Abstract
Accurate loss analysis of switch mode circuits that use IGBTs as a switching device is difficult. Switching losses are a function of switch current, collector voltage and junction temperature. These three-dimensional parameters increase equation complexity and are often time consuming in their determination. However, computer programs such as MathcadTM MatlabTM ExcelTM and Table CurveTM provide practical means of curve fitting empirical data. This paper outlines a methodology for recording and converting empirical IGBT performance data into accurate and useful equations. These equations may then be utilized as simple function calls for loss analysis calculations. The examples covered in this paper are the IGBT clamped inductive turn-off energy and VCE(SAT) on-state drop. The losses predicted by the empirical equations are compared with in-circuit measured losses. IGBTs representing two different technologies are modeled.
