Multilevel converter with triangular modular structure

Abstract

The invention discloses a multilevel converter with a triangular modular structure. The converter comprises n stages of series combination circuits, each stage of combination circuit comprises a plurality of DC-DC modules, and the number of the modules is linearly decreased from the first stage of combination circuit to the nth stage of combination circuit. The modular multilevel converter can realize high-voltage, high-power and high-gain direct-current conversion under the condition of ensuring current sharing and voltage sharing of each DC-DC module. According to the modular multilevel converter, the voltage level, the voltage gain and the power capacity can be improved by expanding the number of the combination circuit modules at all levels, and the modular multilevel converter has the advantages of high power density, low loss, module self-energy-taking driving and the like. All DC-DC modules in the converter can realize self-energy-taking driving and control of soft switching and switching tubes, have completely identical circuit structures and electrical parameters, and can realize standardized and large-scale production.

Description

technical field [0001] The invention belongs to the field of power transmission and distribution of power systems, and in particular relates to a multilevel converter with a triangular modular structure. Background technique [0002] At present, all countries are vigorously developing new energy sources, such as solar energy, tidal energy, wind energy, etc. These new energy sources are renewable and non-polluting, and are the main direction of future energy development. For the new energy power grid transmission system, the DC grid has the characteristics of large transmission power capacity, small loss, long transmission distance, and good stability, and has been widely used. Therefore, high-gain, high-voltage, low-loss DC converters have become the current scholar one of the directions of our research. [0003] Modular Multilevel Converter (MMC) can realize the conversion of different voltage levels, so as to reduce the voltage stress of power devices in the grid. MMC ci...

AI Technical Summary

Problems solved by technology

MMC circuits include isolated and non-isolated types. The isolated MMC circuit usually uses a half-bridge module or a full-bridge module, and the voltage conversion is realized through an isolation transformer. However, as the voltage level continues to rise, this type of topology is difficult to meet the transformer Insulation, high frequency and other requirements

Compared with isolated MMC, non-isolated MMC can be mainly divided into switched capacitor type MMC, coupled inductor type MMC, and resonant boost type MMC. However, the above types have low utilization rate, switching device voltage stress, current stress Uneven distribution, not easy to expand, unable to realize soft switching, unable to realize self-energy driving and other problems

Therefore, the existing MMC circuit cannot be applied to the field of power transmission and distribution of power systems driven by high voltage, high gain, large capacity, high power density, low loss, and self-capturing to a certain extent.

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