The power converter is a little-known system that allows us to plug in computers, lights, and televisions and turn them on in an instant. The converter converts alternating current (AC) from a wall socket into direct current (DC) required by electronic products. But in the process, they also lose an average of up to 20% of their energy.
The working principle of power converters is to use power transistors. These tiny semiconductor components can be designed to switch power supplies and can withstand high voltages. Recently, researchers at the Federal Institute of Technology in Lausanne (EPFL) in Switzerland have designed a new power transistor that can help improve the efficiency of the converter.
It is reported that their new design is based on a nanoscale structure, which loses much less heat during the conversion process, making this transistor particularly suitable for high-power applications such as electric vehicles and solar panels. The research results were also recently published in the well-known scientific journal "Nature Electronics".
The heat dissipation of the inverter is mainly caused by factors such as high resistance, which is the biggest challenge faced by power electronic equipment. Elison Matioli, the co-author of the paper and the head of POWERlab at EPFL, said, “We can see examples of power loss every day, such as the heating of laptop chargers. In high-power applications, this will become a bigger problem.”
"The higher the nominal voltage of the semiconductor component, the greater the resistance. For example, power loss will shorten the mileage of electric vehicles and reduce the efficiency of renewable energy systems." He added.
Matioli and his PhD student Luca Nela and their team have developed a transistor that can greatly reduce the resistance and heat dissipation of high-power systems. More specifically, its resistance is less than half of traditional transistors, but the voltage can be maintained above 1000V.
Specifically, EPFL technology contains two key innovations. The first is to establish several conductive channels in the component to distribute current-just like adding new lanes on a highway, to make traffic smoother and prevent traffic jams. Nela pointed out, "Our multi-channel design splits the flow of current, reducing resistance and overheating."
The second innovation is the use of nanowires made of gallium nitride, which is an ideal semiconductor material for power applications. Nanowires have been used in low-power chips, such as smart phones and notebook computers, rather than high-voltage applications. POWERlab demonstrated nanowires with a diameter of 15 nanometers and a unique funnel-like structure that enables them to support high electric fields and voltages exceeding 1000 volts without being broken down.
Thanks to the combination of these two innovations: a multi-channel design that allows more electrons to flow, and a funnel structure that enhances the resistance of the nanowires, transistors can provide higher conversion efficiency in high-power systems. Matioli said, "The performance of the prototype we built using tilted nanowires is twice that of the best GaN power devices currently."
Although the engineers' technology is still in the experimental stage, there should not be any major obstacles to mass production. Matioli said, "Adding more channels is a very simple matter, and the diameter of our nanowires is twice the size of small transistors made by Intel."
With the wider application of electric vehicles, the demand for chips that can operate efficiently at high voltages will surge, because more efficient chips can be directly converted into longer cruising range. Some major manufacturers have already expressed interest in cooperating with Matioli to further develop this technology.