Abstract: A high-voltage bushing, comprising a conductive rod and an air cooling device. The conductive rod is internally provided with an air duct, and the air duct comprises an air inlet and an air outlet. The air cooling device comprises at least one fan, and the fan is configured to output airflow so as to blow the airflow into the air duct through the air inlet.

Abstract: Provided in the present disclosure are an IGBT device backside structure and a preparation method therefor, and an IGBT device, the IGBT device backside structure comprising a buffer layer, the buffer layer comprising a first activation efficiency buffer area corresponding to an active area of the IGBT device and a second activation efficiency buffer area corresponding to a terminal area of the IGBT device, the activation efficiency of the first activation efficiency buffer area being less than the activation efficiency of the second activation efficiency buffer area.

Abstract: The present invention provides to a default current testing method of the high voltage direct current converter valve composited by impulse voltage. The technical scheme of the invention composites the symmetrical positive and negative voltage and the impulse into asymmetric positive and negative high voltage, it makes the test valve voltage accurately achieve required peak value at the set time. The test circuit is simple relatively; the high voltage source of the default current test circuit is instead by surge generators. The test method is flexible, safe, and suitable for different DC project converter valves.