Fraunhofer Institute for Reliability and Microintegration IZMPCB and packaging solution for on-board chargers — On-board charger in three liters - packaging makes it possible
Charging on public AC grids is a challenge for e-mobility. Fraunhofer IZM has now succeeded in combining the latest achievements in the field of power electronics for the next generation of on-board chargers. Bidirectional charging processes of up to 22 kW are made possible by pioneering PCB and packaging solutions that also enable automated production.
The SIIT department at Fraunhofer IZM has succeeded in taking the design of an electric car's on-board charger (OBC) to the next level of development. One of the two key newly developed components is the sine-amplitude converter (SAC), which utilizes innovative wide-bandgap semiconductors based on gallium nitride (GaN). The new GaN switches make it possible to clock the resonant transformer - with an LLC topology - at 1 MHz and higher.
The other of the two essential components is the power factor correction converter (PFC) - a bulky component with high production costs in previous OBCs, particularly due to the chokes required. At Fraunhofer IZM, planar PFC chokes have been developed on a PCB basis, with four magnetically coupled windings on a common ferrite core. The flat design not only saves space, but is also associated with very short cooling paths. Although this means low inductances, a higher clock frequency also helps here: the PFC is constructed with silicon carbide switches (SiC) and can therefore be clocked at 140 kHz.
The combination of these and other components enables a future-orientated OBC with excellent properties:
- Space requirement of just three liters
- Low production costs because it can be manufactured by machine
- Compatible with 1-phase and 3-phase AC grids of different voltages up to 22 kW
- High efficiency of 97
- Adaptable for 400 and 800 V batteries
- bidirectional charging (car battery can be used as energy storage)