High-frequency link technology-based isolated modular cascaded converter

Abstract

The invention discloses a high-frequency link technology-based isolated modular cascaded converter, which is capable of achieving conversion from low voltage DC to high voltage DC. Single-phase and three-phase topological structures of the converter are formed by single-stage high-frequency isolation modules, wherein the three-phase structure can be in star connection or delta connection; each module comprises an upper submodule and a lower submodule; and each submodule comprises four parts, namely a front-stage active H bridge, a high-frequency transformer, a back-stage active H bridge and avoltage clamping circuit. The high-frequency link technology-based isolated modular cascaded converter belongs to single-stage power conversion, so that high voltage sides of various modules do not need to be supported by a capacitor any more; and compared with a two-stage modular cascaded converter, the high-frequency link technology-based isolated modular cascaded converter has the advantages that use of the capacitor can be reduced, the volume and the cost of a device are reduced, and meanwhile, the problems, such as secondary side current commutation and voltage spike of a traditional single-stage converter are solved.

Description

technical field [0001] The invention relates to an isolated modular cascaded power conversion technology, in particular to an isolated modular cascaded converter based on high-frequency link technology. Background technique [0002] Power electronic transformers are more and more widely used in new energy grid connection. In order to improve the voltage level of the high-voltage side, the current power electronic transformers widely adopt modular cascaded structures, such as cascaded H-bridge type. According to the number of stages of power conversion, most of the modular cascaded structures adopt two-stage power conversion system such as figure 1 As shown, the problem of the two-stage power conversion is that a large number of voltage stabilizing capacitors are required on the high-voltage side of each module to buffer the secondary power fluctuation of the single-phase system, which makes the device large in size, low in power density, and high in cost; at the same time, ...

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Problems solved by technology

[0003] In order to solve the above problems, the present invention provides an isolated modular cascaded converter based on high-frequency link technology. The converter belongs to single-stage power conversion, so the high-voltage side of each module no longer needs capacitor support and voltage equalization control, and at the same time It also solves the problems of secondary side commutation and voltage spikes of traditional single-stage converters, and can realize power conversion between low-voltage DC and high-voltage AC

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