Measurement Method for High-Frequency Properties of Magnetic Material Used in Power Electronics

This study presents a measurement method for obtaining accurate high-frequency magnetic properties of magnetic materials used as inductor and transformer cores in power electronics circuits. At high frequencies, such as in the MHz range, stray capacitances become significant between lead wires or between the lead wires and the magnetic core. These stray capacitances introduce errors into the measurement results and hinder the accurate determination of magnetic properties. This phenomenon is revealed through numerical calculations that quantitatively combined electric and magnetic field analyses. The results indicate that the conventional measurement method using a toroidal winding core exhibits high stray capacitance. To address this issue, a new method is proposed in which the lead wire passes through the center of the magnetic core without winding, thereby reducing stray capacitance. The effectiveness of this method is demonstrated through the presented analysis.