Investigation on the Pathway of Common Mode Current in Electrical Machine Stator Core Laminations

This study investigates the common mode current path in voltage source inverter-fed electrical machine systems, focusing on its distribution within stator laminations and the outer frame. Via finite element analysis and experimental validation, it challenges the notion that the common mode current mainly follows a zigzag pathway along the inner surface of stator laminations in inverter-fed machines. The findings reveal that while part of current flows through the laminations, the majority flows through the frame outer surface, influenced by the skin effect. These results underscore the importance of understanding the common mode current pathway for better estimation and mitigation of the shaft voltage and bearing currents in inverter-fed machines.