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Empirical mode decomposition (EMD) is a signal processing method used to extract intrinsic mode functions (IMFs) from a complicated signal. For a measurement with two or more correlated inputs, finding and capturing the correlated IMFs is a critical challenge that must be confronted. In this paper, a new correlated EMD method is proposed. The cross-correlation method was employed to determine dependence between the IMFs. To verify feasibility, an analysis was performed on simulated test signals and practically measured partial discharge (PD) signals collected from several acoustic emission sensors. At the surface of the gas-insulated transmission line, the PD signal arrived at the AE sensors with varying time delays and unique mechanism vibrations. Following an abnormal detection using the standard-deviation variation, the PD signal and the background signal of each sensor were applied using the correlated-EMD method. A twice correlated-EMD calculation was applied to the signals for the purpose of noise elimination. In addition, the unwanted low-frequency IMFs induced from the EMD calculations were excluded. The experimental results reveal that the correlated-EMD method performs well on both selecting and denoising the correlated IMFs. The results further provide analysis on correlated-input applications with a precise signal completely induced from the disturbance.

Abstract:In this study, a novel high step-up DC-DC converter was successfully integrated using coupled inductor and switched capacitor techniques. High step-up DC-DC gain was achieved using a coupled inductor when capacitors charged and discharged energy, respectively. In addition, energy was recovered from the leakage inductance of the coupled inductor by using a passive clamp circuit. Therefore, the voltage stress of the main power switch was almost reduced to 1/7 V o (output voltage). Moreover, the coupled inductor alleviated the reverse-recovery problem of the diode. The proposed circuit efficiency can be further improved and high voltage gain can be achieved. The operation principle and steady-state analysis of the proposed converter were discussed. Finally, a hardware prototype circuit with input voltage of 24 V, output voltage of up to 400 V, and maximum power of 150 W was constructed in a laboratory; the maximum efficiency was almost 96.2%.

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