Frequency and Temperature Dependence of the Electrical Resistivity of High Frequency MnZn Ferrites

Abstract:
Losses in the ferrite core must be handled carefully when shrinking the size of transformers and inductors in power electronic systems by increasing the switching frequency. This entails calculating the eddy current losses in the core with sufficient accuracy, which is however usually not possible since the electrical resistivity of commercially available ferrites is only roughly known, either from data sheets or other publications. This paper provides a method to determine the frequency and temperature dependent electrical resistivity of the MnZn ferrites Fi329 and Fi337 with sufficient accuracy.