New Core Loss Measurement Method for High-Frequency Magnetic Materials

Magnetic core loss is an important concern for power converters. As the switching frequency increases and converter size reduced, the core loss will have significant impact to the converter efficiency and temperature. Accurate evaluation is important for magnetic design and converter loss estimation. The classic two-winding method is limited to low frequencies (usually below 1 MHz) because it is sensitive to phase discrepancy. In this paper, a new method is proposed for high-frequency core loss measurement that utilizes capacitive cancellation, which is suitable for HF and VHF core loss measurement. The new method greatly reduces the sensitivity to phase discrepancy, which is the dominating error source in the conventional two-winding method. An experimental demonstration is performed at 10 MHz, and the possible errors are analyzed in detail. With the proposed method, the high-frequency core loss can be accurately measured.

I. Introduction

Core loss is always an important concern for power electronics applications. The converter is less efficient without proper magnetic cores. With the advance of semiconductors like gallium nitride devices, the power converters have been pushed to higher and higher switching frequencies for the ease of magnetic integration. As the magnetic components get smaller, the core loss will become a limiting factor to converter efficiency and power density. An accurate measurement of the core loss is important to magnetic and thermal design, as well as the exploration of new high-frequency materials. There are several existing methods to test the core loss [1]–[7].