Design for Reliability of DC-Link Capacitors for Multilevel Inverter Topologies Operating in Hostile Environments

Especially in the mining industry, Pulse Width Modulated Voltage Source Converters (PWM-VSC) are commonly used to drive induction motors at long distances from the inverter. However, this can cause unwanted high-frequency phenomena due to the long cables used for the converter-to-motor connection. A new configuration has been proposed to address this issue, keeping the rectifier in its original location while installing the inverter bridge close to the motor terminals. However, this new configuration can compromise the inverter's lifetime in hostile environments. This paper presents a study on the reliability of DC-Link capacitors for Three Level Neutral Point Clamped (3L-NPC), Three Level Active Neutral Point Clamped (3L-ANPC), and Five Level H-Bridge Neutral Point Clamped (5L-HNPC) inverter topologies in these environments, using methodologies based on Physics of Failure (PoF) and Design for Reliability (DfR).