Implementation of a Nonlinear Planar Magnetics Model

A nonlinear lumped element model for planar magnetics is presented. This technique develops an equivalent circuit model for multilayer planar magnetic components using 1-D analysis of Maxwell's equations. Conducting layers are represented as impedance networks, while the insulating regions are modeled as air-cored inductors. The equivalent circuit model is extended by representing the nonlinear magnetic core material as a nonlinear impedance whose magnetization characteristic is based on the Jiles-Atherton hysteresis model as well as modeling skin and proximity effects in the conductors and current distribution across windings, the improved model also integrates hysteresis loss of the magnetic core and saturation effects. The technique can be implemented in circuit simulation software. A prototype planar transformer, using printed circuit boards to mount windings, was characterized to validate the performance of the model. It is demonstrated that the developed nonlinear model more accurately represents the characteristics of the experimental transformer compared to the existing linear lumped element model. This includes the effect of core saturation on the input current and output-voltage waveforms. The technique is generalized and can be applied to many topologies and geometries.