Zero-sequence component suppression system and suppression method for three-phase H bridge

Abstract

The invention provides a zero-sequence component suppression system and suppression method for a three-phase H bridge. The system comprises a DC bus support module, wherein the DC bus support module is located at an input end of the system and provides a bus support voltage to a DC side; an output end of the DC bus support module is connected with a three-phase H bridge DC / AC conversion module for converting a DC input an AC; the output end of the three-phase H bridge DC / AC conversion module is connected with a three-phase filter module for filtering AC output of a converter; the output end of the three-phase filter module is connected with a transformer module; and the transformer module boosts a voltage output by the converter and is connected to a power grid. In a 'virtual angle connection' three-phase H bridge PWM modulation manner, 'delta' connection is formed by six bridge arms of the three-phase H bridge through control on switch tubes in various bridge arms in the three-phase H bridge, namely one modulated wave is shared by an X phase and a B phase, one modulated wave is shared by a Y phase and a C phase and one modulated wave is shared by a Z phase and an A phase. Due to the connection method, a zero-sequence current forms a loop current and cannot flow outside, so that the zero-sequence component is effectively suppressed.

Description

technical field [0001] The invention relates to the technical field of three-phase H-bridge zero-sequence component suppression, in particular to a three-phase H-bridge zero-sequence component suppression system and suppression method. Background technique [0002] Three-phase H-bridge topology such as Figure 1a and Figure 1b As shown, the topology is a three-phase converter composed of three single-phase H-bridges, which has high output power density and is easy to realize multi-level modulation, so this topology is commonly used in multi-level converters. Since there is no power coupling between the three-phase output currents of this topology, the two bridge arms of each phase H-bridge form a current loop with each other, so the rear stage of the topology converter needs a three-phase six-tap transformer to be connected to it. Currently, there are two types of transformers used in the prior art: [0003] 1. The transformer adopts a three-phase transformer group compos...

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Problems solved by technology

[0006] In order to overcome the problem of poor separation effect in the above-mentioned prior art, the object of the present invention is to provide a three-phase H-bridge zero-sequence component suppression system and suppression method, which effectively suppresses the PWM zero-sequence component of the three-phase H-bridge without Easy to implement with hardware changes; significantly reduces transformer cost

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