Wear-out failure prediction of a PV microinverter

Abstract

This chapter assesses and improves the reliability of a photovoltaic (PV) microinverter product by applying two different mission profiles and system-level electrothermal modelling. The system configuration and wear-out analysis process are described in brief before the electrothermal and lifetime models are developed for reliability-critical components in the microinverter, e.g., semiconductor devices and capacitors. Then the mission profiles of two distinct locations, Arizona, USA, and Aalborg, Denmark, are applied to the developed microinverter models, yielding the annual junction hotspot temperature profiles and annually accumulative damages of components. Monte Carlo simulation and Weibull analysis are performed to obtain the system wear-out failure probability. Finally, an advanced multimode control scheme is introduced, and a new long-lifetime electrolytic capacitor is employed in the DC link; leading to a significant reliability improvements of the PV microinverter product.