Input-series-output-parallel automatic voltage equalizing DC transformer based on full-bridge topological structure

Abstract

The invention provides an input-series-output-parallel auto balanced voltage transformer based on a full-bridge topology belonging to the dc transformer field. The dc transformer is composed of N dc transformers with a full-bridge topology structure (N is natural number), wherein the input ends of the dc transformer power modules are mutual in-series and connected to the positive and negative terminals of a dc voltage source, the output ends are mutual parallel and connected to two ends of an output filter capacitor. Each power module of the full-bridge topology structure dc transformer comprises an input capacitance, a full-bridge circuit, a series inductance, a high frequency isolating transformer and an output rectifier circuit. The full-bridge circuit comprises a full-bridge circuit formed by four switch tubes, each power module works in the same work frequency or a different work frequency at a duty cycle near to 0.5. The balance voltage at each input side of the power module is auto realized using the input-series-output-parallel structure and secondary side clamping action of the transformer. The transformer provided by the invention not only can be applied in the occasion that no voltage adjustment is needed during the input and output high voltage, but also the occasion of different input voltage grades, which has a good application flexibility and has certain application prospects in the high voltage input and high power occasions.

Description

Technical field: [0001] The invention relates to an isolated direct current transformer applied to high voltage input and low voltage output, which belongs to the direct current isolation step-down technology in electric energy conversion devices. Background technique: [0002] Compared with AC transmission, HVDC transmission has the characteristics of large transmission power capacity, small loss, long transmission distance, good stability, etc., and has broad application prospects. At present, in the rectification side and inverter side of the HVDC power transmission system, power frequency transformers are still required to connect to the AC power grid, which is large in size and heavy in weight. DC transmission is still used as an auxiliary function of AC transmission and is not directly used for electrical equipment. In order to adapt to the direct application of high-voltage direct current transmission to electrical equipment in the future, especially for independent ...

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Problems solved by technology

In order to adapt to the direct application of HVDC power transmission to electrical equipment in the future, especially for independent power systems such as large-scale non-grid-connected wind power generation, the original solution is cumbersome and uneconomical

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