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Modularized multi-level converter loss optimization method based on optimal control

A modular multi-level, optimization method technology, applied in output power conversion devices, AC power input into DC power output, electrical components, etc. The current stress increases and other problems, so as to improve the operating life and reliability, ensure the capacitor voltage balance, and reduce the loss difference.

Pending Publication Date: 2022-07-29
SOUTHEAST UNIV
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  • Application Information

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Problems solved by technology

[0002] In recent years, with the rapid development of power electronics technology, modular multilevel converters have become the most attractive converter topology in high-voltage and high-power systems. With the advantages of high efficiency, low harmonic content of the output voltage on the AC side, and redundant control, it has been widely used in fields such as flexible DC power transmission, medium and high voltage motor drives, and large-scale new energy grid connection. The flowmeter is composed of a large number of sub-modules. In the actual operation process, the loss distribution of each sub-module often appears uneven. The thermal stress difference caused by the uneven loss will lead to the difference in the life of the MMC sub-modules, thereby reducing the reliability of the MMC. , so loss optimization is one of the important challenges to improve the reliability of MMC
[0003] At present, the loss optimization of modular multilevel converters is often achieved by changing the topology of sub-modules or injecting circulating currents. There are problems such as increased construction costs of modular multilevel converters and increased device current stress. The application of the above method in practical engineering is limited. Therefore, a loss optimization method for modular multilevel converter based on optimal control is now proposed

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  • Modularized multi-level converter loss optimization method based on optimal control
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  • Modularized multi-level converter loss optimization method based on optimal control

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Embodiment Construction

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] like figure 1 As shown, a method for optimizing the loss of a modularized multilevel converter based on optimal control, the method for optimizing the loss of a modularized multilevel converter includes the following steps:

[0042]Step 1: Monitor in real time the number of sub-modules n(k) and the bridge arm current i of each bridge arm to be put into the control period k in which the modular multilevel converter is currently ...

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Abstract

The invention discloses a modularized multi-level converter loss optimization method based on optimal control, which relates to the technical field of multi-level power electronic converters and comprises the following steps of: monitoring the number of sub-modules to be put into each bridge arm, bridge arm current and sub-module capacitor voltage of the modularized multi-level converter in a current control period in real time; establishing an objective function of loss optimization, and setting constraint conditions; solving a sub-module input / removal state capable of enabling the target function to reach the minimum; according to the method, not only can the capacitor voltage of the sub-modules be balanced, but also the loss difference between the sub-modules in the modularized multi-level converter can be effectively reduced, so that the loss of the sub-modules can be effectively reduced, and the reliability of the converter is improved. In addition, extra voltage and current stress cannot be brought to devices, the cost of the modular multilevel converter does not need to be increased, and the modular multilevel converter has high practical value in the aspect of prolonging the service life and improving the reliability of the modular multilevel converter.

Description

technical field [0001] The invention relates to the technical field of multilevel power electronic converters, in particular to a loss optimization method for a modularized multilevel converter based on optimal control. Background technique [0002] In recent years, with the rapid development of power electronics technology, modular multilevel converters have become the most attractive converter topology in high-voltage and high-power systems. It has the advantages of high efficiency, low harmonic content of the output voltage on the AC side, and can realize redundant control. The current flow device is composed of a large number of sub-modules. In the actual operation process, the loss distribution of each sub-module often appears uneven. The thermal stress difference caused by the uneven loss will lead to the difference in the life of the MMC sub-modules, thereby reducing the reliability of the MMC. , so loss optimization is one of the important challenges to improve MMC ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483
CPCH02M7/483
Inventor 邓富金侯洁华喻强
Owner SOUTHEAST UNIV
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