Capacitively coupled transmission line model and validation of a winding-on-core prototype

Broadband circuit models of main components in the drive system are effective means to understand, predict, and control the phenomenon of conducted Electromagnetic Interference (EMI) emissions. These models should cover the capacitive and inductive coupling behavior of the component along the frequency band of interest. Despite the dynamic behavior of EMC-related issues, these circuit models when used under generic SPICE simulation softwares, are very helpful for design-related and troubleshooting activities. In this paper the capacitive coupling for a winding on a laminated Ferro-magnetic core prototype has been investigated and analyzed with the aid of freely available FEMM software package. Capacitive coupling analysis resulted in the generation of complex capacitance network expressing a certain wiring arrangement. This is achieved by automatically generating a netlist file which contains capacitance values and structure to be represented under SPICE simulation software. In the netlist file the turn-to-turn capacitances (Ctt) and turn-to-ground capacitances (Ctg) are calculated from FEMM analysis through a MATLAB® code, employing Lua Scripting Language, and linked back to MATLAB® by a Sparse Matrix Representation in order to control the accuracy and complexity of the resulting network. The capacitive coupling of the winding turns, along with the inductive coupling, will form the resulting SPICE circuit model which is compared against prototype measurements taken by Hewlett Packard (hp) impedance analyzer 4194A.