Three‐level GaN inverter with SiC diodes for a possible three‐phase high power solution

Abstract

GaN device is a potential alternative to SiC as a wide band gap device. At present, there are almost no high-voltage GaN devices above 650 V, which makes an inverter design difficult for three-phase input using the standard two-level (2L) inverters. Therefore, at present, a three-level (3L) inverter is an obvious choice for the GaN inverter for three-phase 400/480 V input applications. Moreover, a 2L inverter suffers from drawbacks like increased filtering efforts, high dv/dt and limited switching frequency due to the effect of power loss on semiconductors. Therefore, at the medium-to-high-power level, a hard switched GaN inverter with a 2L structure is still questionable. To address some of the challenges, this study brings in a 700 V dc-link-based three-phase, 3L inverter with GaN and SiC diodes. This study discusses multiple aspects of the design such as (a) advantages over the 2L design at a higher power, (b) filters designs, (c) power losses in the devices and (d) design challenges of the inverter through comprehensive simulation models and experimental investigations. The study claims that the GaN inverter for the medium-to-high-power level makes more sense with a 3L design.