Isolation type DC/DC (direct current/direct current) converter based on modularized multilevel current converter

Abstract

The invention provides an isolation type DC / DC (direct current / direct current) converter based on a modularized multilevel current converter. The converter comprises an input end modular multilevel current converter, a high-frequency transformer and an output end modular multilevel current converter, wherein the input end modular multilevel current converter is connected with the output end modular multilevel current converter through the high-frequency transformer. The input end modular multilevel current converter and the output end modular multilevel current converter respectively adopt MMC (multi media card) sub modules, high voltage is born, the voltage level is high, the transmission capacity is great, the expandability is high, in addition, the alternating current conversion link waveform distortion factor in the middle process is small, the harmonic wave content is low, and the electric isolation can be effectively realized on the input and output side of the converter.

Description

Technical field [0001] The invention belongs to the technical field of power electronics, and specifically relates to an isolated DC / DC converter based on a modular multilevel converter. Background technique [0002] With the application of multi-terminal flexible DC and DC grid technologies based on voltage source converters (VSC), DC / DC converters have become one of the key equipment for constructing DC grids. In the AC system, the AC transformer uses the principle of electromagnetic induction. When the primary coil has an AC transformer schematic flow, AC magnetic flux is generated in the iron core (or magnetic core), causing a voltage (or current) to be induced in the secondary coil. ). In the DC system, the voltage does not change direction, so the voltage conversion of the DC system is far more difficult than the breaking of the AC current. [0003] As one of the key equipment of the DC grid, the main functions of the DC / DC converter should include: ①Realize the connection ...

AI Technical Summary

Problems solved by technology

Among them, resonance technology is widely used in small and medium power DC / DC converters. It has simple structure, convenient control, and high efficiency, but it cannot block the propagation of faults, and it is difficult to debug resonance parameters. At the same time, it is limited by the withstand voltage of thyristors. poor scalability

In the flying capacitor circuit, the voltage ratio between input and output is limited, the voltage level and output ratio are high, or when the capacity is too large, multi-unit cascading is required, which leads to complex control and poor reliability.

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