Control Method of Bridge Arm Current in Modular Multilevel Converter

A modular multi-level, converter bridge 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 control command deviation, control command bias, etc. The voltage imbalance of the upper and lower bridge arm sub-modules can reduce the stress difference, prolong the service cycle, and suppress the bridge arm current asymmetry.

Active Publication Date: 2016-05-04
NR ELECTRIC CO LTD +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] 1. There is a bias in the control instructions issued by the upper controller;
[0008] 2. The voltage of the sub-modules of the upper and lower bridge arms is unbalanced, and the voltage generated by the actual superposition deviates from the control command

Method used

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  • Control Method of Bridge Arm Current in Modular Multilevel Converter
  • Control Method of Bridge Arm Current in Modular Multilevel Converter
  • Control Method of Bridge Arm Current in Modular Multilevel Converter

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Embodiment Construction

[0028] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] attached figure 2 It is a schematic diagram of a control method for superimposing an opposite additional conduction number instruction in the upper and lower bridge arm control instructions. I bu_rms and I bd_rms are the fundamental current RMS values ​​of the upper bridge arm and the lower bridge arm of a certain phase unit, I diff Is the effective value of the fundamental wave of the lower bridge arm current I bd_rms and the fundamental RMS value of the upper arm current I bu_rms difference. Ideally, the difference is about 0 due to the symmetrical currents of the upper and lower bridge arms; diff May not be 0. ΔN u and ΔN d Respectively, additional instructions for increasing or decreasing the number of conductions of sub-modules, and the additional instructions for the number of conductions ΔN i...

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Abstract

The invention discloses two control methods for the bridge arm current of a modular multilevel converter, which improve the basic control method, by superimposing opposite additional conduction number instructions or additional voltage instructions in the upper and lower bridge arm control instructions, Realize reducing or even suppressing the bridge arm current asymmetry caused by the bias of the control command issued by the upper controller or the voltage imbalance of the upper and lower bridge arm sub-modules, and reducing the stress difference between the upper and lower bridge arms.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission in power systems, and in particular relates to a control method for bridge arm current of a modular multilevel converter. Background technique [0002] Modular multi-level converter is a new type of converter suitable for high-voltage applications that has attracted much attention in recent years. It adopts the method of cascading sub-modules. The AC voltage output by the converter is close to a sine wave, thereby reducing the harmonic content in the output voltage. Its appearance solves the problem of series voltage equalization in the two-level voltage source converter, and has broad application prospects. [0003] The schematic diagram of the main circuit topology of the three-phase modular multilevel converter (MMC) is as follows: figure 1 As shown in (a), it contains 3 phase units, each phase unit includes two upper and lower bridge arms, and each bridge arm is c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/72
CPCH02M7/4835
Inventor 汪楠楠田杰董云龙刘海彬卢宇胡兆庆李钢张静陆翌申斌胡列翔李继红朱承治
Owner NR ELECTRIC CO LTD
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