Method for controlling voltages of direct current capacitors of six-switching-group or nine-switching-group MMC converter

A voltage control method and DC capacitor technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve the problem of unsuitable dual-output single-phase six-switch group MMC converters and dual-output Three-phase nine-switch group MMC converter and other problems, to achieve the effect of high waveform quality and solve the problem of voltage equalization

Active Publication Date: 2014-08-27
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the current control method of the DC capacitance of the MMC converter is not suitable for the dual-output single-phase six-switch group MMC converter and the dual-output three-phase nine-switch group MMC converter

Method used

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  • Method for controlling voltages of direct current capacitors of six-switching-group or nine-switching-group MMC converter
  • Method for controlling voltages of direct current capacitors of six-switching-group or nine-switching-group MMC converter
  • Method for controlling voltages of direct current capacitors of six-switching-group or nine-switching-group MMC converter

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Embodiment Construction

[0019] In order to further illustrate the content and characteristics of the present invention, the specific embodiments of the present invention will be described below in conjunction with the accompanying drawings, but the implementation of the present invention is not limited thereto.

[0020] refer to figure 1 , dual-output single-phase six-switch group MMC converter, including DC power supply U dc , the first bridge arm, the second bridge arm, the first load and the second load; the first bridge arm and the second bridge arm are controlled by the upper switch group H 1 、H 2 , Middle switch group M 1 , M 2 , Lower switch group L 1 , L 2 and coupled inductance (L H1 :L L1 , L H2 :L L2 ) in series; the upper switch group H of the first bridge arm 1 consists of N power switching units (SM H11 , SM H12 ,...,SM H1N ) in series, the middle switch group M of the first bridge arm 1 consists of N power switching units (SM M11 , SM M12 ,...,SM M1N ) in series, the l...

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Abstract

The invention provides a method for controlling voltages of direct current capacitors of a six-switching-group or nine-switching-group MMC converter. The method includes the steps of voltage averaging control and voltage balance control. A voltage loop and a current loop are used in the voltage averaging control. The voltage balance control includes voltage balance control over the direct current capacitors of power switch units of upper switching groups, middle switching groups and lower switching groups of bridge arms. The voltages of the direct current capacitors of the power switch units of the upper switching groups, the middle switching groups and the lower switching groups are sampled and stabilized through voltage feedback and PI adjustment. By means of the control method, the voltages of the direct current capacitors of the six-switching-group or nine-switching-group MMC converter are balanced and stabilized, it is guaranteed that the direct current capacitors have dual 2N+1 level alternating current outputs, the quality of waveforms of output currents is high, voltage stress borne by each switch tube in the power switch units is only one Nth of the direct current bus voltage, and the voltage sharing aim of the switch tubes is well achieved.

Description

technical field [0001] The invention relates to the control field of a DC capacitor voltage of a modular combination multilevel (MMC) converter, in particular to a method for controlling the DC capacitor voltage of a six-switch group or nine-switch group MMC converter. Background technique [0002] Both the dual-output single-phase six-switch group MMC converter and the dual-output three-phase nine-switch group MMC converter have two 2N+1 level AC outputs, and the output current waveform is of high quality. The voltage stress is only 1 / N of the DC bus voltage, and at the same time, it can ensure that the voltages of all switching tubes are equal during the working process of the converter, which solves the problem of voltage equalization of the switching tubes. Compared with the existing single-phase six-switch converter and three-phase nine-switch converter, the two outputs of the dual-output single-phase six-switch group MMC converter and the dual-output three-phase nine-s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483
Inventor 张波付坚丘东元
Owner SOUTH CHINA UNIV OF TECH
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