Three-port nonagonal modular multilevel converter and control method

Abstract

The present invention relates to power electronic converter technology, in particular to the topology and control method of a three-port nonagonal modular multilevel converter. The topology comprises nine groups of bridge arms, and the nine groups of bridge arms are connected end to end to form a nonagonal ring structure. , the nine vertices of the nonagonal ring structure are R, W, X, S, U, Y, T, V, Z in the clockwise direction; where XYZ forms the first port, which is connected to the AC power grid as an input port, RST , UVW form the second port and the third port respectively, which are respectively connected to the first motor and the second motor as output ports. This topology can reduce the number of converters in traditional motor drive systems, and eliminates the need for high-voltage DC bus and phase-shifting transformers, thereby reducing construction and maintenance costs, reducing energy loss, and improving system integration. In order to ensure the stable operation of the dual-machine system, a circulation control method is proposed to realize the flexible energy exchange between the grid and the two motors.

Description

technical field [0001] The invention belongs to the technical field of power electronic converters, in particular to a three-port nonagonal modular multilevel converter and a control method. Background technique [0002] In recent years, with the concept of load driving of medium and high voltage motor groups, it has been proposed and widely studied. As its core technology, the multi-port converter emerges at the historic moment. Through the integration of multiple original discrete converters, the multi-port converter can realize the energy transfer between the power grid and multiple motors, and perform unified management and control of energy, so it has high integration, high efficiency, low volume and Low cost and other advantages. [0003] Traditional multi-port converters usually have multiple two-port converters sharing an AC or DC bus to form a multi-port structure. To a certain extent, the cost is reduced, and the efficiency and integration degree are improved. ...

AI Technical Summary

Problems solved by technology

However, this topology still needs a phase-shifting transformer, and a rectifier is added in front of the single-phase H-bridge inverter in each bridge arm, the devices on the input side are not reduced, and the economic benefits have not been significantly improved

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