Control circuit, bridge arm circuit and bridge arm straight-through test circuit of IGBT (Insulated Gate Bipolar Translator) device
By introducing magnetic devices into the control circuit of IGBT devices, the IGBT tube damage caused by high-frequency noise and resonance in the bridge arm straight-through test is solved, and the stability of the test waveform and the safety of the IGBT device are achieved.
Patent Information
- Application Number
- CN202421504414.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-27
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2034-06-27
AI Technical Summary
In the bridge arm through test of IGBT tube, the parasitic inductor and capacitor in the control circuit produce frequency of gigahertz resonance, resulting in severe oscillation of the test waveform, which easily leads to damage to the IGBT tube.
In the control circuit of the IGBT device, magnetic devices, including magnetic beads, capacitors and gate resistors, are introduced into the control circuit of the IGBT device. The magnetic device and the capacitor are connected in series and parallel between the gate and emitter of the IGBT device to absorb high-frequency noise and suppress resonance between the capacitor and the parasitic inductance of the IGBT device.
The magnetic device effectively absorbs high-frequency noise in the control circuit, suppresses the resonance between the capacitor and the parasitic inductor of the IGBT device, avoids damage to the IGBT device, and ensures the waveform stability of the bridge arm through test.
Smart Images
Figure CN222915891U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of circuits, and particularly relates to a control circuit, a bridge arm circuit and a bridge arm direct connection test circuit of an IGBT device. Background Art
[0002] When performing a double-pulse test on an IGBT (Insulated Gate Bipolar Transistor), affected by parasitic signals in the test loop, a large spike voltage will be introduced, which is likely to cause damage to the IGBT. Especially for a circuit structure including upper and lower bridge arm IGBTs, when measuring the switching characteristics of the lower bridge arm IGBT, due to the oscillation caused by the on-off of the IGBT, the actual gate voltage of the upper bridge arm IGBT will exceed the withstand voltage value of the IGBT, and the IGBT may be damaged under long-term working conditions. In related technologies, by adding a capacitor in the control circuit of the IGBT and making the capacitor in parallel with the gate and emitter of the IGBT, the spike of the gate voltage can be well suppressed, and the gate voltage exceeding the withstand voltage value of the IGBT can be avoided. However, for the control circuit after adding the capacitor, when the IGBT performs a bridge arm direct connection test to accurately evaluate the working state, tolerance ability and effectiveness of the protection mechanism of the IGBT under the short-circuit condition, the parasitic inductance in the control circuit will resonate with the capacitor at a frequency of up to gigahertz, resulting in severe oscillation of the waveform of the bridge arm direct connection test, multiple voltage spikes and high-frequency oscillation, which is likely to cause damage to the IGBT. Summary of the Invention
[0003] In view of this, the purpose of the utility model is to provide a control circuit, a bridge arm circuit and a bridge arm direct connection test circuit of an IGBT device, so as to suppress high-frequency noise and spike interference through a magnetic device and avoid damage to the IGBT device during the bridge arm direct connection test.
[0004] In a first aspect, an embodiment of the utility model provides a control circuit of an IGBT device. The control circuit includes a magnetic device, a capacitor and a gate resistor; the first end of the gate resistor is connected to the gate terminal of the IGBT device, and the second end of the gate resistor is connected to a pulse voltage; the first end of the magnetic device is connected to the gate terminal of the IGBT device, the second end of the magnetic device is connected to the first end of the capacitor, and the second end of the capacitor is connected to the emitter terminal of the IGBT device.
[0005] Further, the above magnetic device includes a magnetic bead.
[0006] Further, the above control circuit further includes a first resistor, and the first resistor is connected in parallel between the gate terminal and the emitter terminal of the IGBT device.
[0007] Further, the above control circuit further includes a second resistor, and the second resistor is connected in parallel with the magnetic device.
[0008] In a second aspect, an embodiment of the present invention provides a bridge arm circuit of an IGBT device. The bridge arm circuit includes at least one bridge arm branch; the bridge arm branch is formed by connecting multiple IGBT devices in series; each of the IGBT devices is equipped with the control circuit of the above IGBT device.
[0009] In a third aspect, an embodiment of the present invention provides a bridge arm direct conduction test circuit. The bridge arm direct conduction test circuit includes a power supply module and a bus circuit; the power supply module is used to supply power to the bus circuit; the positive and negative terminals of the bus circuit are respectively connected to both ends of a bridge arm branch in the bridge arm circuit of the IGBT device; the bridge arm circuit of the IGBT device is the above-mentioned bridge arm circuit of the IGBT device; in the bridge arm branch, the collector terminal and the emitter terminal of the first IGBT device are kept in a connected state; a pulse signal is input to the second IGBT device.
[0010] Furthermore, the above power supply module includes a voltage regulator and a rectifying device.
[0011] Furthermore, the above bus circuit includes a bus capacitor. The positive pole of the bus capacitor is connected to the collector terminal of the first IGBT device; the negative pole of the bus capacitor is connected to the emitter terminal of the second IGBT device.
[0012] Furthermore, the above bridge arm direct conduction test circuit further includes a contactor; the contactor is connected between the power supply module and the bus circuit.
[0013] Furthermore, the above bridge arm direct conduction test circuit further includes a test module, and the test module includes at least one of an isolation probe, a low-voltage probe, and a Rogowski coil.
[0014] The embodiments of the present invention bring the following beneficial effects:
[0015] The above control circuit, bridge arm circuit, and bridge arm direct conduction test circuit of the IGBT device. Among them, the control circuit includes a magnetic device, a capacitor, and a gate resistor; the first end of the gate resistor is connected to the gate terminal of the IGBT device, and the second end of the gate resistor is connected to a pulse voltage; the first end of the magnetic device is connected to the gate terminal of the IGBT device, the second end of the magnetic device is connected to the first end of the capacitor, and the second end of the capacitor is connected to the emitter terminal of the IGBT device.
[0016] In the control circuit of the IGBT device, the capacitor and the magnetic device are connected in series and then connected in parallel with the gate terminal and the emitter terminal of the IGBT device. When the IGBT tube conducts a bridge arm direct conduction test, the magnetic device can effectively absorb the high-frequency noise in the control circuit, suppress the resonance phenomenon between the capacitor and the parasitic inductance of the IGBT device, and avoid damage to the IGBT device.
[0017] Other features and advantages of the present utility model will be described in the subsequent description, and in part will be obvious from the description, or will be understood by implementing the present utility model. The objectives and other advantages of the present utility model are achieved and obtained by the structures specifically pointed out in the description, claims and drawings.
[0018] In order to make the above objectives, features and advantages of the present utility model more obvious and understandable, the following specifically provides preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows. Brief Description of the Drawings
[0019] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present utility model. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0020] Figure 1 Schematic diagram of the control circuit of the first IGBT device provided by the embodiment of the present utility model;
[0021] Figure 2 Schematic diagram of the control circuit of the second IGBT device provided by the embodiment of the present utility model;
[0022] Figure 3 Schematic diagram of the control circuit of the third IGBT device provided by the embodiment of the present utility model;
[0023] Figure 4 Schematic diagram of the bridge arm circuit of an IGBT device provided by the embodiment of the present utility model;
[0024] Figure 5 Schematic diagram of the first bridge arm direct conduction test circuit provided by the embodiment of the present utility model;
[0025] Figure 6 Schematic diagram of the first bridge arm direct conduction test circuit provided by the embodiment of the present utility model;
[0026] Figure 7 Schematic diagram of the waveform of the first bridge arm direct conduction test provided by the embodiment of the present utility model;
[0027] Figure 8 Schematic diagram of the waveform of the first bridge arm direct conduction test provided by the embodiment of the present utility model. Detailed Embodiments
[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.
[0029] In the related art, by adding a capacitor to the control circuit of the IGBT transistor, and making the capacitor in parallel with the gate and emitter of the IGBT, it is possible to well suppress the glitch spikes of the gate voltage during the double-pulse test, and avoid the gate voltage exceeding the breakdown voltage of the IGBT transistor. However, when using this control circuit to conduct a shoot-through test on the IGBT transistor to verify whether parameters such as the turn-off voltage between the collector terminal and the emitter terminal of the IGBT transistor and the gate voltage of the IGBT meet the requirements of the device specification sheet under short-circuit conditions, and whether the protection mechanism of the IGBT transistor is effective, the parasitic inductance in the control circuit will resonate with the capacitor at a frequency of up to gigahertz, resulting in severe oscillation of the shoot-through test waveform. The voltage spikes and high-frequency oscillations generated by the oscillation are likely to cause damage to the IGBT transistor. To solve this problem, in the related art, the severe oscillation problem of the shoot-through test waveform can be solved by adding a resistor in the control circuit or removing the capacitor in the circuit. However, simply adding a resistor may affect the turn-on and turn-off speed of the IGBT transistor and increase the switching loss; if the capacitor in the control circuit is removed to eliminate the oscillation, it will cause the problem of the gate voltage exceeding the limit under the double-pulse test.
[0030] Based on this, the present embodiment provides a control circuit, a shoot-through circuit, and a shoot-through test circuit for an IGBT device, which can be applied to the shoot-through test scenario of the IGBT device.
[0031] Figure 1 A control circuit for an IGBT device is provided. The control circuit includes a magnetic device, a capacitor, and a gate resistor; the first end of the gate resistor is connected to the gate terminal of the IGBT device, and the second end of the gate resistor is connected to a pulse voltage; the first end of the magnetic device is connected to the gate terminal of the IGBT device, the second end of the magnetic device is connected to the first end of the capacitor, and the second end of the capacitor is connected to the emitter terminal of the IGBT device.
[0032] The above magnetic device has resistivity and permeability, and can be equivalent to a series-connected resistor and inductor. The equivalent resistance value and inductance value of the magnetic device will vary with frequency, and it can exhibit different impedance characteristics at different frequencies. In the low-frequency state, the magnetic device is equivalent to a resistor with an extremely low resistance value. In the high-frequency state, the magnetic device can generate a certain resistance value and inductance value to absorb high-frequency signals in the control circuit. The above magnetic device includes a magnetic bead. The above gate resistor is a resistor used to control the on-off speed of the IGBT device. Generally, the smaller the resistance value of the gate resistor, the faster the on-off speed of the IGBT device, and the switching between the on state and the off state of the IGBT device can be completed faster. The above pulse voltage is used to control the on-off state of the collector terminal and the emitter terminal in the IGBT device. When the pulse voltage exceeds the preset voltage threshold, the IGBT starts to conduct, and the current can flow from the collector terminal to the emitter terminal of the IGBT device; when the pulse voltage is below the preset voltage threshold, the collector terminal and the emitter terminal of the IGBT device are in the off state.
[0033] Here, as Figure 1 shown, the gate terminal of the IGBT device is connected to one end of the gate resistor, the other end of the gate resistor is connected to the pulse voltage, the gate terminal of the IGBT device is also connected to one end of the magnetic device, and the other end of the magnetic device is connected to a capacitor. After the capacitor and the magnetic device are connected in series, they are connected in parallel between the gate terminal and the emitter terminal of the IGBT device.
[0034] For the control circuit of the IGBT device, after the capacitor and the magnetic device are connected in series and then connected in parallel between the gate terminal and the emitter terminal of the IGBT device, when the IGBT tube conducts a bridge arm direct connection test, the high-frequency noise in the control circuit can be effectively absorbed by the magnetic device, the resonance phenomenon between the parasitic inductance of the capacitor and the IGBT device can be suppressed, and the damage of the IGBT device can be avoided.
[0035] In one way, the magnetic device includes a magnetic bead.
[0036] The magnetic bead has the function of suppressing high-frequency noise and spike interference on signal lines and power lines. It has the ability to absorb high-frequency signals and can be used to filter high-frequency noise in the circuit, improving the stability and reliability of the circuit. The magnetic bead has a very high resistivity and permeability, and can be equivalent to a series-connected resistor and inductor, and both the resistance value and the inductance value vary with frequency. This characteristic enables the magnetic bead to exhibit different impedance characteristics at different frequencies, thereby achieving the filtering effect. For example, at low frequencies, the magnetic bead can be almost equivalent to a resistor with an extremely small resistance value, while at high frequencies, the impedance characteristic of the magnetic bead shows an increase in inductive reactance, and it can absorb high-frequency noise and interference.
[0037] In one way, as Figure 2 shown, the control circuit further includes a first resistor R1, and the first resistor is connected in parallel between the gate terminal and the emitter terminal of the IGBT device.
[0038] Due to the existence of parasitic capacitance between the gate and the collector and emitter of the IGBT device, the gate potential rises, and current flows through the collector terminal and the emitter terminal. In this case, if the voltage between the collector and the emitter is in a high-voltage state, it may cause the IGBT device to heat up or even be damaged. Here, a first resistor R1 can be connected in parallel between the gate terminal and the emitter terminal of the IGBT device. By sharing part of the voltage through the first resistor, the voltage between the gate terminal and the emitter terminal is released, preventing the voltage between the gate terminal and the emitter terminal of the IGBT device from being too high, and also avoiding the misconnection of the IGBT device due to foreign objects or electromagnetic radiation, etc.
[0039] In one way, the control circuit further includes a second resistor, and the second resistor is connected in parallel with the magnetic device. As Figure 3 shown, the control circuit further includes a second resistor R2, and the second resistor is connected in parallel with the magnetic device. The second resistor can share the current in the control circuit with the magnetic device.
[0040] This embodiment also provides a bridge arm circuit of an IGBT device. The bridge arm circuit includes at least one bridge arm branch; the bridge arm branch is formed by connecting multiple IGBT devices in series; each IGBT device is equipped with the control circuit of the above IGBT device.
[0041] Exemplarily, as Figure 4 shown, the bridge arm circuit of the IGBT device includes two bridge arm branches. Each bridge arm branch includes two IGBT devices. The two IGBT devices in the bridge arm branch are connected in series, and each IGBT device is equipped with the control circuit of the above IGBT device. When performing a bridge arm direct connection test on the bridge arm branch, the magnetic device can effectively absorb the high-frequency noise in the control circuit, suppress the resonance phenomenon between the capacitance and the parasitic inductance of the IGBT device, and avoid the damage of the IGBT device.
[0042] This embodiment also provides a bridge arm direct connection test circuit. The bridge arm direct connection test circuit includes a power supply module and a bus circuit; the power supply module is used to supply power to the bus circuit; the bus circuit includes an energy storage element; the positive terminal and the negative terminal of the bus circuit are respectively connected to both ends of a bridge arm branch in the bridge arm circuit of the IGBT device; the bridge arm circuit of the IGBT device is the bridge arm circuit of the above IGBT device; in this bridge arm branch, the collector terminal and the emitter terminal of the first IGBT device are kept in a connected state; a pulse signal is input to the second IGBT device.
[0043] As Figure 5As shown, the arm direct-conduction test circuit includes a power supply module, a bus circuit, and two IGBT devices. Among them, the power supply module is used to charge the bus circuit. The bus circuit includes energy storage elements such as capacitors. The bus circuit applies a voltage to the arm circuit of the IGBT device. The positive and negative terminals of the bus circuit are respectively connected to both ends of one arm branch in the arm circuit of the IGBT device. Here, a positive driving power supply voltage is applied to the gate terminal of the first IGBT device to keep it always in the conducting state. A single-pulse signal with an adjustable pulse width can be released to the second IGBT device using a signal generator or a control board, and the arm direct-conduction test of the second IGBT device can be performed. Here, an isolation probe can be used to test the voltage between the collector terminal and the emitter terminal of the second IGBT device, a low-voltage probe or an isolation probe can be used to test the gate voltage of the second IGBT device, and a Rogowski coil can be used to test the current flowing through the second IGBT device to obtain the current and voltage waveforms of the arm direct-conduction test of the second IGBT device.
[0044] In this arm direct-conduction test circuit, when the IGBT tube is subjected to the arm direct-conduction test, high-frequency noise in the control circuit can be effectively absorbed through magnetic devices, and the resonance phenomenon between the capacitance and the parasitic inductance of the IGBT device can be suppressed. It can not only solve the glitch interference that occurs during arm direct-conduction, but also ensure the speed of the IGBT device during turn-on and turn-off, and can also significantly improve the waveform of the arm direct-conduction test, making it no longer oscillate.
[0045] In one way, the power supply module in the arm direct-conduction test circuit includes a voltage regulator and a rectifying device.
[0046] The above voltage regulator is used to adjust the voltage in the arm direct-conduction test circuit to meet the test requirements; the above rectifying device is used to convert alternating current into direct current; the above voltage regulator and rectifying device can provide the voltage for activating the energy storage element of the bus circuit.
[0047] In one way, the bus circuit includes a bus capacitor. The positive pole of the bus capacitor is connected to the collector terminal of the first IGBT device; the negative pole of the bus capacitor is connected to the emitter terminal of the second IGBT device.
[0048] That is to say, the bus circuit includes a bus capacitor. The positive pole of the bus capacitor is connected to the collector terminal of the first IGBT device, and this first IGBT device can be called the upper-arm IGBT device; the negative pole of the bus capacitor is connected to the emitter terminal of the second IGBT device, and this second IGBT device can be called the lower-arm IGBT device.
[0049] In one way, the arm direct-conduction test circuit further includes a contactor; the contactor is connected between the power supply module and the bus circuit.
[0050] The bus capacitor voltage can be charged to the required value through a voltage regulator, a rectifier device, and a contactor, which is used to supply electrical energy to the bridge arm circuit of the IGBT device.
[0051] In one way, the bridge arm direct connection test circuit further includes a test module, and the test module includes at least one of an isolation probe, a low-voltage probe, and a Rogowski coil.
[0052] Exemplarily, a bridge arm direct connection test circuit and the bridge arm circuit of the IGBT device are as Figure 6 shown. The bus capacitor voltage is charged to the required value through a voltage regulator, a rectifier device, and a contactor. A positive driving power supply voltage is applied to the gate of the first IGBT device to keep it always in the on state. A single pulse signal with an adjustable pulse width is released to the second IGBT device by a signal generator or a control board, and a direct connection is formed, and the power transistor of the lower bridge arm can be tested for bridge arm direct connection. Here, an isolation probe can be used to test the voltage Vce between the collector terminal and the emitter terminal of the second IGBT device, a low-voltage probe or an isolation probe can be used to test the gate voltage Vge of the second IGBT device, and a Rogowski coil can be used to test the current Ic flowing through the second IGBT device, and the current and voltage waveforms of the bridge arm direct connection test of the second IGBT device can be obtained.
[0053] Figure 7 Shows Figure 6 When there is no magnetic device added to the control circuit of the corresponding IGBT tube, the waveform curve of the voltage Vge between the collector terminal and the emitter terminal of the second IGBT device, the voltage on the blanking capacitor, and the short-circuit current curve. It can be seen that due to the resonance generated by the parasitic inductance and capacitance in the control circuit, the waveforms of Vce and the voltage of the blanking capacitor oscillate severely. In this case, it is easy to cause damage to the gate level GE or CE pole of the IGBT device.
[0054] Figure 8 Shows the use of Figure 6 When the corresponding bridge arm direct connection test circuit is used, the waveform curve of the voltage Vge between the collector terminal and the emitter terminal of the second IGBT device, the voltage on the blanking capacitor, and the short-circuit current curve. It can be seen that the waveforms of Vce and the voltage of the blanking capacitor return to normal. The presence of the magnetic bead effectively suppresses the resonance phenomenon between the capacitance and the parasitic inductance of the IGBT device.
[0055] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the protection circuit of the power device and the circuit system including the power device described above can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0056] In addition, in the description of the embodiments of the present utility model, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0057] If the above-mentioned functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present utility model, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present utility model. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs.
[0058] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0059] Finally, it should be noted that the above embodiments are only specific implementation manners of the present utility model, used to illustrate the technical solutions of the present utility model, rather than limiting it. The protection scope of the present utility model is not limited thereto. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the technical field can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model, and should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.
Claims
1. A control circuit of an IGBT device, characterized in that: The control circuit includes magnetic devices, capacitors, and gate resistors; The first end of the gate resistor is connected to the gate terminal of the IGBT device, and the second end of the gate resistor is connected to the pulse voltage; The first end of the magnetic device is connected to the gate end of the IGBT device, the second end of the magnetic device is connected to the first end of the capacitor, and the second end of the capacitor is connected to the emitter end of the IGBT device.
2. The control circuit according to claim 1, characterized in that: The magnetic device includes magnetic beads.
3. The control circuit according to claim 1, characterized in that: The control circuit also includes a first resistor, which is connected in parallel to the gate terminal and the emitter terminal of the IGBT device.
4. The control circuit according to claim 1, characterized in that: The control circuit also includes a second resistor, which is connected in parallel with the magnetic device.
5. A bridge arm circuit of an IGBT device, characterized in that: The bridge arm circuit includes at least one bridge arm branch; the bridge arm branch is formed by connecting a plurality of IGBT devices in series; Each of the IGBT devices is equipped with the control circuit of the IGBT device according to any one of claims 1 to 4.
6. A bridge arm through-test circuit, characterized in that: The bridge arm direct test circuit comprises a power supply module and a bus circuit; The power supply module is used to supply power to the bus circuit; The positive terminal and the negative terminal of the bus circuit are respectively connected to the two ends of a bridge arm branch in the bridge arm circuit of the IGBT device; the bridge arm circuit of the IGBT device is the bridge arm circuit of the IGBT device according to claim 5; In the bridge arm branch, the collector terminal and the emitter terminal of the first IGBT device remain in a connected state; and the second IGBT device inputs a pulse signal.
7. The bridge arm direct-through test circuit according to claim 6, characterized in that: The power supply module includes a voltage regulator and a rectifier.
8. The bridge arm direct-through test circuit according to claim 6, characterized in that: The bus circuit includes a bus capacitor, a positive electrode of the bus capacitor is connected to the collector terminal of the first IGBT device; and a negative electrode of the bus capacitor is connected to the emitter terminal of the second IGBT device.
9. The bridge arm through-test circuit according to claim 6, characterized in that: The bridge arm direct-through test circuit also includes a contactor; the contactor is connected between the power supply module and the bus circuit.
10. The bridge arm direct-through test circuit according to claim 6, characterized in that: The bridge arm direct-through test circuit also includes a test module, and the test module includes at least one of an isolation probe, a low-voltage probe and a Rogowski coil.