System reliability evaluation considering parameter variations of a single-phase inverter with integrated active power decoupling

Electrolytic Capacitor (E-cap) is one of the lifetime bottlenecks in power electronic converters. In the last two decades, various active power decoupling circuits have been proposed to improve the reliability of the DC link by eliminating the DC-link E-caps. However, additional active devices could change the stresses of the existing converters, whether the system reliability is improving or not is still an open question. This paper investigates the reliability of the single-phase H-bridge inverter with active power decoupling circuit. The parameter variations in IGBT lifetime model are considered. The Weibull distribution of the key components is obtained from Monte Carlo analysis, and the reliability of the whole system is estimated by the system Reliability Block Diagram (RBD) method. As a case study, 2 kW single-phase H-bridge inverter with passive E-caps and active power decoupling circuits are presented. It is shown that the active power decoupling method is applied to H bridge inverter, and the lifetime of decoupling capacitor can be improved significantly, but it has different effects on system reliability in different applications. In addition, the difference on system reliability of fixed parameter and parameter variations is shown in conclusions.