In Situ Direct Magnetic Loss Measurement With Improved Accuracy for Lossier Magnetics

Abstract

Magnetic loss often tops the power converter’s loss breakdown chart. The optimization of a magnetic component is, therefore, crucial in developing an efficient power converter. However, it is difficult to verify the design of magnetic components <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>in situ</i></b> , while they operate in the desired condition. The accurate, direct magnetic loss measurement is severely hindered by an uncertain timing skew between the measurement channels. This unknown timing skew could introduce an intolerable error in the measured magnetic loss. This article presents a novel method that avails the accurate, direct, and <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>in situ</i></b> magnetic loss measurement. An improved mathematical model of the measured magnetic loss in a power converter is developed with respect to the timing skew. Nonidealities in a practical magnetic component are also incorporated in the model for improved accuracy. The new method termed as triple-curve derivative (TCD) method is introduced and analyzed in detail to determine the actual timing skew and real magnetic loss with an enhanced accuracy, compared to the known methods. The TCD method is validated in simulation and verified in the experiment under various circuit design parameters based on a dc–dc step-down buck converter.