With the continuous increase of power grid capacity, transformer damage accidents caused by short-circuit faults are on the rise. Timely and effective measurement of transformer winding deformation can effectively prevent further deterioration of transformer deformation and ensure that transformer does not occur accidents. This paper summarizes the methods, principles, influencing factors and judging criteria of winding deformation detection, and summarizes the important research results in the field of transformer winding deformation in recent years. Finally, this paper compares different detection methods from the aspects of detection methods, influencing factors of test results, detection information, detection sensitivity, deformation judgment methods and detection standards.
A controllable injection diode (CID) is proposed for reducing switching loss and a novel controllable carrier-injection mechanism (CCIM) is investigated in the new device. The CCIM reveals that due to the limit carrier lifetime, the carrier-injection can be controlled in one narrow-pulse time. Based on the CCIM, the CID takes advantage of a PiN diode and a junction field-effect transistor (JFET) for modulating the forward voltage drop. The simulation results show that the forward voltage drop can be modulated to 0.54 V at minimum by the carrier-injection enhancement at 45 A/cm 2 . On the other hand, the JFET weakens carrier-storage effect in the i-layer and the reverse recovery time of the CID is about 0.27 µs at rectifying 50 kHz, which is sufficiently faster than 1.1 µs of the conventional diode. Therefore, the switch loss of the CID can be decreased in a DC-DC buck converter.
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