An IGBT internal state detection method based on short circuit experiment

Abstract

The application discloses an IGBT internal state detection method based on a short circuit experiment and relates to the field of power electronic device health monitoring. In view of the problem that existing detection is time-consuming and laborious and accurate data is difficult to obtain, the application obtains the internal health condition of a device by experiment through external electrical parameters, and the process comprises short circuit experiment design, multi-dimensional signal acquisition, state mapping model establishment and diagnosis implementation. Experiments show that the short circuit current of a multi-chip parallel IGBT is linearly related to the number of effective chips, and the increase of a faulty chip will cause the short circuit current to decrease in steps. The application is non-destructive, high in precision and fast in response, and can provide certain technical support and theoretical reference for preventive maintenance, reliability evaluation and reduction of the unplanned downtime rate of power electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of power electronic device testing technology, specifically to a method for detecting the internal state of an IGBT based on a short-circuit test. Background Technology

[0002] IGBTs (Insulated Gate Bipolar Transistors) are core components of modern power electronic systems, playing a crucial role in power conversion and control. Their reliability directly impacts the safe operation of the entire system. Due to their simple structure, low losses, and fast switching speed, IGBTs have become one of the most commonly used power switching devices in power electronic equipment. During operation, IGBTs frequently face harsh conditions such as high temperature, high voltage, and overcurrent, which can easily damage them. Dynamic experiments on IGBTs under different conditions are conducted to determine the typical characteristics of voltage and current waveforms under different states by comparing the differences between normal and defective states. Research on IGBT internal state detection is of great significance for improving device performance, ensuring system safety, and reducing failure rates. Destructive removal is necessary for detecting the internal health state of IGBTs, as it causes damage to the equipment and is time-consuming and labor-intensive. Therefore, it is necessary to design an experimental scheme to determine the internal health state of IGBTs through external experimental parameters, thus providing a theoretical basis and technical reference for detecting the internal state of IGBTs. Summary of the Invention

[0003] To facilitate accurate assessment of the internal state of IGBTs without compromising the integrity of the IGBT's packaging and internal chip structure, a specific short-circuit experiment is designed to obtain external electrical parameters (such as short-circuit current waveforms and voltage variation characteristics) that effectively reflect the internal health status of the IGBT. Based on these observable external experimental data, this invention proposes a short-circuit experiment-based method for detecting the internal state of IGBTs. This method establishes a mapping relationship between external parameters and internal states, enabling accurate detection of the IGBT's health status and providing crucial technical support for the reliable operation of power electronic equipment.

[0004] The technical solution adopted in this invention is as follows: A method for detecting the internal state of an IGBT based on a short-circuit experiment is proposed, with the following steps: Step 1) Short-circuit experiment design: Design a specific short-circuit pulse sequence, including a preheating stage, a short-circuit triggering stage, and a recovery stage; Step 2) Multi-dimensional signal acquisition: Synchronously acquire signals such as the collector current, gate voltage, and collector-emitter voltage of the IGBT; Step 3) State mapping model: Establish a mapping relationship between characteristic parameters and the internal state of the IGBT (gate aging, collector aging, etc.); Step 4) State detection system: Based on the mapping relationship established in Step 3), detect the health status of the IGBT. Attached Figure Description

[0005] Figure 1: Short-circuit test circuit board Figure 2: IGBT transmission characteristic curve Figure 3: Short-circuit current magnitudes under 15V and 10V drive voltages Figure 4: Pulse sequence diagram of the protected IGBT and the IGBT under test Figure 5: Schematic diagram of short-circuit test Figure 6: Physical image of the experimental platform Figure 7: Magnitude of short-circuit current under different conditions Detailed Implementation The following detailed description, in conjunction with the accompanying drawings, further elaborates on the "IGBT internal state detection method based on short-circuit test" proposed in this invention through a specific example.

[0006] Step 1) Select the IKW08T120 TO packaged IGBT as the test component, and design an experimental circuit board as the mounting component, as shown in the attached diagram. Figure 1 As shown. Set a suitable gate voltage trigger pulse, as indicated by the attached... Figure 2 As shown, the collector current of an IGBT increases with increasing gate voltage. (From the attached diagram...) Figure 3 As shown, under a normal 15V drive voltage and a lower 10V drive voltage, the short-circuit currents are 56A and 12.6A, respectively. (See attached diagram.) Figure 2 and 3 It can be seen that at a lower driving voltage, the collector current of the IGBT is greatly reduced, which makes the experiment safer and more reliable.

[0007] Step 2) Perform a short-circuit test. The following example illustrates this using an IGBT short-circuit test at 450V. First, connect the experimental circuit board to the short-circuit test platform. Second, set the trigger pulses for the protection device and the device under test, ensuring the protection device's trigger pulse completely covers the device under test's trigger pulse. Finally, insert four normal chips into the test base on the experimental circuit board as a control group. Fully charge the bus capacitor to the set voltage value of 450V, activate the trigger pulse, and perform the short-circuit test. Display and save the experimental results using an oscilloscope. Alternatively, bend the collector pins of the chips without inserting them into the test base to simulate a collector fault. Bend 1-3 chips respectively, repeating the above experimental operation to obtain the experimental results.

[0008] Table 1 Short-circuit current values ​​of IGBT under different conditions

[0009] As shown in Table 1, the short-circuit current gradually decreases as the number of IGBT collector faults increases. Under normal conditions, the short-circuit current obtained from the short-circuit test of the control group is 52A. For each additional IGBT chip with a collector fault, the short-circuit current decreases by about 14A, which is statistically significant. Therefore, the short-circuit current of the IGBT under normal conditions can be determined in advance through short-circuit tests. Then, short-circuit tests are performed on the IGBT to be tested to obtain the short-circuit current value. By comparing it with the short-circuit current value obtained under normal conditions, the number of collector faults can be determined.

[0010] Although examples of the present invention have been shown and described above, it is understood that the above examples are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for detecting the internal state of an IGBT based on a short-circuit test, characterized in that, Includes the following steps: 1) Short-circuit triggering stage: Apply a gate drive signal to the IGBT to turn it on, and at the same time control the collector voltage and collector current to reach the preset short-circuit condition; 2) Data acquisition stage: Real-time acquisition of transient waveform data of gate voltage, collector voltage, and collector current of IGBT during short circuit; 3) Feature extraction stage: Extract feature parameters from the acquired transient waveforms, including: gate voltage drop rate, collector current rise time, and short-circuit current peak value; 4) Status identification stage: Input the extracted feature parameters into the preset database to identify the internal status of the IGBT, including: gate bond line health status, collector health status, and emitter health status.

2. The IGBT internal state detection method according to claim 1, characterized in that, In the short-circuit triggering stage, the preset short-circuit conditions are: collector voltage of 450V, short-circuit duration of 10μs, and the sampling frequency used in the data acquisition stage is not less than 100MHz, and the sampling accuracy is not less than 12 bits.

3. The IGBT internal state detection method according to claim 1, characterized in that, It also includes a calibration step: before each probe, a short-circuit test is performed using a standard IGBT sample to establish a baseline feature library.

4. The IGBT internal state detection method according to claim 1, characterized in that, By conducting experimental analysis on a large number of IGBTs with known aging levels, a mapping matrix between external characteristic parameters and specific internal faults was established. This model not only includes qualitative fault classification but also quantitative statistical regularities.

5. The IGBT internal state detection method according to claim 1, characterized in that, The short-circuit triggering stage employs soft-switching technology to reduce electromagnetic interference during the short-circuit process.

6. The IGBT internal state detection method according to claim 1, characterized in that, It also includes a lifespan prediction phase: predicting the remaining lifespan of the IGBT based on historical probe data.

7. An IGBT internal state detection system based on a short-circuit test, characterized in that, include: 1) Short-circuit drive unit: used to generate precisely controlled gate drive signals; 2) Signal acquisition unit: includes a high-speed analog-to-digital converter for acquiring the electrical parameters of the IGBT; 3) Data processing unit: used for feature extraction and state recognition.

8. The IGBT internal state detection system according to claim 7, characterized in that, The short-circuit drive unit is implemented using a programmable logic controller, which supports flexible configuration of multiple short-circuit modes.

Images