High-voltage back-to-back converter

Abstract

The invention relates to a high-voltage back-to-back converter. The converter comprises a plurality of bridge arms with the same structure, wherein the upper bridge arm and lower bridge arm of each bridge arm both contain the same number of low-voltage power units; each bridge arm corresponds to single input or output phase of the back-to-back converter; the upper ends of the bridge arms are connected, the lower ends of the bridge arms are connected, the high-voltage DC bus does not need to support capacitors; each bridge arm comprises an induction module which is composed of two capacitors in serial connection; the connection point of two terminals of the two capacitors is used as the output terminal of the bridge arm; and one of the residual two terminals of the two capacitors is connected with the lower end of the upper bridge arm of the bridge arm, and the other terminal is connected with the upper end of the lower bridge arm of the bridge arm. The invention is applicable to the high-voltage AC drive occasions such as single phase / single phase, single phase / three phase, three phase / three phase and three phase / multiphase.

Description

technical field [0001] The invention relates to a multi-level back-to-back converter, in particular to a multi-level back-to-back converter capable of realizing energy bidirectional flow and control in a high-voltage AC transmission system. Background technique [0002] With the development of power electronics and AC drive technology, high-voltage AC drive systems, such as high-voltage frequency conversion speed control systems, as one of the main means of energy saving and emission reduction, have been more and more widely used in various fields of the national economy. In the practical application of high-voltage AC drive system, in many occasions, the energy of the motor needs to be fed back to the grid side when braking, so as to save energy. Therefore, the back-to-back converter with energy bidirectional flow and control capabilities has also been widely used. . [0003] However, at the current level of power electronics technology development, a single and single pow...

AI Technical Summary

Problems solved by technology

However, the high-voltage DC bus of these types of converters generally requires high-voltage DC capacitors. As the number of levels increases, the number of diodes or high-voltage capacitors will also increase sharply, and there is a problem of capacitor voltage equalization. Therefore, in practical applications, the three-electric The flat structure is the most widely used. However, it is almost impossible for a three-level converter to withstand a high voltage above 7kV at the current level of power electronic switching devices.

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