Analysis of SiC technology in two-level and three-level converters for aerospace applications

There is a growing need for highly efficient, power dense DC-AC converters to support a number of future more electric aircraft technologies. SiC has been identified as a potential technology to improve the efficiency of these converters. To analyse the semiconductor losses, this paper presents the semiconductor loss equations for the two-level converter (2LC), three-level neutral point clamped converter (3LNPCC) and the three-level T-Type converter (3LTTC). Based on the equations and current datasheet information, it is identified that SiC technology offers significant reductions in losses compared with traditional Si devices. The paper also discusses a number of hybrid device combinations to achieve the benefits of high efficiency in SiC technology and low cost of Si technology. Based on the semiconductor losses the converter efficiencies in the SiC 2LC and the 3LTTCs are about 3-4 % higher than in the Si 2LC for a 42 kW three phase converter operating at a 25 kHz switching frequency.