Combined input-series output-parallel direct current transformer suitable for medium voltage direct current power distribution network and control method thereof

Abstract

The invention discloses a combined input-series output-parallel direct current transformer suitable for a medium voltage direct current power distribution network and a control method thereof. The direct current transformer includes N input-series output-parallel direct current-direct current converter modules, wherein the N is an integer greater then or equal to 2. The N input-series output-parallel direct current-direct current converter modules include one DAB converter module and N-1 LC series resonant converter modules. The LC series resonant converter modules are used as main power transmission modules of the whole converter, and the DAB converter module is taken as a secondary power transmission module and output power control module. The input terminals of the DAB converter moduleand the LC series resonant converter modules are connected in series to a medium voltage direct current terminal, and the output terminals are connected in parallel to a low voltage direct current terminal. Each converter module has an independent control loop and no interconnection wire is arranged among the converter modules so as to realize the independent control of the modules. The combined input-series output-parallel direct current transformer suitable for a medium voltage direct current power distribution network and the control method thereof realize high efficiency of the direct current transformer, and the power is adjustable.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a novel combined input-series-output-parallel (ISOP) DC transformer suitable for a medium-voltage DC distribution network and a control method thereof. Background technique [0002] As an important branch of power electronics integration technology, the multi-converter series-parallel system has been a research hotspot in recent years. Since the multi-module series-parallel system has the advantages of reducing development difficulty, facilitating expansion, realizing system redundancy, and high reliability, it is widely used in systems such as distributed power generation, power electronic transformers, and uninterruptible power supplies. For multi-converter series-parallel systems, systems with different series-parallel combinations are used in different situations. Taking the ISOP system as an example, it is suitable for high voltage input and high curre...

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Problems solved by technology

For the LC resonant DC transformer, when the open-loop operation is at the resonance point, it does not have the ability to control the output voltage and power, but due to its characteristics of zero-current switching, its switching loss is low, so the efficiency of the converter is high; for DAB As far as the type DC transformer is concerned, it can effectively control the output voltage or output power of the converter by controlling the direction and size of the phase shift angle. LC resonant converter

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