Analytical and Experimental Validation Common Mode Feedback Loop for a Three-Phase/Level Vienna Rectifier

The EMI filter can be separated into common mode filter (CM) and differential mode filter (DM). In Vienna rectifier, it is very frequent to place a capacitor that connects the star-point formed by the DM capacitors with the midpoint of the DC-link. This capacitor is known as the feedback capacitor. In this paper the effect of the feedback capacitor on the common mode current is studied when the feedback capacitor is connected to different points of the rectifier. As a result of the study, a mathematical model is obtained, and it is validated on a 1 kW Vienna rectifier prototype.