Active Suppression Technology of Common-Mode Electromagnetic Interference in Three-Phase Two-Level Inverter Based on Four-Bridge Topology

This paper focus on the common mode (CM) electromagnetic interference (EMI) problem of three-phase two-level inverter. Firstly, the three-phase four-leg topology is analyzed. The analysis results point out that the output filter midpoint voltage can be used as the observation point of CM voltage. Then the actual suppression effect of CM voltage can be observed. Furthermore, an active suppression technology based on three-phase four-leg topology is proposed. The action delay of the semiconductor is analyzed by statistical method. It is pointed out that the action delay of the semiconductors is not related to the DC side voltage and the magnitude of the current flowing through the semiconductor, but only related to the direction of the current flowing through the semiconductor. Then, an optimization modulation algorithm for compensating the action delay of the semiconductor is proposed, which effectively improves the compensation effect of the fourth leg.