DCDC converters are essential in any electric or hybrid vehicle to connect the high-voltage battery to the low-voltage auxiliary circuits. This includes 12 V power headlights, interior lights, wiper and window motors, fans, and at 48 V, pumps, steering drives, lighting systems, electrical heaters, and air conditioning compressors. In addition, the DCDC 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 size was valued at $4 billion in 2023 and is projected to grow to $11 billion by 2030, exhibiting a CAGR of 15% during the forecast period. Gallium nitride (GaN) in particular plays a crucial role here, as it can be used to improve the power density in DCDC converters and on-board chargers (OBC). For this reason, Vitesco Technologies, a leading supplier of modern drive technologies and electrification solutions, has selected GaN to improve the power efficiency of its Gen5+ GaN Air DCDC converter. The CoolGaN™ Transistors 650 V from Infineon Technologies AG significantly improve the overall system performance while minimizing system cost and increasing ease of use. As a result, Vitesco created a new generation of DCDC converters that set new standards in power density (efficiency of over 96%) and sustainability for power grids, power supplies, and OBCs.

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 100 kHz to over 250 kHz. 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 thereby reducing overall system costs. The 650 V devices also improve power efficiency and density, enabling an output of 800 V. In addition, they feature an ON-resistance (R DS(on)) of 50 mΩ, a transient drain-to-source voltage of 850 V, an I DS,max of 30 A, and an I DSmax,pulse of 60 A.

“We are delighted to see industry leaders like Vitesco Technologies using our GaN devices and innovating with their applications,” said Johannes Schoiswohl, senior vice president & general manager, GaN Systems Business Line Head at Infineon. “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.”

With GaN Transistors, Vitesco Technologies was able to design its Gen5+ GaN Air DCDC 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 DCDC 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 3.6 kW and the power density to be increased to over 4.2 kW/l. The Gen5+ GaN Air DCDC converters offer an efficiency of over 96% and improved thermal behavior compared to the Gen5 Liquid-Cooled converters. They provide a two-phase output of 248 A at 14.5 V 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 650 V can be used to implement 800 V 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.