Analytical Modeling of a Gapless Ferromagnetic Core Reactor

This article discusses a novel type of power device, a gapless ferromagnetic core reactor, and its magnetic equivalent circuit (MEC). The developed MEC model is derived from the material and geometrical properties of the device. It is parameterized to take into account the variation in the characteristic design variable, the distance between two similar coils that constitute a winding along the same core leg. The MEC model is quite complex because of the use of more inclusive flux paths in calculating the individual reluctances, which is required to achieve the desired accuracy. Despite the increased complexity, the model can be reduced to a simple form using circuit transformations. The validation of the model is performed by comparing the calculated equivalent inductances of the device with the values obtained from a 3-D finite-element analysis model. The comparison confirms the validity of the developed model within a narrow tolerance. A generic expression for the inductance of the reactor in terms of the characteristic design variable is derived and verified using the developed MEC model.