An improved three-phase four-leg topology for active power decoupling

Abstract

The invention belongs to the technical field of power electronics, and specifically relates to an improved three-phase four-bridge arm topology for realizing active power decoupling used in a system containing a single / three-phase unbalanced load or source. The improved three-phase four-bridge arm topology comprises eight switch tubes S1, S2, S3, S4, S5, S6, S7, S8, four inductors La, Lb, Lc and Ln and five capacitors Ca, Cb, Cc, Cn, Cdc. When the single / three-phase unbalanced load or source exists, a fourth bridge arm is controlled, a passage is provided for a zero-sequence component by usinga center line, and then three-phase phase voltage balance is realized, and high-quality power supply is provided for the load; secondary impulse power on an alternating current side is provided by the capacitors on the alternating current side through active power decoupling control, a direct current side just needs to provide the average power component on the alternating current side, on the basis of without adding switch devices, a secondary impulse power decoupling purpose is realized, the tolerance of supporting capacitors on the direct current side can be reduced effectively, and the influence of secondary impulse power on direct current source or front system control performance is avoided.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to an improved three-phase four-bridge arm topology for realizing active power decoupling, which is used in a system with single / three-phase unbalanced loads or sources. Background technique [0002] With the large-scale application of distributed energy, the research of microgrid has attracted more and more attention. Its operation is flexible and reliable, and it can be connected to the grid or operate autonomously in isolated islands in the event of grid failure. The best way to get energy. In the prior art, when the microgrid works in the island mode, the existence of single / three-phase unbalanced loads or sources easily causes unbalanced three-phase voltages. The three-phase three-leg converter with Δ / Yn transformer uses the transformer to provide the zero-sequence path. This method is simple to control, but due to the addition of the power frequency tran...

AI Technical Summary

Problems solved by technology

In order to achieve power decoupling on the AC and DC sides, the traditional three-phase four-bridge arm usually adopts passive power decoupling schemes such as increasing the capacitance on the DC side, which leads to a further increase in cost and volume, affects the life of the system, and is not conducive to the use of three-phase Advantages of the four-leg topology

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