Modular multi-level full-bridge resonant power electronic transformer topology

Abstract

The invention belongs to the technical field of power electronics, and in particular relates to a modular multi-level full-bridge resonant power electronic transformer topology, which specifically includes three phases on the high-voltage side of a three-phase star-connected structure, each phase has the same structure, and each phase contains Nt subunits and Nt low-voltage side full-bridge modules; each subunit contains a resonant LC, a high-frequency transformer, and a high-voltage side MMC full-bridge module for each phase; in two adjacent subunits, the MMC modules each generate a part of the base frequency phase voltage Output, and produce high-frequency square waves with equal amplitude and opposite phase at the same time. The high-frequency square wave is filtered by the bridge arm resonance LC, and then isolated and stepped down by the high-frequency transformer, and rectified by the low-voltage side H-bridge module to the low-voltage DC bus. Compared with the high-voltage side and intermediate-level topology of traditional power electronic transformers, this topology can save the number of high-frequency transformers, modules, capacitors and switches, and has a good output waveform.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a modular multilevel full-bridge resonant power electronics transformer topology. Background technique [0002] A power electronic transformer is a power electronic device with functions such as voltage conversion, reactive power compensation, unbalance control, and power quality management. There are many types of power electronic transformer topologies, the common ones are AC / AC type, AC / DC / DC type and AC / DC / DC / AC type. The AC / AC topology belongs to the matrix structure, and the coupling degree between the bridge arms is high, which affects the quality of the output waveform; the AC / DC / DC type has capacitors for decoupling, and the output waveform quality is better. At the same time, this topology can Provide high-voltage and low-voltage DC busbars to facilitate grid interconnection; AC / DC / DC / AC type adds a low-voltage DC side inverter link on the basis o...

AI Technical Summary

Problems solved by technology

[0003] Compared with traditional transformers, power electronic transformers have complex structures, many types and quantities of components, low power density, and high overall cost

The AC / AC type with a lower number of stages in the above-mentioned power electronic transformer structure is difficult to ensure a good waveform, and the AC / DC / DC / AC type with a larger number of stages has a complex structure

Images