannot safely and reliably turn off the IGBT within the required timeframe, leading to IGBT damage. Furthermore, even if the IGBT is not damaged, the bonding wires attached to the IGBT chip can be damaged at the bonding surface due to contact impedance, thus affecting the IGBT's performance. All of the above increases the risk of IGBT damage during short circuits and reduces its safety.

[0005] Therefore, it is necessary to improve the existing IGBT short-circuit detection / protection circuit. [Summary of the Invention]

[0006] This application provides an IGBT short-circuit detection and protection circuit and its short-circuit detection and protection method, aiming to solve the problem of slow response speed when performing short-circuit detection / protection on IGBTs in related technologies.

[0007] To address the aforementioned technical problems, the first aspect of this application provides an IGBT short-circuit detection circuit, including a sampling circuit, a comparison circuit, and a timing circuit; wherein the timing circuit is connected to the comparison circuit, the comparison circuit is connected to the sampling circuit, and the sampling circuit is used to connect the stray inductance between the auxiliary emitter and the power emitter in the IGBT under test.

[0008] The sampling circuit is used to acquire the voltage of the stray inductor;

[0009] The comparison circuit is used to compare the voltage of the stray inductor with a preset reference voltage, and output a first signal according to the comparison result;

[0010] The timing circuit is used to output a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level. The duration of the first signal being at the preset level is the duration of the rising edge of the current flowing through the stray inductor.

[0011] A second aspect of this application provides an IGBT short-circuit detection method, applied to the IGBT short-circuit detection circuit described in the first aspect of this application; the IGBT short-circuit detection method includes:

[0012] The sampling circuit acquires the voltage of the stray inductor;

[0013] The comparison circuit compares the voltage of the stray inductor with a preset reference voltage and outputs a first signal based on the comparison result.

[0014] The timing circuit outputs a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level. The duration of the first signal being at the preset level is the duration of the rising edge of the current flowing through the stray inductor.

[0015] A third aspect of this application provides an IGBT short-circuit protection circuit, including a control circuit and an IGBT short-circuit detection circuit as described in the first aspect of this application; wherein, the timing circuit is connected to the control circuit, and the control circuit is used to connect the IGBT under test;

[0016] The control circuit is used to turn on the IGBT under test or turn off the IGBT under test according to the second signal.

[0017] A fourth aspect of this application provides an IGBT short-circuit protection method, applied to the IGBT short-circuit protection circuit described in the third aspect of this application; the IGBT short-circuit protection method includes:

[0018] The sampling circuit acquires the voltage of the stray inductor;

[0019] The comparison circuit compares the voltage of the stray inductor with a preset reference voltage and outputs a first signal based on the comparison result.

[0020] The timing circuit outputs a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level. The duration of the first signal being at the preset level is the duration of the rising edge of the current flowing through the stray inductor.

[0021] The control circuit turns on the IGBT under test or turns off the IGBT under test according to the second signal.

[0022] As can be seen from the above description, compared with related technologies, the beneficial effects of this application are as follows:

[0023] First, the voltage of the stray inductor is acquired through a sampling circuit; then, the voltage of the stray inductor is compared with a preset reference voltage through a comparison circuit, and a first signal is output based on the comparison result; finally, a timing circuit outputs a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level. The duration of the first signal being at the preset level is the duration of the rising edge of the current flowing through the stray inductor. Therefore, this application directly detects the duration of the rising edge of the current flowing through the stray inductor when performing short-circuit detection on the IGBT under test. The filtering time for the rising edge of the current flowing through the stray inductor, whether for low-voltage, low-power or high-voltage, high-power applications, will not exceed 3μs, thereby improving the response speed for short-circuit detection of the IGBT, reducing the risk of damage to the IGBT during a short circuit, and also improving the safety of the IGBT. [Attached Image Description]

[0024] To more clearly illustrate the related technologies or the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the related technologies or the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application, and not all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a first module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application;

[0026] Figure 2 This is a second module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application;

[0027] Figure 3 A schematic diagram of the circuit structure of the IGBT short-circuit detection circuit provided in the embodiments of this application;

[0028] Figure 4 This is a third module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application;

[0029] Figure 5 This is a fourth module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application;

[0030] Figure 6A schematic flowchart illustrating the IGBT short-circuit detection method provided in this application embodiment;

[0031] Figure 7 A module block diagram of the IGBT short-circuit protection circuit provided in the embodiments of this application;

[0032] Figure 8 This is a flowchart illustrating the IGBT short-circuit protection method provided in an embodiment of this application.

Detailed Implementation Methods

[0033] To make the objectives, technical solutions, and advantages of this application more apparent and understandable, the application will be clearly and completely described below in conjunction with the embodiments and corresponding drawings. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. It should be understood that the various embodiments of this application described below are merely illustrative and not intended to limit the application. That is, all other embodiments obtained by those skilled in the art based on the various embodiments of this application without creative effort are within the scope of protection of this application. Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0034] In related technologies, short-circuit detection of IGBTs typically employs desaturation detection, which detects whether a short circuit has occurred by detecting the occurrence of a specific phenomenon. This specific phenomenon is defined as "under a certain short-circuit current condition, the IGBT not only exits the saturation region, but its terminal voltage also becomes the voltage it had when turned off." Specifically, desaturation detection can generally be implemented in two ways: one is with a high-voltage diode and a comparator, and the other is with a resistor chain and a comparator. However, regardless of the implementation method used, desaturation detection still carries significant risks, which will be briefly analyzed below.

[0035] When the short-circuit current reaches four times or more of the IGBT's rated current, the IGBT will exit the saturation region, meaning its terminal voltage will rise to the voltage amplitude at which it was turned off. After exiting the saturation region, the IGBT will be in a state of "rapidly increasing transient power consumption," which typically lasts for about 10μs (i.e., four times the IGBT's rated current). The larger the short-circuit current, the shorter the duration of this state. Therefore, the circuit protecting the IGBT needs to safely and reliably turn it off within the duration of this state to prevent damage. However, to prevent false triggering and avoid affecting the normal operation of the IGBT, the desaturation detection method usually employs filtering. Under low-voltage, low-power conditions, the filtering time is relatively short, typically 3-6μs; under high-voltage, high-power conditions, the filtering time is longer, generally exceeding 7μs. It is understandable that the longer the filtering time, the greater the risk of IGBT damage. Because the filtering process takes time, or rather, the longer the filtering time, the slower the response speed during IGBT short-circuit detection. This means the circuit protecting the IGBT cannot safely and reliably turn it off within the required timeframe, leading to IGBT damage. Furthermore, even if the IGBT is not damaged, the bonding wires attached to the IGBT chip will suffer damage at the bonding surface due to contact impedance, affecting IGBT performance. All of the above increases the risk of IGBT damage during short circuits and reduces its safety. Therefore, this application provides an IGBT short-circuit detection circuit.

[0036] Before describing in detail the IGBT short-circuit detection circuit provided in the embodiments of this application, the detection principle on which the IGBT short-circuit detection circuit provided in the embodiments of this application is based will be briefly explained as follows:

[0037] When the IGBT is normally turned on, the current flowing through the stray inductance between the auxiliary emitter and the power emitter in the IGBT and the voltage amplitude generated therein have the following relationship:

[0038]

[0039] In this context, the auxiliary emitter of the IGBT is used as the reference ground; V is the voltage amplitude, L is the inductance of the stray inductor, t is time, I is the current flowing through the stray inductor, dI is the derivative of I, and dt is the derivative of t. Based on this, when the IGBT is short-circuited, I rises sharply, and the duration of the rising edge of I is significantly longer than the duration of the rising edge when the IGBT is normally turned on. This embodiment utilizes this difference to achieve short-circuit detection of the IGBT. Specifically, this embodiment detects the duration of the rising edge of I, and when the phenomenon that "the duration of the rising edge of I is longer than the duration of the rising edge when the IGBT is normally turned on" is detected, it can be determined that the IGBT has short-circuited. The following section will elaborate on the IGBT short-circuit detection circuit provided in this application embodiment, based on the detection principle shown in this paragraph. In the following text, the same symbol can represent both the corresponding electrical parameter and its value. For example, when V1 is present in the formula, it represents the voltage value of the first voltage; when V1 is not present in the formula, it represents the first voltage. Similarly, when R1 is present in the formula, it represents the resistance value of the first resistor; when R1 is not present in the formula, it represents the first resistor. Furthermore, when VCC is present in the formula, it represents the voltage value of the first power supply; when VCC is not present in the formula, it represents the first power supply. Finally, when Vref1 is present in the formula, it represents the voltage value of the first reference voltage; when Vref1 is not present in the formula, it represents the first reference voltage.

[0040] Please see Figure 1 , Figure 1 This is a first module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application; from Figure 1 As can be seen from the embodiments, the IGBT short-circuit detection circuit provided in this application includes a sampling circuit 100, a comparison circuit 200, and a timing circuit 300. The timing circuit 300 is connected to the comparison circuit 200, which is connected to the sampling circuit 100. The sampling circuit 100 is used to connect the stray inductance between the auxiliary emitter and the power emitter of the IGBT under test. It is necessary to explain here that in the IGBT under test, the stray inductance is connected between the auxiliary emitter and the power emitter; in this case, the auxiliary emitter of the IGBT under test can be used as a reference ground.

[0041] Specifically, the sampling circuit 100 is used to acquire the voltage of the stray inductor; the comparison circuit 200 is used to compare the voltage of the stray inductor with a preset reference voltage and output a first signal according to the comparison result; the timing circuit 300 is used to output a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level; wherein, the duration of the first signal being at the preset level is equivalent to the duration of the rising edge of the current flowing through the stray inductor.

[0042] In practical applications, when short-circuit detection of the IGBT under test is required, the voltage of the stray inductor can be collected first by the sampling circuit 100 and the collected stray inductor voltage can be output to the comparison circuit 200. Then, the comparison circuit 200 compares the stray inductor voltage with a preset reference voltage and outputs a first signal to the timing circuit 300 based on the comparison result. Finally, the timing circuit 300 outputs a second signal indicating whether the IGBT under test has short-circuited based on the duration of the first signal being at a preset level. Thus, the short-circuit status of the IGBT under test can be confirmed based on the second signal.

[0043] As can be seen from the above, when performing short-circuit detection on the IGBT under test, this embodiment directly detects the duration of the rising edge of the current flowing through the stray inductor. The filtering time for the rising edge of the current flowing through the stray inductor, whether for low-voltage, low-power or high-voltage, high-power applications, will not exceed 3μs. This improves the response speed of IGBT short-circuit detection, thereby reducing the risk of damage to the IGBT during a short circuit and enhancing its safety. Furthermore, since this embodiment does not require detection of specific phenomena (i.e., under certain short-circuit current conditions, the IGBT not only exits the saturation region but its terminal voltage also becomes the voltage at turn-off), but directly detects the current flowing through the stray inductor, this embodiment also has the excellent characteristic of being less prone to false alarms.

[0044] As one possible implementation method, please refer to further information. Figure 2 , Figure 2 This is a second module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application; from Figure 2 As can be seen, the sampling circuit 100 may include a voltage divider branch 110. Specifically, the voltage divider branch 110 can be used to acquire a first voltage of the stray inductor, divide the acquired first voltage to obtain a second voltage, and output the obtained second voltage to the comparator circuit 200. Here, it is necessary to explain that in this embodiment, both the first voltage and the second voltage can be regarded as the voltage of the stray inductor; wherein, the first voltage is the actual voltage of the stray inductor, and the second voltage is obtained after performing a preset processing (i.e., voltage division) on this actual voltage.

[0045] It is understood that this embodiment does not directly output the collected stray inductor voltage to the comparator circuit 200 after collecting the stray inductor voltage. Instead, it first collects the stray inductor voltage, then divides the collected stray inductor voltage, and finally outputs the divided stray inductor voltage to the comparator circuit 200. That is, it first collects the first voltage of the stray inductor, then divides the collected first voltage to obtain the second voltage, and finally outputs the obtained second voltage to the comparator circuit 200 so that the comparator circuit 200 can compare the second voltage with a preset reference voltage.

[0046] As one specific implementation of this method, please refer to further details. Figure 3 , Figure 3 This is a schematic diagram of the circuit structure of the IGBT short-circuit detection circuit provided in the embodiments of this application; from Figure 3 As can be seen from the diagram, the voltage divider branch 110 may include a first diode D1, a second diode D2, a first resistor R1, and a second resistor R2; wherein, the cathode of the first diode D1 and one end of the first resistor R1 are used to connect to the first power supply VCC, one end of the second resistor R2, the other end of the first resistor R1, and the anode of the first diode D1 are respectively connected to the cathode of the second diode D2, the anode of the second diode D2 is grounded, and the other end of the second resistor R2 is used to connect to one end of the stray inductance Ls.

[0047] In this specific implementation, the voltage divider branch 110 can be used to acquire the first voltage V1 of the stray inductor Ls, and to divide the acquired first voltage V1 by the first resistor R1 and the second resistor R2 to obtain the second voltage V2. The obtained second voltage V2 is then output to the comparator circuit 200 through the common contact between the first diode D1 and the second diode D2. It can be understood that after the voltage divider branch 110 outputs the obtained second voltage V2 to the comparator circuit 200, the comparator circuit 200 can compare the second voltage V2 with a preset reference voltage. Furthermore, when the IGBT under test is normally turned on, the first voltage V1 of the stray inductor Ls remains essentially unchanged, meaning the second voltage V2 also remains essentially unchanged. When the IGBT under test experiences a short circuit, the current flowing through the stray inductor Ls increases sharply, causing the first voltage V1 of the stray inductor Ls to gradually decrease, which in turn causes the second voltage V2 to gradually decrease as well.

[0048] In this specific implementation, the negative voltage region of the second voltage V2 is utilized, while the positive voltage region of the second voltage V2 is ignored. According to the principle of resistor voltage division, the second voltage V2 can be expressed by the following formula:

[0049]

[0050] In practical applications, a double-pulse test can be performed, and based on the results of the double-pulse test, the amplitude range of the first voltage V1 can be obtained. In addition, the voltage value of the second voltage V2 cannot exceed the power supply range of the comparator circuit 200. At this time, the ratio of the first resistor R1 and the second resistor R2 can be adjusted according to actual needs.

[0051] It should be understood that the above-described embodiments are merely preferred implementations of the present application and are not the only limitation on the specific configuration of the sampling circuit 100 in the present application. Those skilled in the art can make flexible settings based on the present application embodiments and actual application scenarios.

[0052] As one possible implementation method, please refer to further information. Figure 4 , Figure 4 This is a third module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application; from Figure 4 As can be seen from the diagram, the comparison circuit 200 may include a first comparison branch 210 and a second comparison branch 220; wherein, the input terminals of the first comparison branch 210 and the second comparison branch 220 are respectively connected to the sampling circuit 100, and the output terminals of the first comparison branch 210 and the second comparison branch 220 are respectively connected to the timing circuit 300.

[0053] Specifically, the first comparison branch 210 can be used to receive the second voltage V2 output by the sampling circuit 100, compare the second voltage V2 with a preset first reference voltage Vref1, and output a first sub-signal OC1 to the timing circuit 300 according to the comparison result; the second comparison branch 220 can be used to receive the second voltage V2 output by the sampling circuit 100, compare the second voltage V2 with a preset second reference voltage Vref2, and output a second sub-signal OC2 to the timing circuit 300 according to the comparison result. Here, it is necessary to explain that both the first sub-signal OC1 and the second sub-signal OC2 are the first signal mentioned above.

[0054] It can be understood that after the first comparison branch 210 outputs the first sub-signal OC1 to the timing circuit 300, and the second comparison branch 220 outputs the second sub-signal OC2 to the timing circuit 300, the timing circuit 300 can output a second signal SC indicating whether the IGBT under test has a short circuit, based on the duration of the first sub-signal OC1 being in the preset level state and the duration of the second sub-signal OC2 being in the preset level state; wherein, the total duration of the first sub-signal OC1 and the second sub-signal OC2 being in the preset level state is the duration of the rising edge of the current flowing through the stray inductor Ls.

[0055] As one specific implementation of this method, please refer to [the original text]. Figure 3The first comparison branch 210 may include a first comparator COMP1 and a first pull-up resistor R5; the second comparison branch 220 may include a second comparator COMP2 and a second pull-up resistor R6. Specifically, the non-inverting input terminals of the first comparator COMP1 and the second comparator COMP2 are respectively connected to the common junction between the first diode D1 and the second diode D2. The inverting input terminal of the first comparator COMP1 is connected to the first reference voltage Vref1, and the inverting input terminal of the second comparator COMP2 is connected to the second reference voltage Vref2. The first output terminal of the first comparator COMP1 is connected to the first power supply VCC, and the second output terminal of the first comparator COMP1 is grounded. The third output terminal of the first comparator COMP1 and one end of the first pull-up resistor R5 are respectively connected to the timing circuit 300, and the other end of the first pull-up resistor R5 is connected to the second power supply VDD. The output terminal of the second comparator COMP2 and one end of the second pull-up resistor R6 are respectively connected to the timing circuit 300, and the other end of the second pull-up resistor R6 is connected to the second power supply VDD.

[0056] In this specific implementation, the first comparison branch 210 can be used to compare the second voltage V2 with the first reference voltage Vref1 through the first comparator COMP1, and output the first sub-signal OC1 to the timing circuit 300 through its third output terminal according to the comparison result; wherein, when the second voltage V2 is greater than the first reference voltage Vref1, the first sub-signal OC1 remains at a high level; when the second voltage V2 is less than the first reference voltage Vref1, the first sub-signal OC1 changes from a high level to a low level. The second comparison branch 220 can be used to compare the second voltage V2 with the second reference voltage Vref2 through the second comparator COMP2, and output the second sub-signal OC2 to the timing circuit 300 according to the comparison result; wherein, when the second voltage V2 is greater than the second reference voltage Vref2, the second sub-signal OC2 remains at a high level; when the second voltage V2 is less than the second reference voltage Vref2, the second sub-signal OC2 changes from a high level to a low level.

[0057] In this specific implementation, when the IGBT under test is normally turned on, the second voltage V2 remains basically unchanged. At this time, the second voltage V2 is greater than both the first reference voltage Vref1 and the second reference voltage Vref2. That is, the first sub-signal OC1 output by the first comparator COMP1 and the second sub-signal OC2 output by the second comparator COMP2 both remain at a high level. When the IGBT under test is short-circuited, the current flowing through the stray inductor Ls rises sharply, so the second voltage V2 will gradually decrease. When the second voltage V2 decreases to less than the first reference voltage Vref1, the first sub-signal OC1 output by the first comparator COMP1 will change from a high level to a low level. Similarly, when the second voltage V2 decreases to less than the second reference voltage Vref2, the second sub-signal OC2 output by the second comparator COMP2 will also change from a high level to a low level.

[0058] In practical applications, the first reference voltage Vref1 and the second reference voltage Vref2 can be set to have different magnitudes. For example, the first reference voltage Vref1 can be set to be less than the second reference voltage Vref2, and the two can satisfy the following relationship:

[0059]

[0060] At this point, the first reference voltage Vref1 corresponds to the case of a shoot-through short circuit in the IGBT under test, and the second reference voltage Vref2 corresponds to the case of a phase-to-phase short circuit in the IGBT under test. It can be understood that, given the difference in magnitude between the first reference voltage Vref1 and the second reference voltage Vref2, when the IGBT under test experiences a short circuit, as the second voltage V2 gradually decreases, the second sub-signal OC2 output by the second comparator COMP2 will first change from high to low, and the first sub-signal OC1 output by the first comparator COMP1 will subsequently change from high to low.

[0061] It should be understood that the above-described embodiments are merely preferred implementations of the present application and are not the only limitation on the specific configuration of the comparison circuit 200 in the present application. Those skilled in the art can make flexible settings based on the present application embodiments and actual application scenarios.

[0062] As one possible implementation method, please refer to further information. Figure 5 , Figure 5 This is a fourth module block diagram of the IGBT short-circuit detection circuit provided in the embodiments of this application; from Figure 5As can be seen from the diagram, the timing circuit 300 may include a first timing branch 310, a second timing branch 320, and an OR gate HM; wherein, the input terminal of the first timing branch 310 is connected to the output terminal of the first comparison branch 210, the input terminal of the second timing branch 320 is connected to the output terminal of the second comparison branch 220, and the output terminals of the first timing branch 310 and the second timing branch 320 are respectively connected to the OR gate HM.

[0063] Specifically, the first timing branch 310 can be used to receive the first sub-signal OC1 output by the first comparison branch 210, and when the first sub-signal OC1 is at a preset level, output an increased third voltage V3 to an OR gate HM, and when the first sub-signal OC1 is at other level states, output a decreased third voltage V3 to an OR gate HM. In this embodiment, a low level state is used as the preset level state, so when the first sub-signal OC1 is at a low level state, the first timing branch 310 outputs an increased third voltage V3 to an OR gate HM; when the first sub-signal OC1 is at a high level state, the first timing branch 310 outputs a decreased third voltage V3 to an OR gate HM.

[0064] The second timing branch 320 can be used to receive the second sub-signal OC2 output by the second comparison branch 220, and when the second sub-signal OC2 is at a preset level, it outputs an increased fourth voltage V4 to the OR gate HM, and when the second sub-signal OC2 is at other levels, it outputs a decreased fourth voltage V4 to the OR gate HM. Since the preset level is a low level, when the second sub-signal OC2 is at a low level, the second timing branch 320 will output an increased fourth voltage V4 to the OR gate HM; when the second sub-signal OC2 is at a high level, the second timing branch 320 will output a decreased fourth voltage V4 to the OR gate HM.

[0065] The OR gate HM can be used to output a second signal SC indicating that the IGBT under test has short-circuited when the sum of the third voltage V3 and the fourth voltage V4 is greater than or equal to the switching threshold voltage of the OR gate HM, and to output a second signal SC indicating that the IGBT under test has not short-circuited when the sum of the third voltage V3 and the fourth voltage V4 is less than the switching threshold voltage of the OR gate HM; wherein, when the total duration of the first sub-signal OC1 and the second sub-signal OC2 being in a low-level state is greater than or equal to a preset duration, the sum of the third voltage V3 and the fourth voltage V4 is greater than or equal to the switching threshold voltage of the OR gate HM; when the total duration of the first sub-signal OC1 and the second sub-signal OC2 being in a low-level state is less than the preset duration, the sum of the third voltage V3 and the fourth voltage V4 is less than the switching threshold voltage of the OR gate HM.

[0066] It can be understood that if the total duration of the first sub-signal OC1 and the second sub-signal OC2 being in a low-level state is greater than or equal to the preset duration, it is equivalent to the total duration of the third voltage V3 and the fourth voltage V4 being in an increasing trend being greater than or equal to the preset duration. This means that only when the total duration of the third voltage V3 and the fourth voltage V4 being in an increasing trend is sufficient will the sum of the third voltage V3 and the fourth voltage V4 be greater than or equal to the switching threshold voltage of the OR gate HM. At this time, the OR gate HM will output the second signal SC indicating that the IGBT under test has a short circuit. Correspondingly, if the total duration of the first sub-signal OC1 and the second sub-signal OC2 being in a low-level state is less than the preset duration, it is equivalent to the total duration of the third voltage V3 and the fourth voltage V4 being in an increasing trend being less than the preset duration. This means that the total duration of the third voltage V3 and the fourth voltage V4 being in an increasing trend is too short, and the sum of the third voltage V3 and the fourth voltage V4 has not yet exceeded or equaled the switching threshold voltage of the OR gate HM. At this time, the OR gate HM will output the second signal SC indicating that the IGBT under test has not a short circuit.

[0067] As one specific implementation of this method, please refer to [the original text]. Figure 3 The first timing branch 310 may include a first NOT gate F1, a third diode D3, a third resistor R3, and a first capacitor C1; wherein, the first input terminal of the OR gate HM, one end of the first capacitor C1, and the anode of the third diode D3 are respectively connected to one end of the third resistor R3, the other end of the first capacitor C1 is grounded, the other end of the third resistor R3 and the cathode of the third diode D3 are respectively connected to the output terminal of the first NOT gate F1, and the input terminal of the first NOT gate F1 is connected to the third output terminal of the first comparator COMP1. The second timing branch 320 may include a second NOT gate F2, a fourth diode D4, a fourth resistor R4, and a second capacitor C2; wherein, the second input terminal of the OR gate HM, one end of the second capacitor C2, and the anode of the fourth diode D4 are respectively connected to one end of the fourth resistor R4, the other end of the second capacitor C2 is grounded, the other end of the fourth resistor R4 and the cathode of the fourth diode D4 are respectively connected to the output terminal of the second NOT gate F2, and the input terminal of the second NOT gate F2 is connected to the output terminal of the second comparator COMP2.

[0068] In this specific implementation, the first timing branch 310 can be used to receive the first sub-signal OC1 output by the first comparator COMP1, and when the first sub-signal OC1 changes from high level to low level (i.e., the output of the first NOT gate F1 changes from low level to high level), it charges the first capacitor C1 through the third resistor R3 to increase the terminal voltage of the first capacitor C1, and when the first sub-signal OC1 changes from low level to high level (i.e., the output of the first NOT gate F1 changes from high level to low level), it discharges the first capacitor C1 through the third diode D3 to decrease the terminal voltage of the first capacitor C1; wherein, the terminal voltage of the first capacitor C1 is the third voltage V3.

[0069] Specifically, the second timing branch 320 can be used to receive the second sub-signal OC2 output by the second comparator COMP2, and when the second sub-signal OC2 changes from high level to low level (i.e., the output of the second NOT gate F2 changes from low level to high level), it charges the second capacitor C2 through the fourth resistor R4 to increase the terminal voltage of the second capacitor C2, and when the second sub-signal OC2 changes from low level to high level (i.e., the output of the second NOT gate F2 changes from high level to low level), it discharges the second capacitor C2 through the fourth diode D4 to decrease the terminal voltage of the second capacitor C2; wherein, the terminal voltage of the second capacitor C2 is the fourth voltage V4.

[0070] Specifically, the OR gate HM can be used to output a second signal SC that indicates the IGBT under test is not short-circuited when the total duration of the first sub-signal OC1 and the second sub-signal OC2 being at a low level is less than a preset duration (i.e., the sum of the third voltage V3 and the fourth voltage V4 is less than the switching threshold voltage of the OR gate HM), and to output a second signal SC that indicates the IGBT under test is short-circuited when the total duration of the first sub-signal OC1 and the second sub-signal OC2 being at a low level is greater than or equal to a preset duration (i.e., the sum of the third voltage V3 and the fourth voltage V4 is greater than or equal to the switching threshold voltage of the OR gate HM).

[0071] In this specific implementation, when the IGBT under test is normally turned on, the second signal SC remains low to indicate that the IGBT under test is not short-circuited; when the IGBT under test is short-circuited, the second signal SC changes from low to high to indicate that the IGBT under test is short-circuited. In practical applications, the duration for which the first sub-signal OC1 and the second sub-signal OC2 are low (i.e., the preset level state mentioned above) can be set by adjusting the values ​​of the third resistor R3 and the first capacitor C1, and the fourth resistor R4 and the second capacitor C2, respectively. It is necessary to clarify that only when the total duration of the first sub-signal OC1 and the second sub-signal OC2 being low is greater than or equal to the preset duration will the sum of the third voltage V3 and the fourth voltage V4 be greater than or equal to the switching threshold voltage of the OR gate HM, and only then will the second signal SC output by the OR gate HM change, i.e., change from low to high to indicate that the IGBT under test is short-circuited.

[0072] As another specific implementation of this embodiment, in order to simplify the circuit, the timing circuit 300 can be replaced with a programmable digital control chip. The software logic burned into the digital control chip is the judgment logic performed by the timing circuit 300 for the first sub-signal OC1 and the second sub-signal OC2 in the above specific implementation, which will not be described in detail here.

[0073] It should be understood that the above-described embodiments are merely preferred implementations of the present application and are not the only limitation on the specific configuration of the timing circuit 300 in the present application. Those skilled in the art can make flexible settings based on the present application embodiments and actual application scenarios.

[0074] In summary, the IGBT short-circuit detection circuit provided in this application includes a sampling circuit 100, a comparator circuit 200, and a timing circuit 300. Each of these circuits has a preferred configuration. From these configurations, it can be seen that this application not only improves the response speed and reduces the false alarm probability when detecting short circuits in IGBTs, but also eliminates the need for numerous resistor chains or high-voltage diodes used for high-voltage isolation compared to the two traditional desaturation detection methods (i.e., high-voltage diodes with comparators and resistor chains with comparators), resulting in a simpler circuit structure, lower cost, and smaller PCB footprint. Furthermore, it is worth mentioning that the IGBT short-circuit detection circuit provided in this application is not only applicable to IGBT short-circuit detection but also to short-circuit detection of other transistors commonly found in the art, such as SiC-doped transistors, differing only in the length of the filtering time.

[0075] Please see Figure 6 , Figure 6 This is a flowchart illustrating the IGBT short-circuit detection method provided in an embodiment of this application.

[0076] like Figure 6 As shown, this application embodiment also provides an IGBT short-circuit detection method, which is applied to the IGBT short-circuit detection circuit provided in this application embodiment, and the IGBT short-circuit detection method includes the following steps 601 to 603.

[0077] Step 601: The sampling circuit collects the voltage of the stray inductor.

[0078] In this embodiment of the application, when performing short-circuit detection on the IGBT under test, the voltage of the stray inductance Ls between the auxiliary emitter and the power emitter in the IGBT under test needs to be collected by the sampling circuit 100 first, and the collected voltage of the stray inductance Ls is output to the comparison circuit 200 so that the comparison circuit 200 can compare the voltage of the stray inductance Ls with a preset reference voltage.

[0079] Step 602: The comparison circuit compares the voltage of the stray inductor with the preset reference voltage and outputs the first signal based on the comparison result.

[0080] In this embodiment of the application, after the comparison circuit 200 receives the voltage of the stray inductance Ls sent by the sampling circuit 100, it also needs to compare the received voltage of the stray inductance Ls with a preset reference voltage, and output a first signal (i.e., the first sub-signal OC1 and the second sub-signal OC2) to the timing circuit 300 according to the comparison result, so that the timing circuit 300 can determine whether the IGBT under test has a short circuit according to the first signal.

[0081] Step 603: The timing circuit outputs a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level.

[0082] In this embodiment, after receiving the first signal from the comparator circuit 200, the timing circuit 300 also needs to output a second signal SC indicating whether the IGBT under test has short-circuited, based on the duration of the received first signal being at a preset level. This allows the timing circuit to confirm whether the IGBT under test has short-circuited based on the output second signal SC. It can be understood that since the duration of the first signal being at a preset level is equivalent to the duration of the rising edge of the current flowing through the stray inductor Ls, this embodiment actually determines whether the IGBT under test has short-circuited based on the duration of the rising edge of the current flowing through the stray inductor Ls.

[0083] Please see Figure 7 , Figure 7 This is a block diagram of the IGBT short-circuit protection circuit provided in an embodiment of this application.

[0084] like Figure 7 As shown, this application embodiment also provides an IGBT short-circuit protection circuit, including a control circuit 400 and an IGBT short-circuit detection circuit provided in this application embodiment; wherein, the timing circuit 300 is connected to the control circuit 400, and the control circuit 400 is used to connect the IGBT under test.

[0085] Specifically, the control circuit 400 receives the second signal SC output by the timing circuit 300 and turns on or off the IGBT under test according to the second signal SC. It can be understood that when the second signal SC output by the timing circuit 300 indicates that the IGBT under test is not short-circuited, the control circuit 400 will continue to turn on the IGBT under test to ensure its normal operation; when the second signal SC output by the timing circuit 300 indicates that the IGBT under test is short-circuited, the control circuit 400 will turn off the IGBT under test to protect it and prevent damage.

[0086] Please see Figure 8 , Figure 8 This is a flowchart illustrating the IGBT short-circuit protection method provided in an embodiment of this application.

[0087] like Figure 8 As shown, this application embodiment also provides an IGBT short-circuit protection method, applied to the IGBT short-circuit protection circuit provided in this application embodiment, and the IGBT short-circuit protection method includes the following steps 801 to 804.

[0088] Step 801: The sampling circuit collects the voltage of the stray inductor.

[0089] In this embodiment of the application, when performing short-circuit detection on the IGBT under test, the voltage of the stray inductance Ls between the auxiliary emitter and the power emitter in the IGBT under test needs to be collected by the sampling circuit 100 first, and the collected voltage of the stray inductance Ls is output to the comparison circuit 200 so that the comparison circuit 200 can compare the voltage of the stray inductance Ls with a preset reference voltage.

[0090] Step 802: The comparison circuit compares the voltage of the stray inductor with the preset reference voltage and outputs the first signal based on the comparison result.

[0091] In this embodiment of the application, after the comparison circuit 200 receives the voltage of the stray inductance Ls sent by the sampling circuit 100, it also needs to compare the received voltage of the stray inductance Ls with a preset reference voltage, and output a first signal (i.e., the first sub-signal OC1 and the second sub-signal OC2) to the timing circuit 300 according to the comparison result, so that the timing circuit 300 can determine whether the IGBT under test has a short circuit according to the first signal.

[0092] Step 803: The timing circuit outputs a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level.

[0093] In this embodiment, after receiving the first signal from the comparator circuit 200, the timing circuit 300 also needs to output a second signal SC indicating whether the IGBT under test has short-circuited, based on the duration of the received first signal being at a preset level. This allows the timing circuit to confirm whether the IGBT under test has short-circuited based on the output second signal SC. It can be understood that since the duration of the first signal being at a preset level is equivalent to the duration of the rising edge of the current flowing through the stray inductor Ls, this embodiment actually determines whether the IGBT under test has short-circuited based on the duration of the rising edge of the current flowing through the stray inductor Ls.

[0094] 804. The control circuit turns on or turns off the IGBT under test according to the second signal.

[0095] In this embodiment, after receiving the second signal SC from the timing circuit 300, the control circuit 400 needs to turn on or turn off the IGBT under test according to the received second signal SC. Specifically, when the second signal SC output by the timing circuit 300 indicates that the IGBT under test is not short-circuited, the control circuit 400 continues to turn on the IGBT under test to ensure its normal operation; when the second signal SC output by the timing circuit 300 indicates that the IGBT under test is short-circuited, the control circuit 400 turns off the IGBT under test to protect it and prevent damage.

[0096] It should be noted that the various embodiments in this application are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For method embodiments, since they are similar to product embodiments, the description is relatively simple; relevant parts can be referred to the descriptions of the product embodiments.

[0097] It should also be noted that, in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0098] The above description of the disclosed embodiments enables those skilled in the art to implement or use the content of this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in this application may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An IGBT short-circuit detection circuit, characterized in that, It includes a sampling circuit, a comparison circuit, and a timing circuit; wherein, the timing circuit is connected to the comparison circuit, the comparison circuit is connected to the sampling circuit, and the sampling circuit is used to connect the stray inductance between the auxiliary emitter and the power emitter in the IGBT under test; the sampling circuit includes a voltage divider branch; the comparison circuit includes a first comparison branch and a second comparison branch; the timing circuit includes a first timing branch, a second timing branch, and an OR gate; The sampling circuit is used to acquire the voltage of the stray inductor; The comparison circuit is used to compare the voltage of the stray inductor with a preset reference voltage, and output a first signal according to the comparison result; The timing circuit is used to output a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being in a preset level state; wherein, the duration of the first signal being in the preset level state is the duration of the rising edge of the current flowing through the stray inductor. The voltage divider branch is used to acquire the first voltage of the stray inductor, divide the first voltage to obtain the second voltage, and output the second voltage to the comparator circuit. The first comparison branch is used to compare the second voltage with a preset first reference voltage, and output a first sub-signal to the timing circuit according to the comparison result; The second comparison branch is used to compare the second voltage with a preset second reference voltage, and output a second sub-signal to the timing circuit according to the comparison result; The first reference voltage and the second reference voltage have the following relationship: Wherein, Vref1 is the voltage value of the first reference voltage, and Vref2 is the voltage value of the second reference voltage; The first timing branch is used to output an increased third voltage to the OR gate when the first sub-signal is at the preset level state, and to output a decreased third voltage to the OR gate when the first sub-signal is at other level states. The second timing branch is used to output an increased fourth voltage to the OR gate when the second sub-signal is at the preset level state, and to output a decreased fourth voltage to the OR gate when the second sub-signal is at other level states; The OR gate is used to output a second signal indicating that the IGBT under test has short-circuited when the sum of the third voltage and the fourth voltage is greater than or equal to the switching threshold voltage of the OR gate, and to output a second signal indicating that the IGBT under test has not short-circuited when the sum of the third voltage and the fourth voltage is less than the switching threshold voltage of the OR gate. Wherein, when the total duration of the first sub-signal and the second sub-signal being in the preset level state is greater than or equal to the preset duration, the sum of the third voltage and the fourth voltage is greater than or equal to the switching threshold voltage of the OR gate; when the total duration of the first sub-signal and the second sub-signal being in the preset level state is less than the preset duration, the sum of the third voltage and the fourth voltage is less than the switching threshold voltage of the OR gate; the total duration of the first sub-signal and the second sub-signal being in the preset level state is the duration of the rising edge of the current flowing through the stray inductor.

2. The IGBT short-circuit detection circuit as described in claim 1, characterized in that, The voltage divider branch includes a first diode, a second diode, a first resistor, and a second resistor; wherein, the cathode of the first diode and one end of the first resistor are used to connect to a first power supply, one end of the second resistor, the other end of the first resistor, and the anode of the first diode are respectively connected to the cathode of the second diode, the anode of the second diode is grounded, and the other end of the second resistor is used to connect to one end of the stray inductor. The voltage divider branch is specifically used to acquire the first voltage, and to divide the first voltage using the first resistor and the second resistor to obtain the second voltage, and to output the second voltage to the comparator circuit through the common contact between the first diode and the second diode; wherein, the second voltage is represented by the following formula: Wherein, V2 is the voltage value of the second voltage, V1 is the voltage value of the first voltage, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and VCC is the voltage value of the first power supply.

3. The IGBT short-circuit detection circuit as described in claim 2, characterized in that, The first comparison branch includes a first comparator and a first pull-up resistor, and the second comparison branch includes a second comparator and a second pull-up resistor; wherein, the non-inverting input terminals of the first comparator and the second comparator are respectively connected to the common junction between the first diode and the second diode, the inverting input terminal of the first comparator is connected to the first reference voltage, the inverting input terminal of the second comparator is connected to the second reference voltage, the first output terminal of the first comparator is connected to the first power supply, the second output terminal of the first comparator is grounded, the third output terminal of the first comparator and one end of the first pull-up resistor are respectively connected to the timing circuit, the other end of the first pull-up resistor is connected to the second power supply, the output terminal of the second comparator and one end of the second pull-up resistor are respectively connected to the timing circuit, and the other end of the second pull-up resistor is connected to the second power supply; The first comparison branch is specifically used to compare the second voltage with the first reference voltage through the first comparator, and output the first sub-signal to the timing circuit through the third output terminal according to the comparison result; wherein, when the second voltage is greater than the first reference voltage, the first sub-signal remains at a high level; when the second voltage is less than the first reference voltage, the first sub-signal changes from a high level to a low level; The second comparison branch is specifically used to compare the second voltage with the second reference voltage through the second comparator, and output the second sub-signal to the timing circuit according to the comparison result; wherein, when the second voltage is greater than the second reference voltage, the second sub-signal remains at a high level; when the second voltage is less than the second reference voltage, the second sub-signal changes from a high level to a low level.

4. The IGBT short-circuit detection circuit as described in claim 3, characterized in that, The first timing branch includes a first NOT gate, a third diode, a third resistor, and a first capacitor; wherein, the first input terminal of the OR gate, one end of the first capacitor, and the anode of the third diode are respectively connected to one end of the third resistor, the other end of the first capacitor is grounded, the other end of the third resistor and the cathode of the third diode are respectively connected to the output terminal of the first NOT gate, and the input terminal of the first NOT gate is connected to the third output terminal of the first comparator. The second timing branch includes a second NOT gate, a fourth diode, a fourth resistor, and a second capacitor; wherein, the second input terminal of the OR gate, one end of the second capacitor, and the anode of the fourth diode are respectively connected to one end of the fourth resistor, the other end of the second capacitor is grounded, the other end of the fourth resistor and the cathode of the fourth diode are respectively connected to the output terminal of the second NOT gate, and the input terminal of the second NOT gate is connected to the output terminal of the second comparator. The first timing branch is specifically used to charge the first capacitor through the third resistor to increase the terminal voltage of the first capacitor when the first sub-signal changes from high level to low level and the output of the first NOT gate changes from low level to high level; and to discharge the first capacitor through the third diode to decrease the terminal voltage of the first capacitor when the first sub-signal changes from low level to high level and the output of the first NOT gate changes from high level to low level; wherein, the terminal voltage of the first capacitor is the third voltage; The second timing branch is specifically used to charge the second capacitor through the fourth resistor to increase the terminal voltage of the second capacitor when the second sub-signal changes from high level to low level and the output of the second NOT gate changes from low level to high level; and to discharge the second capacitor through the fourth diode to decrease the terminal voltage of the second capacitor when the second sub-signal changes from low level to high level and the output of the second NOT gate changes from high level to low level; wherein, the terminal voltage of the second capacitor is the fourth voltage; Specifically, the OR gate is used to output a second signal that remains low and indicates that the IGBT under test has not short-circuited when the total duration of the first sub-signal and the second sub-signal being at a low level is less than the preset duration and the sum of the third voltage and the fourth voltage is less than the switching threshold voltage of the OR gate; and to output a second signal that changes from low to high and indicates that the IGBT under test has short-circuited when the total duration of the first sub-signal and the second sub-signal being at a low level is greater than or equal to the preset duration and the sum of the third voltage and the fourth voltage is greater than or equal to the switching threshold voltage of the OR gate.

5. An IGBT short-circuit detection method, applied to an IGBT short-circuit detection circuit, characterized in that, The IGBT short-circuit detection circuit includes a sampling circuit, a comparison circuit, and a timing circuit; wherein, the timing circuit is connected to the comparison circuit, the comparison circuit is connected to the sampling circuit, and the sampling circuit is used to connect the stray inductance between the auxiliary emitter and the power emitter in the IGBT under test; the sampling circuit includes a voltage divider branch; the comparison circuit includes a first comparison branch and a second comparison branch; the timing circuit includes a first timing branch, a second timing branch, and an OR gate; The IGBT short-circuit detection method includes: The voltage divider branch acquires the first voltage of the stray inductor, divides the first voltage to obtain a second voltage, and outputs the second voltage to the comparator circuit; the comparator circuit includes a first comparator branch and a second comparator branch; The first comparison branch compares the second voltage with a preset first reference voltage, and outputs a first sub-signal to the timing circuit based on the comparison result; The second comparison branch compares the second voltage with a preset second reference voltage, and outputs a second sub-signal to the timing circuit based on the comparison result; The first reference voltage and the second reference voltage have the following relationship: Wherein, Vref1 is the voltage value of the first reference voltage, and Vref2 is the voltage value of the second reference voltage; The first timing branch outputs an increased third voltage to the OR gate when the first sub-signal is at a preset level, and outputs a decreased third voltage to the OR gate when the first sub-signal is at other levels. The second timing branch outputs an increased fourth voltage to the OR gate when the second sub-signal is at the preset level, and outputs a decreased fourth voltage to the OR gate when the second sub-signal is at other level. The OR gate outputs a second signal indicating that the IGBT under test has short-circuited when the sum of the third voltage and the fourth voltage is greater than or equal to the switching threshold voltage of the OR gate, and outputs a second signal indicating that the IGBT under test has not short-circuited when the sum of the third voltage and the fourth voltage is less than the switching threshold voltage of the OR gate. Wherein, when the total duration of the first sub-signal and the second sub-signal being in the preset level state is greater than or equal to the preset duration, the sum of the third voltage and the fourth voltage is greater than or equal to the switching threshold voltage of the OR gate; when the total duration of the first sub-signal and the second sub-signal being in the preset level state is less than the preset duration, the sum of the third voltage and the fourth voltage is less than the switching threshold voltage of the OR gate; the total duration of the first sub-signal and the second sub-signal being in the preset level state is the duration of the rising edge of the current flowing through the stray inductor.

6. An IGBT short-circuit protection circuit, characterized in that, It includes a control circuit and an IGBT short-circuit detection circuit as described in any one of claims 1-4; wherein the timing circuit is connected to the control circuit, and the control circuit is used to connect the IGBT under test; The control circuit is used to turn on the IGBT under test or turn off the IGBT under test according to the second signal.

7. An IGBT short-circuit protection method, applied to an IGBT short-circuit protection circuit, characterized in that, The IGBT short-circuit protection circuit includes a control circuit and an IGBT short-circuit detection circuit as described in any one of claims 1-4; wherein the timing circuit is connected to the control circuit, and the control circuit is used to connect the IGBT under test; The IGBT short-circuit protection method includes: The sampling circuit acquires the voltage of the stray inductor; The comparison circuit compares the voltage of the stray inductor with a preset reference voltage and outputs a first signal based on the comparison result. The timing circuit outputs a second signal indicating whether the IGBT under test has short-circuited, based on the duration of the first signal being at a preset level. The duration of the first signal being at the preset level is the duration of the rising edge of the current flowing through the stray inductor. The control circuit turns on the IGBT under test or turns off the IGBT under test according to the second signal.

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