Common-mode voltage analysis and suppression in five-level modular composited converter

The common-mode current casued by the parasitic parameters in the transformerless multilevel converters degrades the performance of converters and brings security issues. This paper presents a new zero common-mode voltage space vector modulation for common-mode voltage suppression in the five-level modular composited converter. Firstly, the common-mode equivalent circuit model of five-level modular composited converter is initially derived to further explore its mechanism. Then, a zero common-mode voltage space vector modulation which redistributes the zero common-mode voltage vectors through the flexible coordinate transformation is proposed, and a simpified vector synthesis method is employed to reduce the common-mode current in the five-level modular composited converter. Finally, the effectiveness of the prposed zero common-mode space vector modulation strategy is verfiied by the simulation and experimental results.