A Constant Common-Mode Voltage PWM Method for Three-Phase Series-end Winding Topology

In this paper, a constant common-mode voltage PWM method is proposed for a three-phase series-end winding topology. Compared with the traditional half-bridge topology, the series-end winding topology is able to achieve nearly twice the voltage utilization based on the addition of one bridge leg. However, the existing modulation methods for this topology suffer from large common-mode voltage (CMV) fluctuations. Through analysis, the corresponding relationship between CMV and bridge legs switch states under this topology is obtained. The proposed modulation method is able to limit the common-mode voltage amplitude to 1/3 of the conventional scheme and keep it essentially constant. In addition, under the constant common-mode voltage modulation, the voltage utilization advantage of the series-end winding topology is still maintained compared to the half-bridge topology. The experimental results verify the effectiveness of this method in common-mode suppression.