Two level conversion type AC-DC Power electronic transformer

Abstract

The invention discloses a two level conversion type AC-DC Power electronic transformer which includes three filter inductors Lga, Lgb and Lgc, three cascade converters CCA, CCB and CCC, three low frequency blocking capacitors CLFB1, CLFB2 and CLFB3, three high frequency isolation transformers THF1, THF2 and THF3, and three high frequency rectifiers REC1, REC2 and REC3. The two level conversion type AC-DC Power electronic transformer includes two level transformation involving a direct AC / AC conversion from lower frequency AC to high frequency AC and an AC / DC conversion from high frequency AC to DC. The cascade converters CCA, CCB and CCC realize direct AC / AC conversion of power which changes from lower frequency AC to high frequency AC, and the high frequency rectifiers REC1, REC2 and REC3 realize high frequency AC / DC conversion of power. Compared with existed topology of power electronic transformers, according to the invention, the two level conversion type AC-DC Power electronic transformer herein has less transformation levels, has less switch devices and high operation efficiency.

Description

technical field [0001] The invention relates to a power electronic transformer, in particular to a two-stage high-voltage AC input-DC output power electronic transformer. Background technique [0002] As a new type of electrical equipment in modern smart grids, power electronic transformers generally realize various functions such as electrical isolation, voltage conversion, and power transmission through power electronic converters + high-frequency isolation transformers. Power electronic transformers require less core material than conventional power frequency transformers due to the electrical isolation achieved by high-frequency transformers ranging from hundreds of Hz to tens of kHz. In addition, because the power electronic transformer can provide a DC interface, it has the ability to directly access renewable energy such as photovoltaics, and at the same time can compensate the reactive power and harmonics of the AC grid, isolate the primary and secondary side faults,...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome the disadvantages of the existing power electronic transformer circuit topology from input to output through many stages of electric energy conversion, low efficiency, large number of semiconductor switching devices, poor reliability, etc., and propose a two-stage conversion type AC- DC power electronic transformer and its control method

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