3-Level power converter with high-voltage SiC-PiN diode and hard-gate-driving of IEGT for future high-voltage power conversion systems

Reductions in the size and weight of medium-voltage power converters are essential for saving space of power conversion systems and cutting their cost. Volumes of magnetic components such as transformers and LC filters are significant in medium-voltage power converters. High-switching-frequency operation is essential for reducing the volume of magnetic components. In this work, hybrid pairs of 6 kV SiC-PiN diodes and 4.5 kV Si-IEGTs have been applied to realize the high-switching-frequency operation of medium-voltage power converters. For low switching losses and series operation of power devices, a gate-driving technique with an extremely low gate resistance called hard gate driving is employed. Switching characteristics of the hybrid pair are measured experimentally. It has been demonstrated that the total switching loss can be reduced up to 50% with the hybrid pair. In order to demonstrate a 2 kHz switching frequency operation of the hybrid pair, which is about 4 times higher than that of conventional medium-voltage power converters, a 378 kVA prototype 3-level inverter has been designed and constructed.