DC Grids

The massive expansion of renewable energy sources will involve a wealth of change in electrical energy supply. An important aspect arises out of the transition from a centralized to a highly decentralized supply system.

For reducing system costs and achieving highest efficiency in providing electric energy, DC based systems and grids will play key roles in the future. This is due to the intrinsic DC characteristic of the main elements, like photo­voltaic generators and electrical energy storages, and the elimination of many inefficient DC-to-AC and AC-to-DC conversion steps in the case of direct supply of the large number of electronic loads.

We at Fraunhofer IISB are happy to support you with power electronics, protection technology, grid analysis and stability for DC applications.

»eMobiGrid« Joint Project 

The project partners in eMobiGrid are working on a comprehensive energy infrastructure that supports the efficient integration of sustainable energy sources and facilitates the further development of electromobility. As a solution, the focus in eMobiGrid is on local and decentralized DC grids. These enable low-loss coupling of renewable energy sources and battery storage and are suitable for the integration of charging stations for different types of electric vehicles. The key components within these DC grids are efficient, reliable and safe DC/DC converters.

In eMobiGrid, the DC Grids group at the IISB is developing a particularly flexible, insulating DC/DC converter. Due to its ultra-wide voltage range, this converter is specifically optimized for bidirectional DC charging. This means that, in addition to passenger cars, commercial vehicles can also be charged and discharged. Bidirectional charging allows the batteries of electric vehicles to be used as intermediate storage in the DC grid. In this way, they buffer the overproduction of renewable energies. The bidirectional charging technology is therefore particularly important for grid stability when the energy supply fluctuates

Project Partners: Richter R&W Steuerungstechnik GmbH, eCharge Hardy Barth GmbH, EnQs gmbH, Lehrstuhl Mess- und Regeltechnik (MRT) (University Bayreuth)

Funding: eMobiGrid is funded by the German Federal Ministry for Digital and Transport (BMDV) within the framework of the "BMDV Electric Mobility Funding Guideline" with approximately three million euros. The funding program is coordinated by NOW GmbH and implemented by Projektträger Jülich (PtJ).

Press Release: Published on 17/05/2023 in German

The Fraunhofer IISB office and lab building is already equipped with a DC grid system. We steadily increase and optimize this DC application platform to achieve a maximum in efficiency, functionality, and user comfort.

All necessary key components are developed at Fraunhofer IISB together with our industrial partners. Examples are a battery storage system, different DC/DC and AC/DC converters, a DC Grid Manager for controlling the energy flow, and several safety components for typical DC grids in 380 VDC or ±380 VDC configurations. A proprietary DC fast charging solution allows the cost effective realization of e-car charging stations.

This unique platform is open also for our industrial partners and offers:

• Application-oriented testing of DC micro and nano grid components
• Data acquisition under realistic operational con­di­tions
• Optimization of the energy flow between different sources, loads, and energy storage devices; evaluation of control strategies
• Education and advanced trainings in the field of next generation power supply and local grid technologies