A Loss Optimal Control Method of Modular Multilevel Converter Under Voltage Unbalance
A modular multi-level, voltage unbalanced technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve the difficulty of increasing the control of modular multi-level converters, Difficulties, increasing the output voltage distortion rate of modular multilevel converters, etc., to achieve the effects of easy construction costs, reduced total loss, and reduced operating costs
Active Publication Date: 2022-08-02
SOUTHEAST UNIV
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[0004] Aiming at the loss optimization control problem of modular multilevel converters, the conventional method optimizes the modular multilevel converter by optimizing the topology of the sub-modules, optimizing the capacitor voltage balance strategy of the sub-modules, or optimizing the modulation strategy of the modular multilevel converter. level converter loss, but the above method has the disadvantages of increasing the control difficulty of the modular multilevel converter and increasing the output voltage distortion rate of the modular multilevel converter, and there are certain difficulties in practical application
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[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0044] Aiming at the loss optimization control problem of the modularized multilevel converter, the present invention proposes a loss optimization control method of the modularized multilevel converter under voltage unbalance. figure 1 , figure 2 As shown, the three-phase MMC is composed of six bridge arms, each bridge arm contains n (n=1, 2, ..., N) submodules (Submodule, SM) with the same topology structure and a bridge arm inducto...
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The invention discloses a loss optimization control method of a modularized multilevel converter under voltage unbalance, comprising: monitoring the current of the upper bridge arm of each phase in real time, the capacitor voltage of each sub-module of the upper bridge arm of each phase and the Sub-module switching device state; use bridge arm current, capacitor voltage and switch state to calculate the loss of each sub-module of the upper bridge arm of each phase; calculate the total loss of the upper bridge arm of each phase; calculate the average value of the total loss of the three-phase upper bridge arm; Calculate the difference between the average total loss of the three-phase upper arm and the total loss of the upper arm of each phase. By changing the carrier frequency of each phase arm, the total loss of the upper arm of each phase is the same, and the modular multi-level converter is achieved. The purpose of loss optimization control. By changing the carrier frequency of each bridge arm, the invention realizes the optimal control of the loss of the modular multi-level converter. Compared with the conventional method, the construction cost of the modular multi-level converter does not need to be increased, and the influence on the output power quality is small and the control algorithm is small. The design is simpler.
Description
technical field [0001] The invention belongs to the field of multilevel power electronic converters, in particular to a loss optimization control method of a modularized multilevel converter under voltage unbalance. Background technique [0002] Modular Multilevel Converter (MMC) is a converter topology in which bridge arms are cascaded by sub-modules. The sine wave method has the advantages of high waveform quality, strong fault handling ability, and low manufacturing difficulty. It has a wide range of applications in medium-voltage occasions such as new energy grid connection and motor drive. [0003] Due to the fact that the voltage on the AC side of the modular multilevel converter is often unbalanced in actual operation, when the modular multilevel converter is in unbalanced operation, the power switches and the sub-modules of the three-phase bridge arm sub-modules are not balanced. The loss generated by the diode will deviate, which will lead to a large difference in ...
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IPC IPC(8): H02M7/5387H02M1/088H02M1/32
CPCH02M7/53871H02M1/088H02M1/32
Inventor 邓富金王梦悦赵纪峰
Owner SOUTHEAST UNIV