An isolated high power high transformation ratio modular bidirectional DC converter

Abstract

The invention discloses an isolation type high-power high-transformation-ratio modular bidirectional direct current converter. The isolation type high-power high-transformation-ratio modular bidirectional direct current converter comprises a primary modular multi-level converter, an integrated transformer module and a secondary modular multi-level converter; the integrated transformer module comprises two groups of single-phase three-winding transformers; and the primary side of the integrated transformer module is connected with the output end of the primary modular multi-level converter phase unit while the secondary side is connected with the input end of the secondary modular multi-level converter phase unit. By virtue of the MMC structure adopted by the converter, the voltage level range is enlarged effectively; by virtue of the adopted integrated transformer module, electrical isolation and fault isolation of the primary side and the secondary side are realized, and multi-stage voltage conversion capability is realized; the windings, connected to the upper and lower bridge arms of the MMC phase unit, of the integrated transformers are fully symmetrical, so that the problem ofdirect current magnetization of the conventional transformer can be avoided through a proper modulation strategy, and the transformer size and magnetic core loss can be lowered; and meanwhile, the conventional MMC bridge arm electric reactor and wire inlet / outlet electric reactor can be replaced, so that the number of passive devices can be reduced.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to an isolated high-power high-transformation ratio modular bidirectional DC converter. Background technique [0002] With the substantial improvement of the voltage level and power level of power electronic switching devices, High Voltage Direct Current (HVDC) has developed rapidly at home and abroad. At present, HVDC has been widely used in the fields of connecting asynchronous AC power grids, long-distance high-power transmission, and submarine cable power transmission. [0003] At this stage, due to the continuous development of the cable insulation level, the DC transmission lines constructed in different periods operate at different rated voltages, which makes it impossible to directly operate on the DC side. Therefore, a high-voltage and large-capacity DC / DC converter capable of interconnecting DC lines of different voltage levels will be one of the core equipment for the co...

AI Technical Summary

Problems solved by technology

[0003] At this stage, due to the continuous development of the cable insulation level, the DC transmission lines built in different periods operate at different rated voltages, which makes it impossible to directly network and operate on the DC side

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