Serkan Dusmez from Texas Instruments recently recorded a short video with us on a gallium-nitride based grid link. It is a three-phase, three level bidirectional grid tight inverter developed jointly by Texas Instruments and Siemens. It includes 600-V GaN TI drivers that incorporate smart features like over voltage protection and over temperature protection in a single low-conductance package. The integration aids in switching the GaN transistors quickly and with minimum overshoot.

The switching frequency is 150 kHz compared to 20 kHz for the non-GaN version. The higher switching frequency allows the inductor size to shrink by 80% and the power semiconductor footprint area to diminish by 80%. With ordinary IGBTs, the inductors visible in the video might have to be at least five times larger. And the whole footprint of a typical silicon IGBT-based inverter would be about three times larger than the GaN circuit shown here.

In the real world, a GaN inverter design like this one might be used in grid-tied solar inverters which accept the high dc link voltage. Another application is in EV chargers and battery storage systems that accept high voltage.

A thermal camera focused on the GaN parts in the video reveals the temperature stays at 65°C. The cooling is done with two quiet fans and there’s not much of air cooling.