Improved Oscillation Method for High-Frequency Magnetic Core Loss Measurement

Accurate measurement of magnetic core loss is of great significance for magnetic and thermal design for power electronic converters operating at high frequencies. However, the commonly used two-winding method is difficult for ultrahigh frequency measurement due to the voltage and current phase error. The oscillation method presents a promising solution for high-frequency applications, albeit with the drawback of additional switch losses. To address these challenges, this study proposes an improved oscillation method that eliminates the switch on-state loss by removing it from the resonant circuit and reduces the switch off-state loss by a transformer utilizing its impedance amplification effect. This article begins with an analysis of the underlying principle, including the improved oscillation test circuit, procedure, and core loss calculation algorithm. Next, implementation considerations such as the magnetizing coil, test conditions, switch components, and compensation for other losses are discussed. Finally, experimental work is conducted to evaluate the proposed method at 300 kHz, 2 MHz, and 10 MHz. The results validate its superior accuracy at high frequencies while effectively mitigating switch losses to negligible levels.