Three-dimensional space vector modulation for four-legvoltage-source converters

摘要

Four-leg voltage-source converters can effectively provide thenneutral connection in three-phase four-wire systems. They can be used inninverter, rectifier, and active filter applications to handle thenneutral current caused by the unbalanced and/or nonlinear load ornunbalanced source. In this paper, three-dimensional (3-D) space vectornmodulation (SVM) schemes are proposed for controlling the four-legnvoltage-source converters. Important issues for 3-D SVM, such asndefinition of 3-D vectors, identification of adjacent switching vectorsnin the 3-D space, and switching vector sequencing schemes andncomparisons are addressed. The proposed 3-D SVM is a superset of thentraditional two-dimensional (2-D) SVM, and thus it inherits all thenmerits of the traditional 2-D SVM. A 100 kW 5 kHz four-leg inverter andna 20 kHz four-leg rectifier prototypes are built and controlled by thenproposed 3-D SVM. Experimental results are presented to validate theneffectiveness of the 3-D SVM