An isolated dual full-bridge active neutral point clamped three-level dc/dc converter

Abstract

The invention discloses an isolated double full-bridge ANPC three-level DC / DC converter, comprising: two full-bridge ANPCs, a transformer and an inductor; each full-bridge ANPC is composed of two voltage-dividing capacitors and two half-bridge ANPCs; The divider capacitor is connected in series with V dc , the voltage across each divider capacitor is V dc / 2, the half-bridge ANPC connects the midpoint of the bridge arm of the series switching tube to the series midpoint of the two DC voltage dividing capacitors, so that the voltage stress on the switching tube in each half-bridge ANPC is V dc / 2; each half-bridge ANPC can output V dc / 2, 0, and -V dc / 2 three levels, the output level of each full-bridge ANPC is determined by the difference between the output levels of the two half-bridge ANPCs, and can output V dc , V dc / 2, 0, -V dc / 2 and -V dc Five levels, two full-bridge ANPC active bridges can output five levels so that the voltage at both ends of the inductor has nine levels. The invention increases the number of alternating voltage series and obtains a higher degree of control freedom.

Description

technical field [0001] The present invention relates to the field of DC / DC converters, in particular to an isolated double full-bridge active neutral point clamping type (Active Neutral Point Clamped, ANPC) three-level DC / DC converter. Background technique [0002] A DC / DC converter with galvanic isolation and bidirectional power transmission capability can realize power transmission and voltage transformation between grids of different voltage levels. Dual Active Bridge (DAB) DC / DC converter has the advantages of electrical isolation, high power density, bidirectional flow of energy, and easy realization of soft switching. It has been used in the fields of renewable energy and DC power transmission and distribution. It has been extensively researched and applied. [0003] A common DAB topology is a dual H-bridge DAB, where the voltage stress on the switching devices is the DC bus voltage. Since the withstand voltage level of the full-control power device is much lower tha...

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Problems solved by technology

[0009] Aiming at the defects of the prior art, the purpose of the present invention is to solve the problem of high voltage level of the prior art switching tube, low switching frequency, difficulty in transformer design, low efficiency, and less freedom of control in power control and DC bus capacitors under high voltage levels. The technical problem that it is difficult to achieve high-precision and fast adjustment control under the condition of mutual coupling of various indicators such as point voltage balance and soft switching control

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