Core converter for building bipolar DC microgrid and control method of core converter

Abstract

The invention discloses a core converter for building a bipolar DC microgrid. The core converter is taken as an interface converter of a high-voltage AC distribution network and a low-voltage bipolar DC microgrid. The core converter comprises three parts of an input filter, a rectifier stage and an isolation stage; and a modular design is adopted. An H-bridge cascade structure is adopted by the rectifier stage; an improved three-port active full-bridge structure is adopted by the modular isolation stage; and output buses are correspondingly connected in parallel, thereby achieving matching of grid voltage and power at two sides of the converter. The invention further discloses a control method of the converter. Vector control of zero-sequence voltage injection is adopted by the rectifier stage; and voltage and current double closed-loop decoupling phase-shifting control is adopted by the isolation stage. According to the core converter, energy can be freely exchanged between the distribution network and the microgrid and between two buses of the bipolar DC microgrid; and functional integration of traditional power frequency transformer, rectifier and voltage balancer for building the bipolar DC microgrid is achieved, so that the building mode of the bipolar DC microgrid is optimized and the power density of building equipment is improved.

Description

technical field [0001] The invention relates to the technical field of power electronic converters, in particular to an interface converter for constructing a bipolar DC microgrid. Background technique [0002] The DC microgrid with bipolar power supply has advantages in many aspects, such as photovoltaic, fuel cell and other new energy access efficiency, data center and computer room power supply efficiency, load and micro-source access flexibility, power supply reliability, and system grounding. Show innate advantages. However, its construction has particularities compared with other types of DC microgrids, which are specifically manifested in the structure of the microgrid neutral line and the balance of the neutral line voltage. Due to the different access methods of loads and micro-sources in the bipolar DC microgrid, it will cause unbalanced bipolar mounted power, which will lead to unbalanced neutral line voltage. For example, one load is connected between the posit...

AI Technical Summary

Problems solved by technology

[0005] In order to overcome the above-mentioned difficulties and deficiencies in the construction of bipolar DC microgrids, the present invention proposes a new converter topology and control method that integrates power frequency transformers, rectifiers, and voltage balancers. The core converter of the interconnection interface between the power grid and the low-voltage bipolar DC microgrid, thereby optimizing the construction method of the bipolar DC microgrid and improving the power density of the equipment

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