Monte Carlo Based Reliability Estimation Methods in Power Electronics

In mission-profile based reliability assessments, it is a common method to calculate the static parameters that represent the thermal stress of power electronic converters. These parameters are afterwards used in Monte Carlo (MC) simulations for estimating the expected lifetime of the components in power converters taking into account variations. However, the static parameters do not always represent the real field operating conditions of the components in power converters. To overcome this limitation, two approaches to introduce a parameter variance are implemented in the dynamic mission profile characteristics used in MC simulations in this paper. In two different application cases, it is demonstrated that using static parameters can introduce a significant error in the MC simulation. For the photovoltaic (PV) inverter applications the lifetime of a semiconductor can be overestimated up to 30% if the static parameters are used, while for uninterrupted power supply (UPS) system applications this difference can reach almost 50%.