Impact of Open-Switch Fault in Five-Phase Three-Level NPC Inverters

In recent years, interest in multiphase converters has increased due to the growing attention paid to the efficiency and reliability of electric drives. Additionally, multilevel converters have become a more mature technology and are a suitable solution for achieving high power levels from devices with limited voltage ratings. Multiphase-multilevel converters combine the advantages of both technologies to provide high-power and high-reliability converters. Since the multiphase system is inherently fault-tolerant, a dedicated control technique needs to be developed. This paper presents a fault-tolerant strategy for a five-phase three-level T-type converter that exploits the degrees of freedom provided by multiphase technology to reduce the negative effect of an Open Switch Fault and minimize the voltage ripple across the DC-bus capacitors in each switching period and during the fault.