High voltage direct current-direct current transformer

Abstract

The invention discloses a high voltage direct current-direct current transformer. The high voltage DC-DC transformer comprises a cascaded modularized current transformer, a duplex-winding medium-low frequency sine-wave transformer and an input parallel-connection modularized current transformer. The cascaded modularized current transformer comprises two bridge arms, and the upper half bridge arm and the lower half bridge arm of the first bridge arm respectively comprise a capacitor bank. The upper half bridge arm and the lower half bridge arm of the second bridge arm respectively comprise two half-bridge topology power modules and one reactor. The duplex-winding medium-low frequency sine-wave transformer comprises a high voltage input winding and a lower voltage output winding, and the two ends of the high voltage input winding are connected with contacts of the two bridge arms respectively. The input parallel-connection modularized current transformer comprises at least one current transformer sub-module of the same structure, wherein the input end of each sub-module is connected with the low voltage output winding, and the output ends of the sub-modules are connected in series or in parallel or in the hybrid mode of series connection and parallel connection. The transformer of the structure has the advantages of being high in transmission capacity, high in efficiency and low in cost and is very significant for accelerating the utilization and marketalization process of the DC-DC transformer.

Description

technical field [0001] The invention relates to a high-voltage DC-DC power conversion and transmission device, in particular to a high-voltage DC-DC transformer. Background technique [0002] High-voltage direct current transmission (HVDC) has the characteristics of large transmission power capacity, low loss, long transmission distance, and good stability, and has broad application prospects. In order to adapt to the direct application of high-voltage direct current transmission to electrical equipment in the future, it is necessary to have a DC transformer device with a function similar to that of an AC isolation transformer to convert high-voltage direct current into isolated low-voltage direct current that meets the requirements of electrical equipment. [0003] Since the withstand voltage of a single power semiconductor device is usually limited, a single power semiconductor device cannot be directly applied to high-voltage applications. In order to realize that low-vo...

AI Technical Summary

Problems solved by technology

However, the power capacity of currently available intermediate frequency or high frequency square wave transformers is difficult to reach hundreds of kilowatts or more, which limits the application of such DC transformers to a certain extent.

[0008] Based on the above analysis, the switching devices on the high-voltage side of the high-voltage DC-DC transformer currently have the problems of withstand voltage and voltage equalization, as well as the problem of insufficient transmission capacity of the existing DC-DC transformer, which needs to be improved

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