Jie Zhang

Effective condition monitoring (CM) technology ensures the safe operation of insulated gate bipolar transistors (IGBTs). Most CM methods for IGBTs focus on extracting electrical, thermal, and magnetic parameters. Recent studies indicate that at the switching moment, IGBTs can emit the switching stress wave (SSW) that is detectable by the acoustic emission (AE) sensors. However, using these SSWs to monitor the health status of IGBTs, even for discrete devices with relatively simple package structures, remains challenging. This paper investigates how SSWs from discrete IGBTs during power cycling change as bonding wires degrade and whether these waves are promising for monitoring the condition of internal bonding wires. In this work, a power cycle test platform and an SSW test platform for discrete IGBTs are built, and SSWs from discrete IGBTs during power cycling are analyzed. Results show that SSWs vary with the degradation of the device’s bonding wires, with changes in the time domain indicator of signal energy, reflecting SSW strength, and the frequency domain indicator of the center of gravity frequency, reflecting frequency shifts. These findings suggest the possibility for developing acoustic emission-based detection technology (AEDT) in CM of the IGBT.

Due to the effects of electromagnetic stress and thermoelastic effect, mechanical stress waves are generated in power semiconductor devices during turn-off moment. The characteristics of these turn-off stress waves vary when power semiconductor devices are subjected to different temperature environments. Measuring these turn-off stress waves is beneficial for analyzing the influence of temperature on the physical properties of power semiconductor devices. As a traditional contact-based mechanical stress wave detection method, acoustic emission testing (AET) is inevitably influenced by temperature, affecting the sensor’s measurement performance. This study employs non-contact laser Doppler vibrometry (LDV) to measure turn-off stress waves in silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) at different temperatures. By comparing the signals measured using AET, it has been demonstrated that the signals measured using LDV more effectively reflect the temperature-dependent variations in turn-off stress waves of SiC MOSFET. This research not only broadens the application scope of condition monitoring technology based on mechanical stress wave parameters for power semiconductor devices but also demonstrates the unique advantages of LDV in condition monitoring of power semiconductor devices in different temperature environments.

Power semiconductor device condition monitoring technology based on the mechanical stress wave (MSW) is an important means to study device failure mechanisms and evaluate device reliability. However, MSW signals have mainly been detected through acoustic emission sensors for contact detection. The operating temperature of the device will affect the detection results, and the presence of MSW low-frequency components may be overlooked due to limitations in sensor performance. This paper proposes an offline, non-contact MSW measurement method based on laser Doppler vibrometer for power semiconductor devices. This method obtained the complete MSW signal generated during the switching process of power semiconductor devices, especially the low-frequency components below 20 kHz. Moreover, the proposed method exhibits greater sensitivity in detecting the high-frequency components of the MSW compared to the contact detection. This study extends the detection methods and frequency ranges for the MSW in power semiconductor devices, thereby expecting to facilitate the generation and propagation mechanisms research of the MSW.