A High Power Density Multiport Power Electronic Transformer Topology

Abstract

The invention discloses a high-power-density multi-port power electronic transformer topology comprising a high-voltage-side modular multilevel converter, an intermediate-side resonant high-frequencyconverter, and a low-voltage-side direct-current bus. Positive and negative direct-current buses of the modular multilevel converter are connected with two blocking resonant capacitors of the high-frequency converter and an alternating-current bus of the modular multilevel converter is connected with an alternating-current resonant capacitor of the high-frequency converter to form an upper resonant loop and a lower resonant loop. An upper bridge arm and a lower bridge arm of the modular multilevel converter output inverting high-frequency alternating currents and the energy is transmitted to the lower voltage side through the resonant loops in a high-frequency mode. Compared with the existing multi-port power electronic transformers with the high-voltage alternating current bus, the high-voltage direct current bus, and the low-voltage direct-current bus, the high-power-density multi-port power electronic transformer topology enables the number of high-frequency transformers, sub modules, capacitors, and switch devices to be reduced substantially and does not need any high-frequency trap filter of the direct-current bus, so that the equipment size and cost are reduced substantiallyand the equipment efficiency and power density are improved.

Description

Technical field [0001] The invention belongs to the technical field of power electronics, and particularly relates to a high-power density multi-port power electronic transformer topology. Background technique [0002] Power electronic transformers are power electronic devices with functions such as voltage conversion, reactive power compensation, unbalance control, and power quality management. Among them, multi-port power electronic transformers with high-voltage AC, high-voltage DC, and low-voltage DC are suitable for AC / DC hybrid power grids, which facilitate the access and consumption of renewable energy, and also help improve the operating efficiency and reliability of the power grid. The multi-port power electronic transformer has the function of an electric energy router in the energy Internet. [0003] There are many types of power electronic transformer structures. Among them, the AC / DC / DC type structure facilitates the formation of high-voltage AC, high-voltage DC and l...

AI Technical Summary

Problems solved by technology

In medium and high voltage applications, due to the insufficient withstand voltage capability of power switching devices, power electronic transformers need to adopt a modular structure. There are many modules; on the other hand, in the DC / DC high-frequency conversion isolation link of the existing AC / DC / DC power electronic transformer, the high-voltage side sub-modules may be connected to the high-voltage DC bus, which needs to withstand high DC voltage to cause sub-modules There are many modules, or they are connected to the DC side of the sub-modules of the AC / DC link. The two sub-modules correspond one to one, and the number of sub-modules is also large.

The large number of sub-modules greatly increases the volume, cost and control complexity of the device, reduces the efficiency and power density of the device, and is not conducive to the popularization and application of power electronic transformers

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