Investigating Impact of Emerging Medium-Voltage SiC MOSFETs on Medium-Voltage High-Power Industrial Motor Drives

The SiC MOSFETs are becoming game-changing devices in the field of power electronics, enabling higher temperatures, power densities, and efficiencies. However, at higher voltages than 1.7 kV, these semiconductors are at early stages of development and yet not commercialized. Based on the characterization results of the state-of-the-art 3.3-kV SiC MOSFETs, for the first time, this paper investigates the design and comparison of topologies commercially used for medium-voltage (MV) drives in 4.16-13.8-kV voltage range in the presence of MV SiC MOSFETs. For this purpose, the cascaded H-bridge, modular multilevel converter, and five-level active neutral point clamped (5-L ANPC) topologies are targeted. Design is carried out at 4.16-, 6.9-, and 13.8-kV voltages (4.16 and 6.9 kV in the case of 5-L ANPC) and 3- and 5-MVA power ratings using commercial Si IGBTs as well as latest generation noncommercial 3.3-kV SiC MOSFETs, in order to enable investigation of impact from the emerging MV SiC MOSFETs on motor drive system. Selection of several voltage and power levels is to elucidate behavior of converters at a different voltage and power rating and determine the best option for given operating point. Based on design data, comparisons are done among the mentioned topologies from different points of view including efficiency, passive component requirement, semiconductor utilization, power density, low-speed operation capability, fault containment, and parts count. Experimental results on an H-bridge cell made with 3.3-kV SiC MOSFETs are brought to verify converter modeling in MATLAB environment as well as the conveyed thermal calculations.