900 V GaN-based sine-wave inverters for three-phase industrial applications

GaN devices are gradually getting attention within the industry along with SiC as a potential wide bandgap device. At present, there are almost no high-voltage GaN devices with voltage >650 V, which makes an inverter design difficult for a three-phase input. To address this challenge to some extent, this study brings in for the first time a full 700 V DC-link-based three-phase inverter-fed high power density system using new 900 V GaN devices. The study also describes how a high switching frequency GaN device can benefit reducing filter size and cost, thereby offering an opportunity to integrate the filter within the inverter. This filter can also provide a sine-wave output compared with the traditional pulse-width modulator output. The article discusses multiple aspects of the design such as (a) switching behaviours of this new device, (b) filters, (c) power losses of the devices within the inverter through comprehensive simulation models and experimental investigations at 128 kHz. Some of the practical challenges are discussed, and the study claims that the GaN inverter for three-phase applications is feasible with this new device.