Impact of nonlinearities in boundary conditions on device compact thermal models

This paper investigates the influence of nonlinearities in boundary conditions on thermal transients as well as their impact on the values of electronic system compact thermal model elements. The discussions in the paper are based on practical examples where thermal responses of a power device are recorded in various boundary conditions for different values of dissipated power. Then, the measurement results are analyzed using the Network Identification by Deconvolution method and the differences between particular cases are discussed in detail. The presented experimental results clearly show that the nonlinearities due to the temperature dependence of boundary conditions do have important influence on all the values of compact thermal model elements. This might suggest that in some practical cases nonlinear system identification methods should be used.