Control method of modular multilevel converter and controller thereof

Abstract

The invention provides a control method of a modular multilevel converter and a controller thereof. The modular multilevel converter comprises 2k bridge arms, wherein k is the phase number of corresponding alternating current, each bridge arm comprises N sub-modules of the same structure, and the control method comprises the steps that the temperature values and the voltage values of the sub-modules of the modular multilevel converter are obtained; for each bridge arm, based on the temperature value and the voltage value of the sub-module of the bridge arm, the current direction of the bridgearm, the number of the sub-modules needing to be conducted in the bridge arm in the control period and the number of the currently conducted sub-modules in the bridge arm, the sub-modules needing to be conducted are determined in the bridge arm in the control period; wherein N is an integer greater than 0, the sub-modules which are determined for each bridge arm and need to be conducted are controlled to be conducted, and the other sub-modules are controlled to be turned off. According to the control method and the controller thereof, switching loss of the sub-modules of the modular multilevelconverter can be effectively reduced.

Description

technical field [0001] The present invention generally relates to the technical field of converters, and more specifically, relates to a control method and a controller for a modular multilevel converter. Background technique [0002] When the modular multilevel converter (MMC) is applied in the field of high-voltage power transmission, a large number (for example, hundreds to thousands) of sub-modules need to be cascaded, and the higher the level of the corresponding DC voltage, the required sub-modules The greater the number of sub-modules, since each sub-module needs to be individually controlled to be turned on or off, therefore, how to effectively reduce the switching loss of the sub-modules has attracted more and more attention. Contents of the invention [0003] An exemplary embodiment of the present invention is to provide a control method of a modular multilevel converter and its controller, so as to solve the large switching loss of the sub-modules of the modular...

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