Analysis and Cancellation of Common-Mode Voltage in the Buck Converter

Recent developments in semiconductor technology have led to converter implementations with increased efficiency and power-density. These same developments have also led to increased edge rates that are in part responsible for elevated conducted emissions signatures within such systems. This has recently led to increased treatment for the modeling and mitigation of conducted emissions, with a focus on suppressing common-mode (CM) noise. This paper leverages a generalized decomposition technique to resolve the common-mode equivalent model (CEM) for the buck converter to highlight the elements of most importance to the CM behavior. The developed CEM is then used to identify a targeted cancellation configuration that is predicted to minimize the conducted emissions profile for the buck converter. A custom evaluation platform configured in a conducted emissions setup is leveraged to provide a comparison between a canonical buck converter and the targeted configuration. Significant reduction in the conducted emissions profile is observed across the full frequency regime of interest.