Design and Characterization of Bus Bars for 1-MVA Three-Level ANPC Inverters in Aerospace Applications

Bus bars play a crucial role in connecting components and are widely utilized in high-power inverters. Efforts have been made in the past to reduce the stray inductance of bus bars. In the case of multilevel inverters, which involve more complex commutation loops than their two-level counterparts, the physical layout and parasitic parameters of bus bars are particularly important. Furthermore, for novel and more demanding applications such as aerospace, bus bars need to be designed to be lightweight while ensuring a partial discharge (PD)-free insulation performance. Given the challenging cooling condition in aerospace applications, the thermal design and cooling performance of bus bars also warrant considerable attention. This article presents a comprehensive design approach of a laminated bus bar for a 1.5-kV 1-MVA three-level active neutral-point-clamped (ANPC) inverter for electrified aircraft propulsion. With the proposed design methodologies, 29.4- and 48.8-nH inductance for short and long commutation loops, PD-free insulation, and satisfactory thermal performance are achieved with an only 1.77-kg layout. Experimental results confirm that the efficiency of the 1-MVA ANPC inverter can reach 98.97% under half-load conditions with the designed bus bar.