Grounding and Common-Mode Characterization

Future naval MVDC power systems will contain a considerable amount of power electronic devices (PEDs). The switching events from these PEDs will cause added harmonic content to the system a produce undesirable effects, such as common-mode (ground) current through coupling of the power system and the ship’s hull. Even in a fully ungrounded ship system, there will exist inherent parasitic coupling. Research in the area of EMI/EMC characterization and standards provides insight into common-mode and conduction currents within a specified component. Yet currently, there is no universal methodology to understand the impacts of these common-mode drivers in the
system context. This report utilizes a common-mode equivalent circuit derivation methodology to begin the discussion and research into common-mode issues at the system-level. Review of the methodology is provided, along with further insight into the definitions and assumptions needed for application. Verification of common-mode voltage characterization is applied to a simulation of an ideal diode rectifier. The methodology is also applied to a representative notional two-zone MVDC simulation case developed within ESRDC.