Direct in-situ Measurement of Magnetic Loss in Power Electronic Circuits

Timing skew between measurement channels can introduce an unacceptable error in power loss measurement and is difficult to quantify, rendering precise in-situ measurement of magnetic loss essentially unattainable. This article rams the issue head-on by presenting the mathematical model for the timing skew and developing two methods based on the model to realize in-situ direct magnetic loss measurement. The mathematical model is first established to analyze the effects of timing skew on the measured magnetic loss in a dc-dc converter. The first method, called intersection method, illustrates how to unravel the entangled relationship between the actual timing skew and real magnetic loss in the circuit with the aid of the mathematical model. The second method, called derivative method, builds on the intersection method and greatly enhances the accuracy and the repeatability of the loss measurement. Our novel approach for in-situ magnetic loss measurement is verified in simulation and experiment with a conventional dc-dc step-down buck converter under various operating conditions and design parameters.