Abstract: A lossless exciting current sampling circuit for an isolated converter includes first and second voltage sampling circuits and a subtraction circuit formed by an operational amplifier. The two sampling circuits sample voltages of the primary winding of an isolation transformer, with outputs fed into the subtracter. The subtracter output is the circuit's output. RC low-pass filters with large time constants are used as primary voltage sampling circuits, realizing integration of voltage differences between the exciting inductance terminals, enabling lossless current sampling without resistors or transformers. The current sampling result is utilized for volt-second balance control, realized along with a hold circuit and comparator which compares the sampling hold result with the current sampling result to generate a control signal.

Abstract: An anti-cavitation damping composite metal structure for a flow passage component and a preparation method thereof are provided. The preparation method includes: cladding a gradient functional material layer by layer on a substrate of a flow passage component; forming periodic structures on a surface of each layer of the gradient functional material through etching by an ultrafast laser to absorb a part of an impact load energy caused by cavitation of the flow passage component, where the layers of the gradient functional material form a gradient coating with a toughness increasing layer by layer and a hardness decreasing layer by layer from bottom to top; and forming nano twins on a surface layer by a laser shock peening technique, and implanting a residual compressive stress to further improve anti-cavitation resistance of a surface.