A Study of CT for Radio-Frequency Currents Using Complex Permeability

This paper describes an analysis of the characteristics of current transformers (CTs), taking the dynamic hysteresis loops of the magnetic core into consideration. The analysis is performed using a complex permeability to represent the magnetic hysteresis. This method is applied to CTs with radio-frequency currents for switching power supplies, and the calculated results are in very good agreement with experiment. This analytical method, which may be used to calculate the ratio of transformation and the CT phase angle, is useful in designing CTs.