Improved Short-Circuit Capability with "Si+SiC" Hybrid 5-Level Active NPC Converter for Electric Aircraft Propulsion

Moving toward electric propulsion drives in aircraft applications is a significant step forward to enhance the efficiency of aviation systems. Taking advantage of medium voltage DC (MVDC) as a leading edge technology can further increase the efficiency and power density. To this end, emerging wide-bandgap devices with lower switching losses can be incorporated into multilevel inverter topologies. However, existing Silicon Carbide (SiC) switches have weak short-circuit capability. This is the main downside of all-SiC inverter topologies which restrains their application in safety-critical applications. On the other hand, Silicon (Si) IGBTs have better short-circuit performance, although rendering higher switching losses. To overcome this challenge, a hybrid "Si+SiC" five-level active neutral point clamped (ANPC) inverter is proposed in this paper to improve the short-circuit capability of the aircraft propulsion drive systems. Simulation results comparing the efficiency and short-circuit capability of all-SiC, all-IGBT, and hybrid "Si+SiC" topologies are presented to demonstrate the effectiveness of the proposed topology.