Introduction

The rapid technological expansion means that the appetite for power is increasing. In order to fuel this expansion sustainably, renewable energy sources such as solar are being deployed to power grids increasingly. Similarly, the need for servers is increasing exponentially to enable faster data processing, big data storage and artificial intelligence (AI). As a result of worldwide trends, designers have a big task at hand: keep increasing efficiency in their designs while delivering more power in the same footprint.

This challenge has already pushed the adoption of gallium nitride (GaN) in high-voltage power designs because GaN has two major advantages:

• Increased power density. GaN’s higher switching frequencies enable designers to use smaller-sized passives such as inductors and capacitors, thereby reducing board dimensions.
• Increased efficiency. Compared to silicon designs, GaN’s superior switching and conduction-loss performance reduce losses by >50%.

Alongside the industry-adopted high voltage GaN (rated >=600V), new mid-voltage GaN solutions (rated 80V-200V) are becoming increasingly popular to achieve higher power density and efficiency in power systems that high voltage GaN previously could not support.

In this article, I’ll describe four major mid-voltage application areas where the adoption of GaN is spreading.

Application No. 1: Solar energy

Solar energy is the fastest-growing source of renewable energy, rising 26% from 2021 to 2022 with a projection to expand capacity at a compound annual growth rate of approximately 11.5% in the next seven to eight years. As solar panel installations increase, so will the need for system efficiency and power density, as it is a space-intensive technology. For solar panel subsystems, the LMG2100R044 and LMG3100R017 devices can help reduce system size by over 40%.

Solar power is enabled primarily by two types of subsystems at the solar panel: a boost stage followed by an inverter stage to convert a DC voltage range to an AC voltage (see Figure 1), and a buck and boost stage in which a power optimizer converts a varying DC voltage to a common DC voltage level (using maximum power-point tracking) for delivery to a string inverter (see Figure 2).

Application No. 4: Motor drives

Yes, you can use GaN in motor-drive circuitry. The applications are diverse, and include robotics, power tool drives and two-wheeled traction inverter designs, with different load profiles. GaN’s zero reverse recovery (because there is no body diode) leads to no settling time for the current in reverse bias of the diode, which causes lower dead-time losses and better efficiency. As a result of GaN’s higher switching frequencies, there is lower current ripple, which as I mentioned earlier enables a reduction in the size of passive components, and can lead to sleeker motor-drive designs.

Figure 4 depicts how GaN can fit into motor drives.

Conclusion

GaN has the potential to replace traditional silicon FETs in mid-voltage applications across the board. Other application areas for 100V to 200V GaN include general-purpose DC/DC conversion, Class-D audio amplifiers, and battery test and formation equipment. GaN also offers higher switching frequencies and lower power losses, benefits that become more pronounced with integrated power stages that simplify power designs.