News: Microelectronics
9 August 2024
Vitesco uses Infineon’s CoolGaN transistors to boost power density in DC–DC converters
Infineon Technologies AG of Munich, Germany says that Vitesco Technologies of Regensburg, Germany (which develops and manufactures drive technologies and electrification solutions for electro-mobility) has selected its CoolGaN Transistors 650V to improve the power efficiency of its Gen5+ GaN Air DC–DC converter. The transistors are said to significantly improve the overall system performance while minimizing system cost and increasing ease of use. As a result, Vitesco created a new generation of DC–DC converters that are said to set new standards in power density (efficiency of over 96%) and sustainability for power grids, power supplies, and OBCs.
DC–DC converters are essential in any electric or hybrid vehicle to connect the high-voltage battery to the low-voltage auxiliary circuits. This includes 12V power headlights, interior lights, wiper and window motors, fans and, at 48V, pumps, steering drives, lighting systems, electrical heaters, and air conditioning compressors. In addition, the DC–DC converter is important for developing more affordable and energy-efficient vehicles with an increasing number of low-voltage functions. According to TechInsights, the global automotive DC–DC converter market is increasing at compound annual growth rate (CAGR) of 15% from $4bn in 2023 to $11bn by 2030. Gallium nitride (GaN) in particular plays a crucial role, as it can be used to improve the power density in DC–DC converters and on-board chargers (OBC).
Picture: Infineon’s CoolGaN Transistors 650V.
The advantages of GaN-based transistors in high-frequency switching applications are considerable, but even more important is the high switching speed, which has been increased from 100kHz to over 250kHz. This enables very low switching losses, even in hard-switched half-bridges, with minimized thermal and overall system losses. In addition, Infineon’s CoolGaN Transistors feature high turn-on and turn-off speeds and are housed in a top-cooled TOLT package. They are air-cooled, eliminating the need for liquid cooling and hence reducing overall system costs. The 650V devices also improve power efficiency and density, enabling an output of 800V. In addition, they feature an ON-resistance (RDS(on)) of 50mΩ, a transient drain-to-source voltage of 850V, an IDS,max of 30A, and an IDSmax,pulse of 60A.
“The ultimate value of GaN is demonstrated when it changes paradigms, as in this example of moving from a liquid-cooled system to an air-cooled system,” comments Johannes Schoiswohl, senior VP & general manager, GaN Systems business line head at Infineon.
With GaN Transistors, Vitesco was able to design its Gen5+ GaN Air DC–DC converters with passive cooling, which reduces the system’s overall cost. The GaN devices also allow for simplified converter design and mechanical integration. As a result, the DC–DC converters can be flexibly positioned in the vehicle, reducing the workload for manufacturers. The use of GaN also allows the power of the converters to be scaled up to 3.6kW and the power density to be increased to over 4.2kW/l. The Gen5+ GaN Air DC–DC converters offer an efficiency of over 96% and improved thermal behavior compared with the Gen5 Liquid-Cooled converters. They provide a two-phase output of 248A at 14.5V continuous. The phases can be combined to achieve the maximum output power. Still, it is also possible to switch off one phase under partial load conditions and interleave the switching frequency between the two phases. In addition, by switching the input of two phases in series, the converters based on the CoolGaN power transistors 650V can be used to implement 800V architectures without exceeding the maximum blocking voltage of the device. The converters also feature an isolated half-bridge topology consisting of a GaN-based half-bridge, a fully isolated transformer, and an active rectifier unit for each phase.
