Hybrid topology of cascaded h-bridge multilevel converter and its control method

Abstract

The present invention uses the high-frequency module and low-frequency module separated by the mixed frequency pulse width modulation, and the high-frequency branch and the power frequency branch separated by the unipolar modulation to propose a cascaded H-bridge multi-level converter hybrid Topology structure and control method, first adopt Si IGBT with small transmission loss for power frequency branch, and then provide two solutions with low switching loss for high frequency branch, including using SiC MOSFET in parallel and using SiC MOSFET and Si IGBT in parallel, Finally, the Si IGBT is used as the switching device of the low-frequency module, and the switching function is regularly rotated in the half power frequency cycle. The hybrid topological structure and control method provided by the invention solve the problems of large power loss and uneven distribution of cascaded H-bridge multilevel converters and uneven intermediate direct current voltage in the prior art.

Description

technical field [0001] The invention belongs to the technical field of loss reduction and energy saving of power electronic converters and loss equalization control, and relates to a hybrid topology structure of a cascaded H-bridge multilevel converter and a control method thereof. Background technique [0002] With the large-scale application and development of power electronic technology, power electronic equipment has become the core of high-quality and efficient use of electric energy in various fields of the national defense industry, especially large-capacity equipment. The cascaded H-bridge multi-level structure is favored in medium-high voltage and high-power applications because of its good output waveform quality and easy modular expansion. Its control effect and conversion efficiency play a vital role in improving the energy utilization rate of large-capacity equipment. [0003] The cascaded H-bridge multi-level topology uses switching devices with lower withstan...

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Problems solved by technology

[0004] In order to achieve the above object, the present invention provides a hybrid topology structure and control method of a cascaded H-bridge multilevel converter, which solves the uneven distribution of heat loss of each module of the cascaded H-bridge multilevel structure in the prior art, The problem of unbalanced intermediate DC voltage

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