Power loss measurement system for soft magnetic materials in megahertz frequencies

Soft magnetic materials play a key role in developing integrated and miniaturized power electronics. However, it is still challenging to accurately evaluate the high-frequency (MHz) power loss of soft magnetic materials, which determines the energy efficiency of power electronics. In this paper, we firstly trace the high-frequency error origination in traditional electrometric method and propose a two-step calibration method for the system to compensate the phase angle discrepancy between exciting current and induced voltage. The first-step calibration eliminates the phase angle discrepancies caused by propagation delay of current and voltage probes, while the second-step calibration compensates residual phase angle discrepancies. A calibration factor k is defined to determine whether the second-step calibration is needed. The experimental results demonstrate that the system's phase discrepancy is compensated within 0.13 degrees, enabling power loss measurement frequency up to 20 MHz that much higher than present apparatus. Our results will facilitate the development of high-frequency soft magnetic materials and promote the miniaturization of power electronics.