Fan-shaped vector control method capable of suppressing series connection combination type MMC ring current

A vector control and combination technology, which is applied in the control/regulation system, regulating electrical variables, and output power conversion devices, etc., can solve the problem of the unanalyzed DC side current relationship, higher requirements for current bearing capacity, and increased peak-to-peak value of input current. It can reduce the size and cost, improve the input current waveform, and reduce the peak-to-peak value.

Active Publication Date: 2017-08-01
SOUTHEAST UNIV
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Problems solved by technology

[0005] However, for the series combined MMC on the DC side, a large number of literatures have not yet analyzed the relationship between the series MMC and the DC side current.
In fact, the modular multi-level sub-module (SM) contains a capacitor. According to the characteristics of the capacitor itself, the energy stored in the capacitor fluctuates, and the energy fluctuation frequency is twice the switching frequency. Therefore, the combined MMC and power supply side The current will be superimposed with the current of twice the switching frequency. With the incr

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  • Fan-shaped vector control method capable of suppressing series connection combination type MMC ring current
  • Fan-shaped vector control method capable of suppressing series connection combination type MMC ring current
  • Fan-shaped vector control method capable of suppressing series connection combination type MMC ring current

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Embodiment Construction

[0031] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] like figure 1 Shown is a single-module DC / DC converter. The left side uses MMC in series to form an H-bridge structure, and the right side uses an H-bridge structure composed of IGBTs. The left and right sides are connected by intermediate frequency transformers. The single-module DC / DC converter adopts a phase-shift control strategy, and the MMC side adopts the nearest level modulation strategy.

[0033] combine figure 1 , constituted as figure 2 The series-input and parallel-output DC / DC converters shown form a series-type MMC structure on the left side.

[0034] like image 3 Shown is the dual-loop control strategy adopted to ensure the power balance between the modules and the stability of the output voltage after cascading in parallel, the voltage outer loop and the current inner loop, and the final output is ...

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Abstract

The invention discloses a fan-shaped vector control method capable of suppressing series connection combination type MMC ring current. On the basis of a classical modular multilevel converter (MMC) series connection structure, a relation between the series connection combination type MMC and a power supply is analyzed to obtain a theory that the current between the series connection combination type MMC and the power supply is overlaid with double switching frequency ring current, so that a fan-shaped vector control strategy is proposed. By virtue of the fan-shaped vector control method, the double switching frequency ring current overlaid between the series connection combination type MMC and the power supply can be suppressed and input current fluctuation can be reduced; and meanwhile, the control strategy is verified in a serial-in parallel-out type MMC-H bridge DC/DC conversion module, and high practicability, simple control and high reliability are shown.

Description

technical field [0001] The invention relates to a field of modular multilevel converters and direct current conversion, in particular to a fan-shaped vector control method for suppressing the circulating current of series combined MMCs. Background technique [0002] Modular multilevel converter (MMC) is a new type of converter suitable for medium and high voltage applications. This structure has great advantages. Compared with cascaded bridge multilevel topology, it has a common DC bus and good Four-quadrant working performance and other characteristics. The structure of each sub-module is relatively simple, easy to control, and can be expanded infinitely, especially suitable for high-voltage and large-capacity fields. [0003] With the rise of flexible DC transmission in recent years, the DC distribution network will continue to develop in the future. As an important part of DC distribution network, high-voltage and high-power DC / DC converters are being studied in depth. ...

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Application Information

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IPC IPC(8): H02M3/335H02M7/483H02M1/32
CPCH02M1/32H02M3/33561H02M3/33592H02M7/483H02M1/325H02M7/4835
Inventor 梅军管州丁然王创何梦雪
Owner SOUTHEAST UNIV
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