Analysis of Lifetime Estimation on the DC-Link Capacitor in Three-Level Hybrid ANPC Inverters Under Fault-Tolerance Control

DC-link capacitor loss with fault-tolerance control in three-level hybrid active neutral point clamped (ANPC) inverters was analyzed in this paper. The three-level hybrid ANPC inverter consisted of 18 switch devices such as silicon insulated-gate bipolar transistors and silicon carbide metal-oxide-semiconductor field effect transistors. The numerous switch devices increased the percentage of switch failures. Switch failure distorted the output current and led to the loss of the DC-link capacitor. The loss is related to the shortened lifetime of the DC-link capacitor. To improve system performance and reliability, fault-tolerance control has been studied. However, fault-tolerance control leads to greater loss of DC-link capacitors because of the high voltage ripples, and secondary system failures can occur. In this paper, DC-link capacitor losses are analyzed with fault-tolerance control in a hybrid ANPC inverter and the expected lifetime of DC-link capacitor was determined according to the fault-tolerance conditions. The validity of the analysis was demonstrated by simulation and experimental results.