Design and Qualification of a 100-kW Three-Phase SiC-Based Generator Rectifier Unit Rated for 50 000-Ft Altitude

Featuring higher blocking voltage, smaller parasitic elements, faster-switching speed, and a more compact package, wide bandgap (WBG) semiconductor devices like silicon carbide devices (SiC), can enable compact aircraft generator-rectifier units (GRUs) thus making them highly desirable. Yet, the combination of the increased voltages, high-power density, and the lower pressure environment associated with aircrafts can pose a significant threat to the converter operation due to the increased sensitivity to electric field (
$E$
-field) intensity inside the GRU components and their assembly. To this end, a comprehensive design and qualification of a 100-kW three-phase SiC-based GRU rated for a flight altitude of 50000 ft (11.6 kPa) is presented in this article. First, an insulation coordination based on Paschen-curve is proposed to improve the power density. High
$E$
-field areas of the GRU are determined and preemptively solved with the use of an
$E$
-field control methodology to prevent partial discharge (PD) under normal operating conditions. Second, the gate driver and electromagnetic interference (EMI) filter components are optimized for operation at 70 kHz. Finally, the insulation design is qualified through low-pressure PD tests, and it is verified that the unit successfully operates at rated conditions to achieve 33.3-kW/l power density, 99.2% efficiency, and PD-free operation at 50000 ft.