Identification of nonlinearities based on comparison of device heating and cooling curves

This paper discusses the problem of nonlinear effects occurring in thermal modelling of electronic systems. In particular, the influence of heat transfer coefficient temperature dependence is studied based on a practical example of free convection cooled power device. The nonlinearity is identified by comparing the recorded heating and cooling curves. Additionally, the analyses are supported also by the presentation of the cumulative thermal structure functions and the time constant spectra.