Reliability analysis for a waste heat recovery power electronic interface applied at all-electric aircrafts

Reliability is one of the most important parameters in aircrafts. In this paper, a method for the calculation of reliability (i.e. number of failures / 10⁶ hours) of a three-phase full-bridge inverter, which is employed in the dynamic waste heat recovery system of an aircraft, is presented. The main factors for the reliability analysis that have to be considered is the topology of the inverter, the ambient temperature conditions, the power switches (type and modulation technique), and the harmonic filter. The power inverter reliability has been calculated using a software program developed under the Matlab platform, which was used to calculate the failure rate of each device of the inverter, such as the power switches, the DC-bus capacitor and the filter inductor, given the operating switching frequency value. The results indicate that at higher switching frequency levels the inverter of the DWHR system exhibits a high failure rate, thus resulting in a lower Mean Time Between Failures (MTBF).