An automatic detection circuit and method for leakage current reliability of IGBT devices

Abstract

This invention discloses an automatic leakage current reliability detection circuit and method for IGBT devices. The circuit includes: a PWM control unit; and an interlock detection unit composed of an HTGB test circuit and an HTRB test circuit. The PWM control unit is connected to the interlock detection unit and is used to control the HTGB and HTRB test circuits in the interlock detection unit to automatically perform interlock tests. The interlock detection unit is used to perform HTGB and HTRB interlock tests on the IGBT device to obtain the gate-emitter leakage current or collector-emitter leakage current of the IGBT device. The automatic leakage current reliability detection circuit and method for IGBT devices provided by this invention not only achieves automatic detection of HTGB and HTRB tests, but also protects the device under test when the leakage current is too high, reduces equipment redundancy, simplifies the testing process, and lowers costs.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor technology, and in particular to an automatic leakage current reliability detection circuit and method for IGBT devices. Background Technology

[0002] Currently, Insulated Gate Bipolar Transistor (IGBT) power devices, as voltage-driven devices, are widely used in medium and large power converters in new energy sources and frequency converters. High Temperature Reverse Bias (HTRB) and High Temperature Gate Bias (HTGB) tests are experimental methods for evaluating the reliability of IGBT power devices. According to international standards, HTRB and HTGB tests involve placing the IGBT device under test in a high-temperature chamber and applying a set DC voltage between the gate and emitter or collector and emitter of the IGBT device for 168 hours or 1000 hours.

[0003] Current shortcomings of existing technology:

[0004] (1) Performing HTRB and HTGB tests requires two devices, resulting in redundant test system equipment, increased test procedures, and increased test costs.

[0005] (2) The protection circuit of the test equipment protects the device under test in a single circuit using a fast-blow fuse. When the leakage current of the device under test is very large, the fuse will blow, causing the device under test to burn out. In addition, the fuse blows in milliseconds, which cannot cut off the test circuit in time, making the failure analysis of the device under test more difficult and making it difficult to find the root cause of the device failure. Summary of the Invention

[0006] This invention provides an automatic leakage reliability detection circuit and method for IGBT devices, which solves the defects of system equipment redundancy and lack of protection for IGBT devices in the prior art when detecting leakage reliability of IGBT devices, and realizes automatic detection of leakage reliability of IGBT devices and protection of IGBT devices.

[0007] In a first aspect, the present invention provides an automatic leakage reliability detection circuit for IGBT devices, comprising: a PWM control unit; and an interlock detection unit consisting of an HTGB test circuit and an HTRB test circuit;

[0008] The PWM control unit is connected to the interlock detection unit and is used to control the HTGB test circuit and HTRB test circuit in the interlock detection unit to automatically perform interlock tests.

[0009] The interlock detection unit is used to perform HTGB and HTRB interlock detection on the IGBT device to obtain the gate-emitter leakage current or collector-emitter leakage current of the IGBT device.

[0010] Specifically, the reliability of the IGBT device under test can be verified through HTGB and HTRB tests. The PWM control unit can be any device or circuit capable of generating PWM signals, such as a DSP processor or microcontroller. The HTGB and HTRB test circuits mainly include switching transistors, such as MOSFETs, used in conjunction with the PWM signal to achieve automatic switching between the two tests. During the HTGB test, the gate-emitter leakage current of the IGBT device can be obtained; during the HTRB test, the collector-emitter leakage current of the IGBT device can be obtained. The switching transistors in the HTGB and HTRB test circuits change under the same PWM signal. When the HTGB test is enabled, the HTRB test is stopped; when the HTRB test is enabled, the HTGB test is stopped, thus achieving interlocking between the two tests.

[0011] The above technical solution uses a PWM control unit to control an interlock detection unit composed of an HTGB test circuit and an HTRB test circuit to perform HTGB and HTRB interlock detection on IGBT devices, thereby completing automatic HTGB and HTRB detection in one device, eliminating redundant equipment, shortening the testing process, and reducing testing costs.

[0012] Optionally, the PWM waveform output by the PWM control unit has a preset dead time;

[0013] After the PWM control unit outputs the PWM waveform and the dead time is completed, the HTRB test circuit is started and the HTGB test circuit is stopped; or...

[0014] After the PWM control unit outputs the PWM waveform for a continuous dead time, it starts the HTGB test circuit and stops the HTRB test circuit.

[0015] Specifically, a dead time is preset in the PWM waveform output by the PWM control unit. Dead time is a delay set by the PWM control unit to prevent the switching transistors in HTRB and HTGB tests from simultaneously turning on and burning out the devices due to switching speed issues. In other words, after one switching transistor turns off, there is a delay before the other switching transistor turns on. The dead time is determined by the power rating of the switching transistors.

[0016] The PWM control unit drives the switching transistors in the HTGB and HTRB tests, setting the voltage level to either high or low. This means the voltage level controlling the switching transistors' on / off state can be adjusted as needed. For example, a high output from the PWM control unit enables the HTGB test and disables the HTRB test; a low output also enables the HTGB test and disables the HTRB test. Conversely, a high output enables the HTRB test and disables the HTGB test; a low output also enables the HTRB test and disables the HTGB test.

[0017] Presetting a dead time in the PWM waveform effectively reduces the burn-out phenomenon of the tested device.

[0018] Optionally, it also includes a leakage current acquisition unit;

[0019] The leakage current acquisition unit is connected to the PWM control unit and the interlock detection unit respectively, and is used to obtain the gate-emitter leakage current of the IGBT device from the interlock detection unit and output it to the PWM control unit.

[0020] Specifically, the leakage current acquisition unit can be a current sensor AT, a resistor, or other devices capable of acquiring current. During HTGB testing, it acquires the gate-emitter leakage current of the IGBT device and sends it to the PWM control unit to participate in controlling the HTGB and HTRB tests.

[0021] Optionally, it further includes:

[0022] When the gate-emitter leakage current of the IGBT device is lower than a preset value, the PWM control unit controls the HTGB test circuit and HTRB test circuit in the interlock detection unit to automatically perform interlock tests.

[0023] When the gate-emitter leakage current of the IGBT device is higher than a preset value, the PWM control unit controls the HTGB test circuit in the interlock detection unit to stop working.

[0024] Specifically, the preset value is determined based on the electrical parameters of the IGBT device. When the gate-emitter leakage current of the IGBT device is lower than the preset value, the HTRB test and HTGB test are interlocked in a safe environment; when the gate-emitter leakage current of the IGBT device is higher than the preset value, the HTGB test circuit stops working, promptly shutting off the HTGB test circuit to avoid the burnout of the IGBT device under test due to excessive leakage current, and reducing the difficulty of failure analysis.

[0025] Optionally, the HTGB test circuit includes a MOSFET MOS2, a resistor R2, a resistor R3, and a DC power supply VDC2;

[0026] The gate of the MOS transistor MOS2 is connected in series with the resistor R2 to the PWM control unit; the source of the MOS transistor MOS2 is connected to the gate of the IGBT device; and the drain of the MOS transistor MOS2 is connected in series with the resistor R3 to the DC power supply VDC2.

[0027] Optionally, the HTRB test circuit includes a MOSFET MOS1, a resistor R1, a resistor R4, and a DC power supply VDC1;

[0028] The gate of the MOS transistor MOS1 is connected in series with the resistor R4 to the PWM control unit; the source of the MOS transistor MOS1 is connected to the DC power supply VDC1; and the drain of the MOS transistor MOS1 is connected in series with the resistor R1 to the collector of the IGBT device.

[0029] Optionally, the PWM control unit includes a DSP processor; a leakage current sampling circuit; a leakage current AD circuit; a leakage current DA circuit; and a level conversion circuit.

[0030] The leakage current sampling circuit is connected to the leakage current AD circuit and the leakage current acquisition unit respectively, and is used to convert the acquired gate-emitter leakage current signal of the IGBT device into a voltage signal.

[0031] The DSP processor is connected to the leakage current AD circuit and the leakage current DA circuit respectively, and is used to perform logical calculations on the leakage current of the IGBT device and output control signals to the level conversion circuit.

[0032] The level conversion circuit is connected to the gate of the MOS device in the DA circuit and the interlock detection unit, respectively, and is used to convert the level output by the DA circuit into the level that drives the MOS device in the interlock detection unit.

[0033] In a second aspect, the present invention provides an automatic leakage current reliability detection method for IGBT devices, implemented using the circuit described in the first aspect, comprising:

[0034] Obtain the PWM waveform control signal;

[0035] Based on the PWM waveform control signal, the HTGB test circuit and HTRB test circuit are controlled to perform interlocking tests to obtain the gate-emitter leakage current or collector-emitter leakage current of the IGBT device.

[0036] Optionally, the method further includes:

[0037] Obtain the gate-emitter leakage current of the IGBT device;

[0038] Based on the gate-emitter leakage current of the IGBT device, the HTGB test circuit and the HTRB test circuit are controlled to perform interlocking tests.

[0039] Optionally, based on the gate-emitter leakage current of the IGBT device, the HTGB test circuit and the HTRB test circuit are controlled to perform interlocking tests, further including:

[0040] When the gate-emitter leakage current of the IGBT device is lower than a preset threshold, the HTGB test and HTRB test are switched.

[0041] When the gate-emitter leakage current of the IGBT device exceeds a preset threshold, the HTGB test is stopped.

[0042] Specifically, the PWM waveform control signal is acquired from the PWM control unit. The PWM control unit can use any device that generates the PWM waveform. If the device can have a preset dead time for the PWM waveform, it can better protect the device and prevent it from burning out. The HTGB test circuit and the HTRB test circuit are interlocked. When the HTGB test circuit is activated, the HTRB test circuit is deactivated; conversely, when the HTRB test circuit is activated, the HTGB test circuit is deactivated. The HTGB and HTRB test circuits are tested cyclically under the control of the PWM control unit.

[0043] The gate-emitter leakage current of the IGBT device can be acquired using any current acquisition circuit, such as a current transformer. Based on the acquired gate-emitter leakage current of the IGBT device, the HTGB test circuit and the HTRB test circuit are controlled: when the gate-emitter leakage current of the IGBT device is lower than a preset threshold, the HTGB test and HTRB test are switched; when the gate-emitter leakage current of the IGBT device is higher than the preset threshold, the HTGB test is stopped.

[0044] The above technical solution can enable the IGBT under test to perform HTGB and HTRB tests in the correct environment, and can also shut down the HTGB test in time when the gate leakage current is too large, thereby avoiding device burnout and protecting the IGBT under test.

[0045] The advantages of this invention over the prior art are as follows:

[0046] (1) By controlling the interlock detection unit composed of HTGB test circuit and HTRB test circuit through PWM control unit, the IGBT device is subjected to HTGB and HTRB interlock detection, so that HTGB and HTRB automatic detection can be completed in one device, eliminating redundant equipment, shortening the test process and reducing test cost.

[0047] (2) By collecting the gate-emitter leakage current of the IGBT device through the leakage current acquisition unit, the PWM control unit stops the HTGB test when the gate-emitter leakage current of the IGBT device exceeds the threshold, and shuts off the HTGB test circuit in time to prevent the device from burning out and protect the IGBT device, thereby reducing the difficulty of device failure analysis. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0049] Figure 1 This is one of the schematic diagrams of the automatic leakage reliability detection circuit for the IGBT device of this invention;

[0050] Figure 2 This is the second schematic diagram of the automatic leakage reliability detection circuit for the IGBT device of this invention;

[0051] Figure 3 This is a circuit diagram of the leakage current sampling circuit of the present invention;

[0052] Figure 4 This is the leakage current AD and DA control circuit diagram of the present invention;

[0053] Figure 5 This is a circuit diagram of the level conversion of the present invention;

[0054] Figure 6 This is a flowchart of the leakage current logic judgment of the present invention; Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] The following is combined Figures 1-6 Embodiments of the present invention are described.

[0057] like Figure 1 As shown, this invention provides an automatic leakage reliability detection circuit for IGBT devices, enabling automatic leakage reliability detection of IGBT devices in a low-cost manner. The automatic leakage reliability detection method for IGBT devices provided by this invention employs the following... Figure 1 The circuit shown is implemented as follows. Specifically, the HTGB test circuit consists of NMOS transistor MOS2, resistors R2 and R3, a DC power supply VDC2, and IGBT transistor IGBT1. The gate of MOS2 is connected in series with resistor R2 to the PWM waveform output terminal of the PWM control unit, the source is connected to the gate of IGBT1, and the drain is connected in series with resistor R3 to the DC power supply VDC2.

[0058] The HTRB test circuit consists of an NMOS transistor MOS1, resistors R1 and R4, a DC power supply VDC1, and an IGBT transistor IGBT1. The base of MOS1 is connected in series with resistor R4 to the PWM waveform output terminal of the PWM control unit, the source is connected to VDC1, and the drain is connected in series with resistor R1 to the collector of IGBT1.

[0059] In this embodiment, VDC1 can be above 650V, and VDC2 can be below 100V.

[0060] The PWM control unit controls MOS1 and MOS2 synchronously. It connects an inverter in series with the control signal for the gate of MOS1 to form the control signal for the gate of MOS2. Therefore, when the HTGB test circuit is turned on, the HTRB test circuit is turned off; conversely, when the HTRB test circuit is turned on, the HTGB test circuit is turned off. The two circuits can only work at one time and cannot work at the same time, thus achieving automatic switching between the HTGB and HTRB test circuits.

[0061] The implementation method of this circuit includes the following steps:

[0062] (1) Turn on the power supply, VDC1 and VDC2 are powered on;

[0063] (2) Start the HTRB test circuit;

[0064] (3) Preset the dead time T0 of the PWM control unit. T0 is set according to the power of IGBT1.

[0065] (4) Start the PWM control unit and begin the HTGB test and HTGB test cycle;

[0066] When the PWM control unit outputs a control waveform, the HTRB test circuit and the HTGB test circuit automatically begin interlocking testing:

[0067] When the PWM control unit outputs a high level, after the dead time, MOS2 is in the on state, turning on the HTGB test circuit, and MOS1 is in the off state, turning off the HTRB test circuit. At this time, the gate-emitter leakage current Iges of IGBT1 is obtained through resistor R3.

[0068] When the PWM control unit outputs a low level, after the dead time, MOS1 is in the on state, turning on the HTRB test circuit, and MOS2 is in the off state, turning off the HTGB test circuit. At this time, the collector-emitter leakage current Ices of IGBT1 is obtained through resistor R1.

[0069] When the waveform output by the PWM control unit changes from high to low, the HTGB test circuit and the HTRB test circuit automatically perform interlock detection.

[0070] Those skilled in the art should know that a high-level output from the PWM control unit can also be used to control MOS1 to turn on and MOS2 to turn off. In other words, the level at which the MOS transistor is turned on or off can be adjusted as needed.

[0071] In one implementation, the circuit is further provided with a leakage current acquisition unit for acquiring the gate-emitter leakage current of the IGBT device. Since the output of the leakage current acquisition unit is connected to the PWM control unit and participates in the generation of the PWM waveform, the PWM control unit will change accordingly.

[0072] This example, which uses a leakage current acquisition unit as a current sensor, is provided for illustration only and is not intended to limit the scope of protection of this invention.

[0073] like Figure 2 As shown, the leakage current acquisition unit is a current sensor AT1. One end of the sensor is connected to the DC power supply VDC2 via a series resistor R3, the other end is connected to the collector of MOS2, and the third end is connected to the PWM control unit to control the output of the PWM waveform.

[0074] The implementation method of this circuit includes the following steps:

[0075] (1) Turn on the power supply, VDC1 and VDC2 are powered on;

[0076] (2) Start the HTRB test circuit;

[0077] (3) Preset the dead time T0 of the PWM control unit;

[0078] (4) Start the PWM control unit and begin the HTGB test and HTGB test cycle;

[0079] When the PWM control unit outputs a control waveform, the HTRB test circuit and the HTGB test circuit automatically begin interlocking testing:

[0080] a. When the gate-emitter leakage current of IGBT1 collected by AT1 is lower than the preset value, the HTGB test circuit and HTRB test circuit can safely perform the following interlock tests:

[0081] When the PWM control unit outputs a high level, after the dead time, MOS2 is in the on state, turning on the HTGB test circuit, while MOS1 is in the off state, turning off the HTRB test circuit. At this time, the gate-emitter current Iges of IGBT1 is obtained through resistor R3.

[0082] When the PWM control unit outputs a low level, after the dead time, MOS1 is in the on state, turning on the HTRB test circuit, and MOS2 is in the off state, turning off the HTGB test circuit. At this time, the collector-emitter current Ices of IGBT1 is obtained through resistor R1.

[0083] b. When the gate-emitter leakage current of IGBT1 collected by AT1 is higher than the preset value, the PWM control unit outputs a low level to turn off the HTGB test.

[0084] Those skilled in the art should know that a high-level output from the PWM control unit can also be used to control MOS1 to turn on and MOS2 to turn off. In other words, the level at which the MOS transistor is turned on or off can be adjusted as needed.

[0085] In one implementation, the PWM control unit includes a DSP processor; a leakage current sampling circuit; a leakage current AD circuit; a leakage current DA circuit; a level conversion circuit; and so on. Figure 3 As shown, this circuit is used to convert the acquired gate-emitter leakage current signal of the IGBT device into a voltage signal and input it to the leakage current AD chip. Figure 4 As shown, the leakage current AD circuit is used to convert analog signals into digital signals for transmission to the DSP digital signal processor. The DSP processor processes the leakage current and outputs it to the leakage current DA circuit, which converts the digital signal back into an analog signal and connects it to the level conversion circuit. Figure 5As shown, the level shifting circuit is used to convert a low voltage to a high voltage, thereby driving the gate of the MOSFET. After receiving the signal from the leakage current AD output, the DSP processor performs the following... Figure 6 The steps shown mainly involve making logical judgments based on the magnitude of the leakage current to control the output of the PWM control unit.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic leakage current reliability detection circuit for an IGBT device, characterized in that, include: PWM control unit; interlock detection unit consisting of HTGB test circuit and HTRB test circuit; The PWM control unit is connected to the interlock detection unit and is used to control the HTGB test circuit and HTRB test circuit in the interlock detection unit to automatically perform interlock tests. The interlock detection unit is used to perform HTGB and HTRB interlock detection on the IGBT device to obtain the gate-emitter leakage current or collector-emitter leakage current of the IGBT device. It also includes a leakage current acquisition unit; The leakage current acquisition unit is connected to the PWM control unit and the interlock detection unit respectively, and is used to acquire the gate-emitter leakage current of the IGBT device from the interlock detection unit and output it to the PWM control unit; When the gate-emitter leakage current of the IGBT device is lower than a preset value, the PWM control unit controls the HTGB test circuit and HTRB test circuit in the interlock detection unit to automatically perform interlock tests. When the gate-emitter leakage current of the IGBT device is higher than a preset value, the PWM control unit controls the HTGB test circuit in the interlock detection unit to stop working.

2. The automatic leakage current reliability detection circuit for IGBT devices according to claim 1, characterized in that, The PWM waveform output by the PWM control unit has a preset dead time. After the PWM control unit outputs the PWM waveform and the dead time is completed, the HTRB test circuit is started and the HTGB test circuit is stopped; or... After the PWM control unit outputs the PWM waveform for a continuous dead time, it starts the HTGB test circuit and stops the HTRB test circuit.

3. The automatic leakage current reliability detection circuit for IGBT devices according to claim 1, characterized in that, The HTGB test circuit includes MOSFET MOS2, resistor R2, resistor R3, and DC power supply VDC2. The gate of the MOS transistor MOS2 is connected in series with the resistor R2 to the PWM control unit; the source of the MOS transistor MOS2 is connected to the gate of the IGBT device; and the drain of the MOS transistor MOS2 is connected in series with the resistor R3 to the DC power supply VDC2.

4. The automatic leakage current reliability detection circuit for IGBT devices according to claim 1, characterized in that, The HTRB test circuit includes a MOSFET MOS1, a resistor R1, a resistor R4, and a DC power supply VDC1. The gate of the MOS transistor MOS1 is connected in series with the resistor R4 to the PWM control unit; the source of the MOS transistor MOS1 is connected to the DC power supply VDC1; and the drain of the MOS transistor MOS1 is connected in series with the resistor R1 to the collector of the IGBT device.

5. The automatic leakage current reliability detection circuit for IGBT devices according to claim 1, characterized in that, The PWM control unit includes a DSP processor; a leakage current sampling circuit; a leakage current AD circuit; a leakage current DA circuit; and a level conversion circuit. The leakage current sampling circuit is connected to the leakage current AD circuit and the leakage current acquisition unit respectively, and is used to convert the acquired gate-emitter leakage current signal of the IGBT device into a voltage signal. The DSP processor is connected to the leakage current AD circuit and the leakage current DA circuit respectively, and is used to perform logical calculations on the leakage current of the IGBT device and output control signals to the level conversion circuit. The level conversion circuit is connected to the gate of the MOS device in the DA circuit and the interlock detection unit, respectively, and is used to convert the level output by the DA circuit into the level that drives the MOS device in the interlock detection unit.

6. An automatic method for detecting leakage current reliability of IGBT devices, implemented using the circuit described in any one of claims 1-5, characterized in that, The method includes: Obtain the PWM waveform control signal; Based on the PWM waveform control signal, the HTGB test circuit and HTRB test circuit are controlled to perform interlocking tests to obtain the gate-emitter leakage current or collector-emitter leakage current of the IGBT device.

7. The automatic leakage current reliability detection method for IGBT devices according to claim 6, characterized in that, The method further includes: Obtain the gate-emitter leakage current of the IGBT device; Based on the gate-emitter leakage current of the IGBT device, the HTGB test circuit and the HTRB test circuit are controlled to perform interlocking tests.

8. The automatic leakage current reliability detection method for IGBT devices according to claim 7, characterized in that, Based on the gate-emitter leakage current of IGBT devices, the HTGB and HTRB test circuits are controlled for interlocking testing, further including: When the gate-emitter leakage current of the IGBT device is lower than a preset threshold, the HTGB test and HTRB test are switched. When the gate-emitter leakage current of the IGBT device exceeds a preset threshold, the HTGB test is stopped.

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