IGBT soft-shutdown protection circuit, IGBT drive circuit and electrical equipment

Abstract

The present invention relates to an IGBT soft-off protection circuit, an IGBT drive circuit, and an electrical device. The IGBT soft-off protection circuit comprises: a high-impedance circuit and a low-impedance circuit connected in parallel between an IGBT module and ground; a detection module for detecting whether a short circuit or overcurrent occurs in the IGBT module and outputting a control signal based on the detection result; and a switching module for, based on the control signal, connecting the IGBT module to the high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, and connecting the IGBT module to the low-impedance circuit when the IGBT module is operating normally, thereby reducing the peak current flowing through the IGBT module. The technical solution provided by the present invention prevents a sharp decrease in the current flowing through the IGBT module by connecting the IGBT module to the high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, thereby reducing voltage spikes, preventing damage to the IGBT module, and extending the service life of the IGBT module.

Description

Technical Field

[0001] The present invention relates to the technical field of IGBTs, and in particular to an IGBT soft-shutdown protection circuit, an IGBT drive circuit, and electrical equipment. Background Art

[0002] IGBT (Insulated Gate Bipolar Transistor), an insulated gate bipolar transistor, is a composite fully controlled voltage-driven power semiconductor device composed of BJT (bipolar junction transistor) and MOS (insulated gate field effect transistor). It has the advantages of both the high input impedance of MOSFET and the low on-state voltage drop of GTR. It is now widely used in machine tools, robots and other fields.

[0003] The IGBT working area is divided into three parts

[0004] 1. Cut-off region: The voltage between CE is less than 0.7V, the PN junction on the back of the IGBT is cut off, and no current flows.

[0005] 2. Saturation region: The voltage between CE is greater than 0.7V, the current begins to flow, and the voltage between CE increases linearly with the increase of collector current. This is the desired working state of IGBT.

[0006] 3. Amplification Region: As the voltage between the collector and collector electrodes continues to rise, the current increases further. After reaching a certain critical point, the collector and collector electrodes voltage increases rapidly, while the collector current does not increase accordingly. At this point, the IGBT is said to have exited the saturation region.

[0007] In practical applications, desaturation typically occurs when the device is short-circuited. At this point, the CE voltage rises to the bus voltage, and the current is typically four times the rated current (see the device datasheet). This causes an abnormal increase in power and a sharp rise in junction temperature. Failure to shut down the device in a timely manner can lead to device burnout. Most IGBTs have a certain short-circuit withstand capability, generally within 10µs. Refer to the product datasheet for details.

[0008] Because the device current is very large in the desaturation state, if the IGBT is turned off without restriction, a large di / dt will be generated, and a high CE voltage will be induced on the parasitic inductance of the loop. If this voltage is higher than the rated voltage of the device, the IGBT may be damaged.

[0009] Figure 1 This is an IGBT desaturation detection circuit used in the prior art. Figure 1When desaturation is detected in the IGBT, that is, the voltage Va at point a is greater than the reference voltage Vref, the main control chip MCU turns off the IGBT, protecting the IGBT through the IGBT desaturation detection circuit. However, due to the large voltage spike generated during shutdown, the shutdown time must be slowed down, which can easily damage the IGBT and shorten its service life. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide an IGBT soft shutdown protection circuit, an IGBT drive circuit and an electrical device to solve the problem in the prior art that when the IGBT module is short-circuited or overcurrent occurs, it is forced to shut down and a large voltage spike is generated, causing damage to the IGBT module.

[0011] According to a first aspect of an embodiment of the present invention, there is provided an IGBT soft shutdown protection circuit, comprising:

[0012] A high-impedance loop and a low-impedance loop connected in parallel are connected between the IGBT module and the ground;

[0013] A detection module is used to detect whether the IGBT module is short-circuited or over-current occurs, and output a control signal according to the detection result;

[0014] The switch switching module is used to connect the IGBT module to the high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, and to connect the IGBT module to the low-impedance circuit when the IGBT module is operating normally, so as to reduce the peak current flowing through the IGBT module.

[0015] Preferably, the high impedance loop comprises: an inductor, a resistor, or a combination of an inductor and a resistor; and / or,

[0016] The low-impedance loop includes a switching circuit, which is a combination of one or more of the following switching elements:

[0017] Bidirectional thyristor, transistor, MOS tube.

[0018] Preferably, if the IGBT module includes multiple IGBTs, and every two IGBTs form a phase inverter circuit,

[0019] The detection module includes:

[0020] At least one detection branch, each detection branch is connected to a phase inverter circuit;

[0021] The logic judgment circuit is connected to the detection branch and is used to output a control signal according to the detection result of the detection branch.

[0022] Preferably, each of the detection branches includes:

[0023] a diode, the anode of which is connected to the logic judgment circuit, and the cathode of which is connected to the collector of the IGBT;

[0024] a constant current source connected to the positive electrode of the diode;

[0025] The energy storage capacitor is connected to the positive electrode of the diode.

[0026] Preferably, the logic judgment circuit includes:

[0027] At least one first AND gate, connected to the detection branch, configured to output a high-level signal when a through short circuit or overcurrent occurs in the upper and lower bridges of the inverter circuit connected to the first AND gate;

[0028] A NOR gate connected to the AND gate, configured to output a low-level signal when a through short circuit or overcurrent occurs in the upper and lower bridges of any phase inverter circuit;

[0029] a second AND gate, one end of which is connected to the load controller and the other end of which is connected to the NOR gate, for outputting a high-level control signal when both the load controller and the NOR gate output high-level signals; and for outputting a low-level control signal when either the load controller or the NOR gate outputs a low-level signal;

[0030] The load controller outputs a high-level signal when starting the IGBT module and outputs a low-level signal when shutting down the IGBT module.

[0031] Preferably, the switch switching module is connected to the control end of the low impedance loop;

[0032] The switch switching module is specifically used to turn on when the control signal is a high-level signal, and control the low-impedance loop to turn on, so as to connect the low-impedance loop to the IGBT module and the ground; and to turn off when the control signal is a low-level signal, and control the low-impedance loop to turn off, so as to connect the high-impedance loop to the IGBT module and the ground.

[0033] Preferably, the switch switching module is an optocoupler isolation switch circuit.

[0034] Preferably, the control end of the low-impedance loop is provided with a current-limiting resistor with adjustable resistance;

[0035] The current limiting resistor is used to adjust the opening and closing time of the low-impedance circuit.

[0036] According to a second aspect of an embodiment of the present invention, there is provided an IGBT driving circuit, comprising:

[0037] The above-mentioned IGBT soft shutdown protection circuit.

[0038] According to a third aspect of an embodiment of the present invention, there is provided an electric device, including:

[0039] The above-mentioned IGBT driving circuit.

[0040] The technical solutions provided by the embodiments of the present invention may have the following beneficial effects:

[0041] By connecting the IGBT module to a high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, the current flowing through the IGBT module is prevented from decreasing sharply, thereby reducing the voltage spike, preventing the IGBT module from being damaged, and extending the service life of the IGBT module.

[0042] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0044] Figure 1 is a circuit schematic diagram of an IGBT desaturation detection circuit according to background technology;

[0045] Figure 2 is a principle block diagram of an IGBT soft-turn-off protection circuit according to an exemplary embodiment;

[0046] Figures 3A-3B is a circuit principle diagram of a detection branch according to an exemplary embodiment;

[0047] Figure 4 The figure is a flow chart showing a method for controlling an IGBT soft-turn-off protection circuit according to an exemplary embodiment. DETAILED DESCRIPTION

[0048] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent like or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention, as detailed in the appended claims.

[0049] Example 1

[0050] Figure 2 FIG. 1 is a circuit schematic diagram of an IGBT soft-turn-off protection circuit according to an exemplary embodiment. Figure 2 As shown, the circuit includes:

[0051] The high impedance loop 11 and the low impedance loop 12 are connected in parallel to the IGBT module (eg Figure 2 The IGBT module is composed of six IGBTs, including: G1 to G6) and ground;

[0052] The detection module 13 is used to detect whether the IGBT module is short-circuited or over-current occurs, and output a control signal according to the detection result;

[0053] The switch switching module 14 is used to connect the IGBT module to the high-impedance circuit 11 when the IGBT module is short-circuited or overcurrent occurs, and to connect the IGBT module to the low-impedance circuit 12 when the IGBT module is operating normally, so as to reduce the peak current flowing through the IGBT module.

[0054] It can be understood that the technical solution provided in this embodiment connects the IGBT module to a high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, thereby preventing the current flowing through the IGBT module from decreasing sharply, thereby reducing the voltage spike, preventing the IGBT module from being damaged, and extending the service life of the IGBT module.

[0055] During the shutdown process of the IGBT module, directly reducing the shutdown time required for the IGBT module will cause excessive spike voltage. If switching to a high-impedance circuit, the current will not drop rapidly, but will start to drop at the moment the IGBT module short circuit is detected. After the IGBT module is quickly shut down, the current has already dropped by a large part, which reduces the current reduction speed and thus reduces the voltage spike.

[0056] Understandably, when an IGBT module is short-circuited or experiencing overcurrent, the current flowing through it can be very high. IGBT modules generally have an overcurrent timer. The more the current exceeds its maximum current rating, the shorter this timer becomes. If this timer is exceeded, the IGBT module will be damaged. If the off-time is too long, the IGBT will remain in an overcurrent state for a prolonged period, potentially causing burnout.

[0057] Controlling the off-time is generally done by changing the gate resistance of the IGBT module. Reducing the gate resistance can shorten the off-time. However, the instantaneous decrease in current can cause a large voltage spike. If this exceeds the withstand voltage of the IGBT module, it may also damage the IGBT module. Therefore, the off-time cannot be too short.

[0058] The technical solution provided in this embodiment connects the IGBT module to a high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs. The current flowing through the IGBT module does not decrease sharply, so a shorter shutdown time can be used. While ensuring the reduction of voltage spikes, it also solves the problem of damage to the IGBT module due to excessively long shutdown time.

[0059] In specific practice, the high impedance loop 11 may include: an inductor, a resistor, or a combination circuit of an inductor and a resistor; and / or,

[0060] The low-impedance loop 12 may include: a switching circuit, wherein the switching circuit is a combination of one or more of the following switching elements, including:

[0061] Bidirectional thyristor, transistor, MOS tube.

[0062] If the IGBT module includes multiple IGBTs, and every two IGBTs form a phase inverter circuit,

[0063] The detection module 13 includes:

[0064] At least one detection branch 131, each detection branch 131 is connected to a phase inverter circuit;

[0065] The logic judgment circuit 132 is connected to the detection branch 131 and is used to output a control signal according to the detection result of the detection branch 131 .

[0066] See also Figure 2 , the IGBT module is a three-phase bridge inverter module, including six IGBTs (such as Figure 2 G1 to G6 in the PCR test);

[0067] Every two IGBTs form a one-phase inverter circuit, which is used to provide a one-phase AC input for the load motor M.

[0068] The detection module 13 includes:

[0069] Six detection branches 131, each detection branch 131 is connected to a phase inverter circuit;

[0070] The logic judgment circuit 132 is connected to the detection branch 131 and is used to output a control signal according to the detection result of the detection branch 131 .

[0071] See also Figure 3A-3B Each detection branch 131 includes:

[0072] A diode D1, whose anode is connected to the logic judgment circuit 132 and whose cathode is connected to the collector of the IGBT G1;

[0073] A constant current source DC is connected to the positive electrode of the diode D1;

[0074] The energy storage capacitor C1 is connected to the positive electrode of the diode D1.

[0075] See also Figure 3A , Figure 3A This is the current flow diagram of the detection branch when G1 is working normally. When G1 is working normally, diode D1 is turned on, and the current output by the constant current source DC flows into the ground through D1 and G1. The detection branch outputs a low-level signal through diode D1;

[0076] See also Figure 3B , Figure 3B The current flow diagram of the detection branch when G1 is short-circuited or overcurrent occurs. At this time, the voltage at the cathode of diode D1 is extremely high, and no forward voltage drop can be formed between the positive and negative electrodes of diode D1, causing it to be cut off. The current output by the constant current source DC charges the capacitor, and during the charging process, the voltage at the positive electrode of D1 increases, causing the detection branch to output a high-level signal.

[0077] See also Figure 2 Preferably, the logic judgment circuit 132 includes:

[0078] At least one first AND gate, connected to the detection branch, configured to output a high-level signal when a through short circuit or overcurrent occurs in the upper and lower bridges of the inverter circuit connected to the first AND gate;

[0079] A NOR gate connected to the AND gate, configured to output a low-level signal when a through short circuit or overcurrent occurs in the upper and lower bridges of any phase inverter circuit;

[0080] a second AND gate, one end of which is connected to the load controller and the other end of which is connected to the NOR gate, for outputting a high-level control signal when both the load controller and the NOR gate output high-level signals; and for outputting a low-level control signal when either the load controller or the NOR gate outputs a low-level signal;

[0081] The load controller outputs a high-level signal when starting the IGBT module and outputs a low-level signal when shutting down the IGBT module.

[0082] See also Figure 2 The diodes of the first detection branch are D1 and D4, the diodes of the second detection branch are D2 and D5, and the diodes of the third detection circuit are D3 and D6.

[0083] When the IGBT module is working normally, only one of the two IGBTs in one phase inverter circuit will be turned on and the other one will be turned off. Figure 2 G1 is on, G4 is off; G5 is on, G2 is off; G6 is on, G3 is off, diode D1 is on, constant current source ( Figure 2 The current of the constant current source (DC) in FIG3 is not shown in FIG3 , and flows through D1, G1, the load motor, G6 and the ground in sequence. The voltage drop of the IGBT is very low. When G2 desaturates, G1 and G4 form a path, the voltage drop increases sharply, D1 and D4 are cut off, and the constant current source ( Figure 2 The current output by the energy storage capacitor (not shown) can only be Figure 2 (not shown in the figure, see the energy storage capacitor C1 in Figure 3) is charged. When the voltage on the energy storage capacitor exceeds the threshold, a high level signal is sent to the AND gate connected to the first detection branch, indicating that a direct short circuit or overcurrent occurs in the upper and lower bridges of the inverter circuit of the current phase.

[0084] The principles for detecting whether short circuit or overcurrent occurs in the inverter circuits of other phases are the same and will not be described in detail here.

[0085] In specific practice, the switch switching module 14 is connected to the control end of the low impedance loop 12;

[0086] The switch switching module 14 is specifically configured to be turned on when the control signal is a high-level signal, and to control the low-impedance loop 12 to be turned on, so as to connect the low-impedance loop 12 to between the IGBT module and the ground; and to be turned off when the control signal is a low-level signal, and to control the low-impedance loop 12 to be turned off, so as to connect the high-impedance loop 11 to between the IGBT module and the ground.

[0087] In specific practice, the control end of the low impedance loop 12 is provided with a current limiting resistor with adjustable resistance (not shown in the drawings);

[0088] The current limiting resistor is used to adjust the opening and closing time of the low-impedance circuit 12.

[0089] Taking the low-impedance circuit 12 as a bidirectional thyristor as an example, increasing the bidirectional thyristor's off-current can be achieved by changing the bidirectional thyristor's gate resistance. Reducing the resistance increases the current. When the off-current increases, the PN junction between the bidirectional thyristor's gate and ground turns off more quickly, and the entire bidirectional thyristor turns off more quickly.

[0090] See also Figure 2 Preferably, the switch switching module 14 is an optocoupler isolation switch circuit.

[0091] It can be understood that the optocoupler isolation switch circuit can improve the anti-interference ability of the circuit and improve the reliability and stability of the circuit.

[0092] Figure 4 FIG. 1 is a flow chart showing a method for controlling an IGBT soft-turn-off protection circuit according to an exemplary embodiment. Figure 4 As shown, the method includes:

[0093] When the load controller MCU outputs a high-level signal OE=1 when starting the IGBT module, and when the IGBT module is working normally, the NOR gate outputs a high-level control signal Y4=1. At this time, when OE=1 and Y4=1 are satisfied, the detection module outputs a high-level control signal, the optocoupler isolation switch circuit is turned on, the bidirectional thyristor is turned on, the high-impedance loop is short-circuited, and the low-impedance loop is connected between the IGBT module and the ground.

[0094] When the load controller MCU outputs a high-level signal OE=1 when starting the IGBT module, when the IGBT module is short-circuited or overcurrent occurs, the NOR gate outputs a low-level control signal Y4=0. At this time, the detection module outputs a low-level control signal, the optocoupler isolation switch circuit is not conducting, the bidirectional thyristor is not conducting, and the high-impedance loop is connected between the IGBT module and the ground; then the load controller MCU turns off the IGBT module and outputs a low-level signal OE=0, the optocoupler isolation switch circuit is not conducting, the bidirectional thyristor is not conducting, until the load controller MCU restarts the IGBT module, when OE=1 and Y4=1, the low-impedance loop is re-connected between the IGBT module and the ground, otherwise the high-impedance loop is always connected between the IGBT module and the ground, which can better protect the IGBT module.

[0095] It can be understood that the technical solution provided in this embodiment connects the IGBT module to a high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, thereby preventing the current flowing through the IGBT module from decreasing sharply, thereby reducing the voltage spike, preventing the IGBT module from being damaged, and extending the service life of the IGBT module.

[0096] Example 2

[0097] According to an exemplary embodiment, an IGBT driving circuit includes:

[0098] The above-mentioned IGBT soft shutdown protection circuit.

[0099] It can be understood that the technical solution provided in this embodiment includes the above-mentioned IGBT soft-shutdown protection circuit, and the above-mentioned IGBT soft-shutdown protection circuit connects the IGBT module to a high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, thereby preventing the current flowing through the IGBT module from decreasing sharply, thereby reducing the voltage spike, preventing the IGBT module from being damaged, and extending the service life of the IGBT module.

[0100] Example 3

[0101] According to an exemplary embodiment, an electric device includes:

[0102] The above-mentioned IGBT driving circuit.

[0103] It can be understood that the technical solution provided in this embodiment includes the above-mentioned IGBT soft-shutdown protection circuit, and the above-mentioned IGBT soft-shutdown protection circuit connects the IGBT module to a high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, thereby preventing the current flowing through the IGBT module from decreasing sharply, thereby reducing the voltage spike, preventing the IGBT module from being damaged, and extending the service life of the IGBT module.

[0104] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0105] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is at least two.

[0106] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

[0107] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0108] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0109] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

[0110] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0111] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0112] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An IGBT soft-off protection circuit, characterized in that: include: A high-impedance loop and a low-impedance loop connected in parallel are connected between the IGBT module and the ground; The high impedance loop includes: an inductor, a resistor, or a combination of an inductor and a resistor; and / or, The low-impedance loop includes a switching circuit, which is a combination of one or more of the following switching elements: Bidirectional thyristor, transistor, MOS tube; A detection module is used to detect whether the IGBT module is short-circuited or over-current occurs, and output a control signal according to the detection result; If the IGBT module includes multiple IGBTs, and every two IGBTs form a phase inverter circuit, The detection module includes: At least one detection branch, each detection branch is connected to a phase inverter circuit; a logic judgment circuit, connected to the detection branch, and configured to output a control signal according to a detection result of the detection branch; Each of the detection branches includes: a diode, the anode of which is connected to the logic judgment circuit, and the cathode of which is connected to the collector of the IGBT; a constant current source connected to the positive electrode of the diode; an energy storage capacitor connected to the positive electrode of the diode; a switch switching module, configured to connect the IGBT module to the high-impedance circuit when the IGBT module is short-circuited or overcurrent occurs, and to connect the IGBT module to the low-impedance circuit when the IGBT module is operating normally, so as to reduce a peak current flowing through the IGBT module; The logic judgment circuit includes: At least one first AND gate, connected to the detection branch, configured to output a high-level signal when a through short circuit or overcurrent occurs in the upper and lower bridges of the inverter circuit connected to the first AND gate; A NOR gate connected to the first AND gate, configured to output a low-level signal when a through short circuit or overcurrent occurs in the upper and lower bridges of any phase inverter circuit; a second AND gate, one end of which is connected to the load controller and the other end of which is connected to the NOR gate, for outputting a high-level control signal when both the load controller and the NOR gate output high-level signals; and for outputting a low-level control signal when either the load controller or the NOR gate outputs a low-level signal; The load controller outputs a high-level signal when starting the IGBT module and outputs a low-level signal when shutting down the IGBT module.

2. The IGBT soft-turn-off protection circuit according to claim 1, characterized in that: The switch switching module is connected to the control end of the low impedance loop; The switch switching module is specifically used to turn on when the control signal is a high-level signal, and control the low-impedance loop to turn on, so as to connect the low-impedance loop to the IGBT module and the ground; and to turn off when the control signal is a low-level signal, and control the low-impedance loop to turn off, so as to connect the high-impedance loop to the IGBT module and the ground.

3. The IGBT soft-turn-off protection circuit according to claim 2, characterized in that: The switch switching module is an optocoupler isolation switch circuit.

4. The IGBT soft-turn-off protection circuit according to claim 2, characterized in that: The control end of the low-impedance loop is provided with a current-limiting resistor with adjustable resistance; The current limiting resistor is used to adjust the opening and closing time of the low-impedance circuit.

5. An IGBT driving circuit, characterized in that: include: The IGBT soft shutdown protection circuit according to any one of claims 1 to 4.

6. An electrical device, characterized in that: include: The IGBT driving circuit according to claim 5.

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