Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title Comparative Reliability Analysis of DC-link Capacitor of 3-Level NPC Inverter Considering Mission-Profiles of PV Systems
Authors Jae-Heon Choi ; Ui-Min Choi
Page pp.535-540
ISSN 1229-2214
Keywords NPC inverter; DC-link capacitor; Reliability; PV system; Lifetime
Abstract DC-link capacitors are reliability-critical components in a photovoltaic (PV) inverter. Typically, the lifetime of
a DC-link capacitor is evaluated by considering the voltage and hot-spot temperature of the capacitor under the
specific operating condition of the PV inverter. However, the output of the PV inverter is determined by solar
irradiation and ambient temperature, which vary with the seasons; accordingly, the hot-spot temperature of the
capacitor also changes. Therefore, the mission profile of the PV system should be considered to effectively
evaluate the reliability of the DC-link capacitor. In this study, the reliability of the DC-link capacitor of a
three-level NPC inverter is comparatively analyzed with and without considering the mission profiles of the PV
system, where two mission profiles recorded in Arizona and Iza are considered. The accumulated damage of the
DC-link capacitor is calculated based on the lifetime model by analyzing its thermal loading. Afterward, a
reliability evaluation of the DC-link capacitor is performed at the component level and then at the system level
by considering all capacitors by means of Monte Carlo analysis. Results reveal the importance of performing a
mission-profile-based reliability evaluation during the design of high-reliability PV inverters to achieve the
target reliability performance.