Characterization of Mutual Coupling for dc-biased Controllable Magnetic Devices

Paper i proceeding, 2025

In recent years, controllable magnetic devices gained a major interest in different application areas as they offer another level of freedom to power electronic systems, improving system efficiency, power density and controllability. However, comprehensive physical behavior of variable inductors (VIs) remains poorly studied with respect to controllability and coupling effects between the auxiliary and primary winding. This paper introduces a novel measurement-based characterization method for identifying and quantifying mutual coupling effects in dc-biased magnetic devices. Therefore, two toroidal core structures, an orthogonal (OM) and a mixed-biased (MB) pre-magnetized core, are investigated, highlighting the differences in coupling behavior. The method applies Fast Fourier Transformation (FFT) to induced voltages on the auxiliary winding, enabling the assignment of specific harmonic components to distinct coupling mechanisms. Harmonic-specific coupling factors are proposed to isolate individual effect. Thus, this paper aims to provide a characterization method applicable to any dc-biased magnetic device, helping to isolate coupling effects and quantify magnetic coupling by means of specific factors. A general analytical model will be proposed to interpret the measured coupling effects.