Key Research Areas

The vehicle's own charger, the On-Board charger (OBC), is the key to universal charging - and therefore a key component for the future of e-mobility. Fraunhofer IZM has now succeeded in combining some of the latest achievements in the field of power electronics for the next generation of on-board chargers. The result: twice the charging power with half the volume, plus bidirectional and machine-manufactured. A cost-effective solution and a signpost for the shortcut to the future.

One system, two innovations: The scientists at Fraunhofer IZM have integrated two key innovations into the new OBC design: the sine-amplitude converter (SAC) and a planar PFC inductor. Both developments are crucial for the compact design, high performance and efficiency of the system. They offer fully machinable and therefore cost-effective manufacturability as well as short cooling paths due to the planar design.

1. Sinus Amplitude Converter (SAC): In the SAC, modern gallium nitride semiconductors (GaN) are used, which enable particularly small and efficient designs due to their high switching frequencies of over 1 MHz. The galvanic isolation of the resonant transformer is crucial in order to reduce low-frequency earth currents and thus ensure safe operation between the grid and the vehicle battery. One of the major challenges during development was to keep losses in the transformer as low as possible through optimized layout and adapted materials.
2. Planar PFC inductor: The planar design of the inductor not only significantly reduces the volume of the OBC, but also enables very short cooling paths. Integration on a PCB base with four magnetically coupled windings on a shared ferrite core also enables cost-effective, automated production in large quantities. The PFC works with silicon carbide (SiC) switches, which allow a switching frequency of 140 kHz and ensure stable operation despite low inductance thanks to the innovative controller hardware and software.

Technical masterpiece in a small format: the new on-board charger design impresses with its compact dimensions of just three liters in volume and yet achieves a charging power of up to 22 kW. Compared to conventional systems, the power density is four times higher. The efficiency is over 97% and the system is compatible with 400 and 800 Volt batteries as well as single and three-phase AC grids worldwide.

Future-oriented bidirectional charging: The new OBC not only makes vehicle charging more efficient, it also provides the ability to discharge. The bidirectional function makes it possible to use the vehicle battery as energy storage for the power grid or your own home - a decisive step towards the energy transition.

Come and visit us! Experience the next-generation on-board charger live at our booth. Let our scientists explain the technical innovations to you and take a look at the sinus amplitude converter, the planar PFC inductor and the entire OBC system.