Feasibility Study of Mechanical Stress Wave Detection in Power Semiconductor Devices Using Bare FBG Sensors

Power semiconductor devices generate mechanical stress wave (MSW) signals during switching processes, which can be used for condition monitoring (CM) of these devices with the advantages of noninvasive and non-destructive monitoring. Existing MSW signal detection methods are susceptible to electromagnetic interference and environmental factors (such as high temperature, high voltage, confined spaces, or structural constraints), which limit their adaptability in complex working conditions. Bare fiber Bragg grating (FBG) sensors offer strong resistance to electromagnetic interference and excellent environmental adaptability. Therefore, this paper proposes a transient high-frequency MSW measurement method for power semiconductor devices based on high-sample-rate bare FBG sensors. The MSW signals generated during the switching process of power semiconductor devices are successfully captured based on high-sample-rate bare FBG sensors for the first time. Comparative signal measurements between single-ended acoustic emission (AE) sensors and bare FBG sensors demonstrate the electromagnetic interference resistance capability of bare FBG sensors. Moreover, this study expands the application range of MSW detection methods for power semiconductor devices and provides new technical support for investigating the generation and propagation mechanisms of MSW signals.