Concept of Inductor with a Virtual Air Gap for Increasing Fault Current Capability in Traction Drive Applications

Energy efficiency is important in many applications including electrical drives. DC powered electrical traction drives require an input filter to limit voltage fluctuations, electromagnetic interference, and fault currents. The losses in the inductor of the input filter can be reduced by applying a magnetic core and by reducing the number of windings. High fault current can lead to saturation of the core thus resulting in substantial inductance reduction. This paper analyzes the possibility of introducing a virtual air gap to limit core saturation and limit fault current. The FEM simulation method is used to analyze the magnetic flux in the core. The results shows that the proposed method can be useful for such applications, but additional control is required to control the current in the electrical circuit that creates a virtual air gap.