Fraunhofer IZM, a leading German research institute, has introduced a revolutionary onboard charger technology that promises to transform electric vehicle charging. The institute’s latest innovation offers twice the charging power at half the volume of conventional chargers, marking a significant advancement in power electronics for the next generation of onboard chargers.
One of the key achievements of Fraunhofer IZM is the development of an onboard charger that significantly reduces the volume of such devices to just three litres, a remarkable feat compared to traditional chargers. This reduction in size is coupled with a doubling of the charging power from 11 to 22 kW, enabling rapid charging capabilities while maintaining a compact form factor.
The new module is compatible with both 400 and 800-volt batteries, boasting an impressive efficiency of over 97 percent. What sets this technology apart is its bidirectional charging capability, allowing the car’s battery to not only charge from the grid or home power but also contribute power back to the home or grid, a concept known as vehicle-to-grid (V2G) charging.
To achieve this groundbreaking innovation, Fraunhofer IZM developed several key components that were integrated into a small space. One of these components is a sine-amplitude converter (SAC), a high-frequency transformer that ensures galvanic isolation of the vehicle battery from the supply grid. The use of gallium nitride semiconductors (GaN) in the SAC allows for switching the transformer on and off at a clock frequency of 1.3 MHz, enabling a total redesign of the module.
Another critical component is the power factor correction converter (PFC), which stabilizes the AC voltage from the supply network. Fraunhofer IZM has developed a flat PFC choke based on a printed circuit board, significantly reducing the size and cost of this component.
Oleg Zeiter from Fraunhofer IZM emphasized the impact of these innovations, stating, “These high frequencies mean that we can totally rethink how we design the module.” He further explained, “Because we only ever switch on the current for an extremely brief moment in time, it never reaches high amperage, even at low inductivity – all thanks to the quick switching.”
This new onboard charger represents a significant advancement in electric vehicle charging technology, offering a more efficient, compact, and cost-effective solution. The device will be showcased at the Fraunhofer IZM stand (Hall 5, Stand 300) at PCIM Europe, an international trade fair for power electronics, held in Nuremberg, Germany, from June 11 to 13, 2024.
