Three-port DC-DC converter topological structure and control method thereof

Abstract

The invention discloses a three-port DC-DC converter topological structure and a control method thereof. The three-port DC-DC converter topological structure comprises an input port and two output ports, the structure of one input port is an MMC circuit and is used for bearing high voltage of a medium-voltage direct-current power grid; the MMC circuit has two phases, each phase is composed of an upper bridge arm and a lower bridge arm, each bridge arm comprises n sub-modules with the same structure, and each sub-module adopts a half-bridge type sub-module topological structure; the two output ports are DAB circuits and comprise a first low-voltage side DC / AC full-bridge circuit and a second low-voltage side DC / AC full-bridge circuit; wherein the input port and the output ports are connected through the isolation transformer. According to the three-port DC-DC converter topological structure, energy transmission from an MVDC side to an LVDC side can be realized; the voltage change rate can be reduced, the impact of instantaneous voltage on the switch is reduced, and stable power transmission is realized; each-phase ring current is reduced, and power loss is reduced.

Description

technical field [0001] The invention belongs to the technical field of medium and low voltage DC-DC converter topology and control, and in particular relates to a three-port DC-DC converter topology and a control method thereof. Background technique [0002] Non-isolated multi-port DC-DC converters have attracted much attention due to their high reliability and easy use. and orientation, this topology can only be used at low voltages. Some researchers introduce high-frequency transformers (HFT) to establish electrical isolation between the primary side and the secondary side; it is undeniable that high-frequency trading improves power density, realizes bidirectional transmission of power, and overcomes some shortcomings of non-isolated circuits . [0003] According to the characteristics of different ports, there are many types of isolated multi-port DC-DC topologies; considering the voltage level, a modular multi-level converter is selected as the input to realize medium ...

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Problems solved by technology

[0003] According to the characteristics of different ports, there are many types of isolated multi-port DC-DC topologies; considering the voltage level, a modular multi-level converter is selected as the input to realize medium voltage direct current (MVDC) side to low voltage direct current (LVDC) side energy transmission; due to the large number of sub-modules, it is necessary to consider the complexity and efficiency of control, the insertion and bypass of sub-modules will lead to a huge voltage change rate and huge power loss

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