Soft- and Hard-Switched Performance Evaluation of a Monolithic Bidirectional WBG Device Over a T-Type GaN-Based Circuit

Abstract:
Bidirectional wide band gap (WBG) power devices are realized within different circuitry configurations in power electronics to block a stress voltage in both polarities and to conduct a symmetric current in both directions. While they have been designed as an integral part of many power electronic converters in various applications, their monolithic or discrete WBG-based variants, has a direct impact on both soft-and hard-switching operation. The aim of this paper is to investigate the switching performance of a monolithic bidirectional WBG device integrated into a three-level T-type circuit, which can be operated based on continuous conduction mode, triangular current mode, and also hard-switched inverter mode. Extensive experimental results obtained from a 2 kW laboratory-built prototype using 650 V GaN-Cascode-based FETs are presented at different modulation scenarios. The results showcase the switching waveform of a newly developed monolithic bidirectional device constructed based on two low voltage E-Mode Si devices and a high voltage D-Mode GaN device within a single common-drain package in both soft-and hard-switched-based conditions at 400 V DC-link voltage.