An Analytical Stray Capacitance Model of NiZn Inductors With Gapped Cores

NiZn cores are widely used in magnetic components in power electronic converters at frequencies above MHz, and the parasitic capacitance generated by air gaps in the cores of inductors can contribute to current ringing and electromagnetic interference (EMI) issues, which cannot be ignored during inductor modeling and design. Current research on air gap capacitance mainly focuses on MnZn materials and can cause significant errors when applied for NiZn materials. In this paper, two models for stray capacitance of air gaps in NiZn cores are proposed. The boundary potential condition is derived by two methods to calculate the electric field distribution and energy capacitance stored in the air gaps. The model can calculate air gaps with different positions, numbers, sizes and boundary conditions. Simulation and experimental verifications are carried out in six cases of gapped core inductors, and the average error of the air gap capacitance is approximately 13.2%.