Novel AC power electronic transformer topological structure

Abstract

The invention proposes a novel AC power electronic transformer topological structure. According to different application occasions, the AC power electronic transformer topological structure proposed by the invention can be divided to two types and comprises a novel power electronic traction transformer topological structure applied to a high-speed train traction transmission system and a novel three-phase AC power electronic transformer topological structure applied to an interconnection three-phase middle / high-voltage AC power grid and a low-voltage DC power grid. With the basic topological structure proposed by the invention, an arbitrary fault converter in a DC / DC conversion unit can be automatically removed, and a DC bypass contactor is not needed to be employed; and on the basis of abasic topological structure, a bidirectional isolation DC / DC converter can be arbitrarily reduced while the bidirectional isolation DC / DC converter in at least one group of DC / DC conversion unit is maintained by sharing half-bridge arm of a voltage sharing converter and a cascaded isolation DC / DC converter, so that the numbers of middle / high-frequency transformers and low-voltage switch devices can be reduced, and the volume, the weight and the cost of the AC power electronic transformer are further reduced.

Description

technical field [0001] The invention relates to a novel topological structure of an AC power electronic transformer, which is suitable for interconnecting a medium / high voltage AC power grid and a low voltage DC power grid, and is also suitable for a traction drive system of a high-speed EMU. Background technique [0002] Power electronic transformer is a kind of power conversion device with high-frequency link, which can realize voltage conversion and electrical isolation. It has broad application prospects in traction drive system of EMU and AC-DC interconnection power system. According to the input and output voltage standards of power electronic transformers, they can be roughly divided into two categories: 1. DC power electronic transformers, whose input and output voltages are both DC; 2. AC power electronic transformers, whose input voltage is AC and output The voltage is DC. [0003] DC power electronic transformers can be used in auxiliary power supply systems for ...

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Problems solved by technology

However, this circuit structure has the following problems: 1. The number of medium / high-frequency transformers and low-voltage switching devices is large; 2. Since each medium / high-frequency transformer needs to be designed according to the same high-voltage insulation level, the high-voltage Insulation limits the further reduction of the volume of the medium / high frequency transformer. In this case, the number of medium / high frequency transformers is large, which is not conducive to the further reduction of the overall volume of the power electronic traction transformer; 3. The DC / DC conversion unit consists of Multiple DC / DC converters are input in series and outputs are connected in series. When any DC / DC converter fails, the faulty converter is difficult to be effectively isolated, and the reliability of the DC / DC conversion unit is not high.

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