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Capacitor voltage self-balancing circuit of modularized multi-level converter

A modular multi-level, capacitive voltage technology, applied in the field of multi-level conversion, can solve the problems of large size and complex control, and achieve the effect of simple circuit structure, simple control and convenient control

Active Publication Date: 2014-03-12
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method requires an additional external complex isolated DC-DC power circuit, which is large in size and complex in control

Method used

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  • Capacitor voltage self-balancing circuit of modularized multi-level converter
  • Capacitor voltage self-balancing circuit of modularized multi-level converter
  • Capacitor voltage self-balancing circuit of modularized multi-level converter

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] image 3 A multi-level converter capacitor voltage self-balancing circuit of cascaded common negative bus half-bridge of the present invention is given. In the figure, the electronic switch unit 2 is composed of a power switch tube Q21 with an anti-parallel diode. The switch port of the switch unit 2 is directly connected between the positive DC bus bars +d1 and +d2 of the first sub-module 1-1 and the second sub-module 1-2 of two adjacent common negative bus half-bridges, that is, the power The emitter and collector of the switch tube Q21 are respectively connected to the positive DC bus +d1 and +d2 of the first sub-module 1-1 and the second sub-module 1-2; the switching of the power switch Q21 is controlled by the control unit The output signal G1 of 3 is controlled; the input signal K11 of the control unit 3 comes from the switch control signal of the power switch T2 of the first sub-module 1-1, G1=K11, wherein logic "1" means that the control switch is turned on, log...

Embodiment 2

[0055] Figure 3a A multilevel converter capacitor voltage self-balancing circuit of a cascaded common positive bus half bridge of the present invention is given. In the figure, the electronic switch unit 2 is composed of a power switch tube Q22 with an antiparallel diode. The switch port of the switch unit 2 is directly connected between the negative DC buses -d1 and -d2 of the first submodule 1-1 and the second submodule 1-2 of the two adjacent common negative bus half bridges, that is, the power The collector and emitter of the switching tube Q22 are respectively connected to the negative DC bus bars -d1 and -d2 of the first sub-module 1-1 and the second sub-module 1-2; the switching of the power switching tube Q22 is controlled by the control unit The output signal G2 of 3 is controlled; the input signal K12 of the control unit 3 comes from the switch control signal of the power switch T1 of the first sub-module 1-1, G2=K12, wherein logic "1" means that the control switch ...

Embodiment 3

[0057] Figure 4 A cascaded H-bridge multilevel converter capacitor voltage self-balancing circuit of the present invention is given. In the figure, the electronic switch unit 2 is composed of two power switch tubes Q11 and Q21 with anti-parallel diodes in reverse series to form a bidirectional A controllable switch, the switch port of the electronic switch unit 2 is directly connected between the positive DC bus bars +d1 and +d2 of the first sub-module 1-1 and the second sub-module 1-2 of two adjacent H-bridges, That is, the collectors of the power switch tubes Q11 and Q21 are respectively connected to the positive DC bus bars +d1 and +d2 of the first sub-module 1-1 and the second sub-module 1-2; the power switch tubes Q11 and Q21 The on-off is controlled by the output signal G1 of the control unit 3; the input signals K11 and K21 of the control unit 3 are respectively from the switch control signal of the power switch T2 of the first sub-module 1-1 and the switch control sig...

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Abstract

The invention relates to a capacitor voltage self-balancing circuit of a modularized multi-level converter. The capacitor voltage self-balancing circuit comprises an electronic switch unit, at least two submodules, at least one control unit and at least one current limiting unit, wherein each submodule comprises a plurality of power switch tubes, two output ends and a pair of positive / negative direct-current buses; the first output end of each first submodule is connected with the second output end of the second submodule; the direct-current sides of the submodules are connected to the switching ends of the electronic switch units; a switching control signal is connected to the input end of each control unit; the output of the at least one control unit is connected to the control end of the corresponding electronic switch unit; the output end of the at least one current limiting unit is connected to the input end of the at least one control unit; whether the switching current in the electronic switch unit is within an allowed range is determined; the electronic switch is controlled to be closed or opened, so that the direct-current buses of the adjacent submodules are automatically connected in parallel in a proper period of time; and therefore, the purpose of capacitor voltage self-balancing of the submodules is achieved.

Description

technical field [0001] The invention relates to a capacitor voltage self-balancing circuit of a modular multilevel converter, which belongs to the technical field of multilevel conversion. Background technique [0002] Modular multilevel converter (MMC) topology adopts cascaded and modular structure, and can obtain multi-level ladder voltage without direct series connection of power devices, with lower dU / dt and lower Voltage harmonic content has broad application prospects in medium / high voltage large capacity systems. The MMC is composed of multiple power chains, and each power chain is formed by cascading N half-bridge or H-bridge sub-modules, and the DC side of each sub-module is connected in parallel with the same capacitor. Since the DC-side capacitors of each sub-module of the modular multilevel converter are in a floating state, the capacitors of each sub-module will be charged and discharged differently during operation, which will lead to an imbalance problem of c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M7/5387
Inventor 王广柱王明达
Owner SHANDONG UNIV