Modular multilevel converter for eliminating low-frequency voltage fluctuation

A modular multi-level, low-frequency voltage technology, applied in the direction of adjusting electrical variables, converting DC power input to DC power output, and converting AC power input to DC power output, can solve the problem of increasing the current stress of the bridge arm and making it difficult to meet MMC requirements. Low-frequency operation, motor adverse effects and other issues, to achieve power balance, easy maintenance and debugging, reduce the effect of adverse effects

Inactive Publication Date: 2017-05-10
XI AN JIAOTONG UNIV
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Problems solved by technology

However, this method will increase the current stress of the bridge arm, and at the same time, the injected common-mode voltage will have an adverse effect on the motor, which is still difficult to meet the needs of MMC with high-torque load starting and low-frequency operation

Method used

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  • Modular multilevel converter for eliminating low-frequency voltage fluctuation
  • Modular multilevel converter for eliminating low-frequency voltage fluctuation
  • Modular multilevel converter for eliminating low-frequency voltage fluctuation

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Embodiment 1

[0030] use as figure 1 The topological structure includes a traditional dual-star half-bridge MMC and a dual-active bridge DAB module. The DAB power conversion unit includes four ports and has the function of energy bidirectional flow;

[0031] The specific MMC sub-module is a half-bridge composed of two fully-controlled devices, and its structure is as follows image 3 The half-bridge represented by SM is shown. A capacitor bank with a certain capacity is connected in parallel between the two terminal lines of the DC side of the two half bridges;

[0032] The number of cascaded power converters is determined by the input voltage level and the level of the selected power electronic devices. For example, when the DC side voltage is 11kV, when the switching device 1.7kV / 400A IGBT is selected and the DC side is set to 1.1kV, each The bridge arm requires 10 converters to be cascaded.

[0033] The DAB power conversion unit is divided into three components: as a high-frequency DC...

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Abstract

The invention discloses a modular multilevel converter for eliminating low-frequency voltage fluctuation. The low-frequency voltage fluctuation of a sub-module during low-frequency dragging of the modular multilevel converter can be eliminated, sub-modules with corresponding serial numbers in each phase of upper and lower bridge arms are connected with the same DAB power conversion unit, the DAB power conversion unit transmits fluctuation energy in the corresponding module, the power balance of the corresponding sub-modules of the upper and lower bridge arms can be realized, the modular multilevel converter disclosed by the invention can be entirely modularized, thereby being high in reliability and being convenient to maintain and debug; no high-frequency common mode voltage needs to be injected just like the traditional voltage fluctuation control method, therefore the control calculation is simple, and meanwhile, adverse effects to a motor are reduced; and no harmonic circulation component needs to be injected in the bridge arms, thereby reducing the voltage stress and the loss of the bridge arms.

Description

technical field [0001] The invention belongs to the technical field of modular multilevel converters, and in particular relates to a modular multilevel converter for eliminating low-frequency voltage fluctuations. Background technique [0002] With the wide application of high-power power electronic conversion devices, multi-level conversion technology has been developed rapidly. Modular Multilevel Converter (MMC) is a novel multilevel voltage source converter. Since it was proposed in early 2000, it is easy to expand and assemble due to its modular characteristics. And high-quality output and high voltage level can be obtained, so MMC is a research hotspot in recent years, and has obvious advantages in the field of medium and high voltage applications. [0003] At present, MMC has been widely used in the field of High Voltage Direct Current (HVDC), and many lines have been put into operation, such as Trans Bay Cable project, ±200kV, 400MW, each bridge arm has 200 sub-modul...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M3/335H02M1/12
CPCH02M1/12H02M3/33576H02M7/483H02M1/0038
Inventor 刘进军宋曙光欧阳少迪陈星星
Owner XI AN JIAOTONG UNIV
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