Analytic Selectivity Evaluation of Vehicular Electronic Fuses' Wire Protection Algorithms

To realize autonomous driving, a fail-operational vehicular power system and proper operation of safety-critical components are necessary. This requires selective triggering of cascaded fuses in case of an excessive current (thermal overload or unexpected current profile). For wire protection, electronic fuses (eFuses) trigger according to an implemented algorithm. Selectivity evaluation is often carried out using the fuse characteristics in the current time diagram. This paper shows that selectivity violations can occur when cascading eFuses with different algorithms and when a dynamic current profile is present, though there is selective behavior according to the static constant current time diagram. This is due to different calculation methods of the algorithms. For this, a methodology is shown for analytic triggering time determination of two easy-to-implement algorithms when a dynamic current profile is present. Furthermore, a comprehensive analysis is done to identify selectivity violations in case of a non-constant current.