GaN Based Designs For Compact Low-Voltage Power Converters

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Researchers at the Fraunhofer Institute IAF have presented interleaved GaN transistors design for improved efficiency.

In automotive and other power converters, Gallium Nitride (GaN) based power transistors can increase the performance due to wide bandgap and offer the best compromise between safety, compactness and efficiency. Various applications such as e-bikes, robotics or drones, drive and board systems in mobility, or IT infrastructures—all these sectors rely on cost-effective, efficient and compact electronics. GaN based power transistors offer high energy density, high voltage operation, cost-effectiveness, and much more compactness as compared to their silicon counterparts.

The scientists at the Fraunhofer Institute of Applied Solid State Physics IAF have presented pioneering integration concepts with GaN-based integrated circuits (ICs) for low-voltage applications. The scientists are researching GaN-based circuits for power electronics applications, even at low voltages of up to 48V.

The 48V class has become an industry standard for modern energy efficiency power converters. This is due to the more efficient power transmission it offers compared to lower supply voltages. According to the researchers, 48V offers an ideal compromise between efficiency and safety. Furthermore, there is no need for elaborate safety measures, which renders the voltage class suitable for everyday applications.

The researchers present GaN based components and systems ideal for 48V technology. They presented their research at the international conference for power electronics, intelligent drive technology, renewable energies and energy management PCIM 2021.

The researchers demonstrated how they interleaved two two transistors of an integrated half-bridge for a highly compact design, instead of the usual side-by-side integration. This approach increases the area-efficiency. They furthermore integrated three such half-bridges into a motor inverter GaN IC for low-voltage applications, and realized an advanced packaging technique for GaN ICs.

“GaN technology allows the integration of a half-bridge consisting of two power transistors in one chip, which significantly increases the compactness of a system. In order to take advantage of this, however, it is extremely important to optimize the integration at the packaging and chip level,” explains Michael Basler, a Ph.D. student at Fraunhofer IAF.

Commercial GaN based half-bridge ICs integrate two power transistors in one chip, but only side-by-side, which does not utilize the full potential of these devices. The interleaved version developed by the researchers improves efficiency significantly. Stefan Mönch of Fraunhofer IAF, explains, “The intrinsic half-bridge improves the electrical switching properties, and all three phases in the same IC reduce the temperature swing during motor operation. Only one IC is also more cost-efficient and easier to build than six transistors or three half-bridges previously needed for a GaN-based motor inverter.”


 

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