Concerns have been raised that motor voltages might be very high if the fast switching characteristics of silicon carbide (SiC) are to be utilized. For this reason, the magnitude of the terminal voltage of an induction motor is investigated when fed from a fast switching SiC inverter through a long cable. It is found that the main insulation demand for the SiC case is only increased by 5 % compared to the silicon insulated-gate bipolar transistor (IGBT) case. This indicates that additional filters may not be necessary in applications with long cables where silicon IGBTs are replaced by fast switching SiC power semiconductors.

For the first time results are reported in literature of a successful field test using a silicon carbide (SiC) metal-oxide semi-conductor field-effect transistor (MOSFET) traction inverter operated in the field. The metro train has been operated over a period of 3 months on the Green Line in the Stockholm metro system. Increased traction converter power density with a volume reduction of 51 % as well as a weight reduction of 22 % have been achieved. Lower power losses allow the use of car motion cooling. From complementing measurements in the laboratory of silicon and SiC in the same power device package with varying switching frequencies considerably lower SiC temperatures can be reported.