Investigation on Steady-State and Transient Boundary Condition Scenarios for Optimizing the Creation of Multiport Surrogate Thermal Models

Board-level simulation has to consider, at the earliest stage of the conception, the impact of the vicinity of numerous high- and medium-powered devices. In 1996, the European consortium DELPHI defined the concept of a surrogate, or compact thermal model (CTM), to minimize the computation times from days to minutes. A DELPHI-style CTM resumes an electronic component as a simple cuboid form and a network of resistors that links a single temperature-sensitive node to the major surfaces of heat extraction. That steady-state network is derived from a detailed numerical model, which is subjected to a set of boundary conditions (BCs) applied on its external surfaces. At first, this paper investigates the combinations of various sets of scenarios to generate and to test a multiport surrogate model. The objective is to define the lowest number of numerical simulations required while keeping the highest accuracy level of the derived BC-independent (BCI) thermal network. Then, this paper demonstrates the need of a smart selection of the isothermal surfaces to create a most relevant surrogate model. Finally, using that calibrated steady-state model, an extension of the DELPHI method to create multiport dynamic surrogate model is proposed as well as a set of BCs dedicated to transient network fitting.