Analysis of Common Mode Voltage using Carrier-based Method for Dual-Inverter open-end winding

Using one DC source for the dual inverter open-end winding topology can lead to common-mode current circulating through the DC bus connections and, to prevent motor failure, arising of EMI issue and increasing losses in the system this should be avoided. Such common-mode current flow results if there is a common-mode voltage (CMV). Therefore, in this paper, a switching scheme for the dual inverter is proposed that eliminates the common-mode voltage by utilizing inverter switching states that should not generate common-mode voltages. These switching states are the middle vectors of the dual-inverter switching table. The middle vectors and the zero voltage vectors, do not generate common-mode voltage. The proposed approach is implemented using a simple carrier-based method. The method is demonstrated using MATLAB/Simulink and experimental results and is compared with the standard modulation scheme. Results demonstrate the improvements but also highlight that, in real applications, dead-time causes unwanted common-mode voltage generation.