Step-type modular multilevel converter and control method thereof

A modular multi-level and control method technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve problems such as limiting the smoothness of the output waveform and the complexity of the control process. Achieve the effect of stable capacitor voltage, smooth output waveform, and reduce product cost

Active Publication Date: 2018-12-28
QINGDAO UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The greater the number of sub-modules, the more complex the process of controlling the MMC. Therefore, in practical applications, the number of sub-modules of the MMC will not be too large, which also limits the smoothness of the output waveform.

Method used

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  • Step-type modular multilevel converter and control method thereof
  • Step-type modular multilevel converter and control method thereof

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Embodiment Construction

[0019] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0020] See figure 1 , which is a topological structure diagram of an embodiment of a step-tuned modular multilevel converter based on the present invention. Among them, the step-tuned modular multilevel converter refers to a modular multilevel converter in which the theoretical capacitor voltages of n sub-modules connected in series satisfy the relationship of 1:2:...:2n, where n is greater than 1 of natural numbers.

[0021] Such as figure 1 As shown, the modular multilevel converter of this embodiment includes an upper bridge arm and a lower bridge arm. The structures of the upper bridge arm and the lower bridge arm are symmetrical. Only the upper bridge arm is taken as an example to describe the structure of one bridge arm. Specifically, the ...

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Abstract

The invention discloses a step-type modular multilevel converter and a control method thereof. The step-type modular multilevel converter comprises an upper bridge arm, a lower bridge arm and a sub-module control unit, wherein the upper bridge arm and the lower bridge arm both comprise n sub-modules connected in series, and the theoretical capacitance voltages of the n sub-modules satisfy V1: V2:...: Vn=1: 2:...: 2n; the control method comprises: determining the number n of the sub-modules connected in series in each bridge arm, determining the formula of theoretical total output voltage V inaccordance with the step control strategy, giving all the values of the coefficients when V takes different values, determining the actual values of the coefficients, determining a control signal forcontrolling the switching state of each sub-module according to the actual values of the coefficients, and controlling the switching state of the sub-module according to the control signal. By adopting the invention, the purpose of obtaining more output levels by adopting a small number of sub-modules can be realized.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a step-tuned modular multilevel converter and a control method thereof. Background technique [0002] Modular multilevel converter, referred to as MMC, is a relatively new topology type of voltage source converter, which is composed of multiple cascaded sub-modules (Sub-Module, SM). These sub-modules can be Half-bridge sub-module or full-bridge sub-module. MMC has become an advanced power electronic converter due to its advantages of easy modular design, flexible manufacturing and upgrading, and convenient maintenance, and is widely used in flexible direct current transmission systems. [0003] In a traditional MMC, all the sub-modules SM have the same output voltage. Therefore, there are limited ways to combine the outputs of the sub-modules in the upper and lower bridge arms to form the final required level. To obtain more output levels and make the outp...

Claims

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Application Information

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Patent Type & AuthorityApplications(China)
IPC IPC(8): H02M7/483
CPCH02M7/483H02M7/4835
Inventor于飞朱瑞峰刘喜梅徐凌伟童刚董新利
OwnerQINGDAO UNIV OF SCI & TECH