Linear unknown input functional observer for thermal estimation in power electronic modules

Abstract

High integrated power electronic modules are more and more designed with the emergence of new semi-conductor technologies. Thus, increase of reliability of power modules induces the precise knowledge of the local temperature, even if it can not be measured at any location. Moreover, some external variables of having an effect on the system may be unknown. In this paper, the application of an unknown input observer is proposed. It allows us to estimate the temperature at any location using measurements provided from thermal sensors located at a few precise points without measuring all inputs of the system. The aim is then to estimate internal temperature of a system in order to prevent over-temperature operations and then fault of the system. Consequently, a linear unknown input functional observer (LUIFO) of minimal order observer is design for thermal estimation of silicone gel used in power electronic modules.