ak is the coefficient, which can be determined by tests, so we can know the life state according to Equation (6).3.?Experiments and Feature Data ExtractionThe performance of the presented monitoring of MOSFET degradation was verified by physical experiments. The test system is shown in Figure 3, and includes: (1) the SMPS, whose MOSFET is considered pluggable, making it easy to replace a MOSFET with another of the same type but with varying degrees of degradation; (2) Temperature control chamber. MOSFETs undergo accelerated degradation using thermal overstress; (3) High precision voltage sensor, where the input and output signals are transformed to send to the data acquisition card; (4) High speed, high precision data acquisition card, collecting excitation signals and output signals on a PC.
Figure 3.Experimental setup.The data acquisition and processing is shown in Figure 4. First, we obtain the excitation signal and output signal suing high precision voltage sensors. Then the signals are acquired by a NI acquisition card and sent to the PC. A program is developed to deal with data based on the Labview software. The program flow chart is shown in Figure 5.Figure 4.Diagram of the data acquisition process.Figure 5.Program flow chart of degradation state judgment and prediction for MOSFET.In order to verify the method, we use ten MOSFETs, which have different degrees of degradation. Here, we take advantage of the temperature change to obtain the MOSFETs with different degradation. The MOSFETs are put into the circuit, respectively.
First, we denoise the transient response to a square control signal at the gate, and then use FIR method to filter the signals. Based on the Volterra series transform, we extract the feature signals of the degradat
Many researchers have investigated the use of a fiber Bragg grating (FBG) as an effective ultrasonic sensor due to this grating’s inherent advantages, including its flexibility, immunity to electromagnetic interference, corrosion resistance, small size, and ability to be embedded into various materials. In these areas, an FBG outperforms the traditional lead-zirconate-titanate (PZT) sensor. The applications of ultrasonic detection by FBG have two main features. Some researchers use the FBG as a hydrophone, which involves immersing the FBG in water or another liquid [1].
In this case, the ultrasonic frequency is typically high, and the fiber is under isotropic stress. Alternately, other researchers use FBGs in the field of non-destructive testing (NDT) or structural health Drug_discovery monitoring (SHM), where the FBG is normally attached to material surfaces or embedded into materials [2,3]. In these cases, the utilized frequency range is normally under 2 MHz, and stress is always exerted in a dominant direction. While, in the first case Rosenthal et al.