In-situ Direct Magnetic Loss Measurement in a DC-DC Converter

It is a challenging task to accurately measure power loss of an inductor in-situ in a DC-DC power converter, mainly due to measurement difficulties, e.g., channel timing skews in an oscilloscope and additionally introduced measurement parasitics. In an effort to avoid such difficulties, one of the work-around approaches is usually taken: estimating inductor loss by deducting all loss mechanisms from input power; calorimeter; or testing an inductor in an independent platform to extract parameters for Steinmetz equation or one of its many variations. However, these methods have well-known shortcomings, e.g., necessity of precise modeling on all components except for the inductor, limited validity of parameters in a design space, etc. In this paper, an in-situ direct measurement of inductor loss is explored. The most demanding challenge in in-situ power loss measurement – timing skew between measurement channels – is analyzed for a typical DC-DC converter, and a novel method to generate precise loss measurement under the presence of timing skew is proposed.