Key Research Areas

Sine-Amplitude-Converter (SAC) for e-mobility on-board charger

Zeichnung On-Board Charger
© Fraunhofer IZM

As part of the European project "HiEFFICIENT," the use of novel and high-performance semiconductors, known as wide-bandgap semiconductors, is being investigated for the next generation of electric vehicles. The project aims to develop an efficient integrated charging unit for electric vehicles with a power of 22 kW.

For on-board chargers in electric vehicles, galvanic isolation between the power supply network and the vehicle battery is required. By using gallium nitride semiconductors (GaN), switching frequencies in the megahertz range can be achieved, allowing for a reduction in volume through smaller magnetic components. For galvanic isolation and voltage transfer, a Sine-Amplitude-Converter (SAC) is used, which has an LLC topology in terms of circuitry.

To obtain a highly efficient and power density-optimized system, special attention must be paid to a compensated transformer design that is necessary to keep losses low. Due to its low installation height, the transformer was designed with conventional PCB technology. The low profile creates a very short thermal path to the heat sink. PCB technology enables cost-effective and reproducible manufacturing with very high quantities.

A symmetric current distribution within the layers requires special care in the design of the layer structure and the connection of the transformer to the half-bridges and the local DC link. Optimization regarding current displacement effects was carried out using a 3D field simulator.

The result of the optimization was a transformer for a power of 11 kW with a total height of less than 13 mm, achieving a power density of 56 kW/l (without heat sink) with a maximum total efficiency of 98 percent.

This might also be of interest to you


Key Research Areas

Compact converters enabling high power density

Due to the low switching losses when using the novel wide band-gap semiconductor generation made from gallium nitride and silicon carbide, respectively, it is possible to increase the switching frequency of power electronic systems significantly.


Key Research Areas

PFC inductor for an on-board charger used in e-mobility

The conversion of automobiles from conventional combustion engines to electric drives represents an enormous challenge for the automotive industry. In addition to high efficiency and low weight, costs are of particular importance in high unit volumes.


Key Research Areas

FU integration – highly integrated frequency converter

The overall objective of the project is the development of a modular frequency converter to be integrated into electric motors of circulating pumps with significantly reduced volume and weight, increased efficiency, and the reduction of electromagnetic interference.


Key Research Areas

SiCefficient: increase of efficiency and range

The use of SiC semiconductors in drive inverters is becoming increasingly popular. SiC offers the possibility of increasing the power density and efficiency in the system through lower switching and conduction losses compared to silicon FETs.


Key Research Areas

HSHT - High-Speed-Hybrid-Turbo

Power generation from exhaust gas to electrify the turbocharging as well as to electrically support the power train is an innovative approach to meeting stricter CO₂ regulations through electric hybridisation.



The ambition of the SpeedDrive project is to develop a high-speed drive that far exceeds what was thought possible with the current state of the technology.



PCIM Europe

Fraunhofer IZM presents power highlights at PCIM Europe.

The PCIM Europe is the world's leading exhibition and conference for power electronics, intelligent motion, renewable energy, and energy management.