BJT DC–DC converter Dual-Phase-Lag heat transfer model Finite Difference Method scheme Grünwald–Letnikov fractional derivative History of engineering & technology IGBT Krylov subspace-based model order reduction SPICE algorithm convergence analysis algorithm efficiency analysis averaged model compact thermal models computational complexity analysis device thermal coupling diode–transistor switch electrothermal (ET) simulation electrothermal model ferromagnetic cores finite difference method scheme finite-element method (FEM) inductors microprocessor model-order reduction (MOR) modelling multi-LED lighting modules multicellular power MOSFET power electronics relative error analysis self-heating