Electrical Energy Systems

How can companies save energy using direct current?

Many production systems use power converters with efficiencies above 95%. However, multiple conversion stages still lead to unnecessary energy losses.

Together with industry and research partners, we have developed a power supply system that uses direct current (DC) for energy transmission. This reduces conversion steps and enables the reuse of energy stored within processes.

Measurements on CNC machines show energy savings of more than 6% per operating cycle, and up to 9% in robotic cells.

We work closely with the Open Direct Current Alliance (ODCA) and Current/OS and have jointly contributed to the development of VDE SPEC 90037, a forward-looking pre-standard for the design of sustainable and future-proof DC grids.

Are low-voltage DC grids ready for deployment?

They are considered a key technology for efficient and flexible energy systems. Initial implementations are already in operation, but questions regarding standardization, protection concepts, and system configuration remain open.

Our research focuses on the model-based design, monitoring, and control of DC grids, with the goal of ensuring reliability, efficiency, and scalability.

A particular focus is on fault management. Unlike AC systems, DC grids do not yet benefit from fully established protection mechanisms. Using simulations, digital twins, and streamlined measurement approaches, we develop new solutions for fault detection and grid stability.

In our labs, we work closely with industry partners to develop and validate practical solutions under real-world conditions. We also support companies in testing components and analyzing the behavior of DC grids.

Our goal is to deliver practical, standards-compliant, and scalable solutions for the safe deployment of DC grids – from industrial applications to building integration.

How does electromobility contribute to grid stability?

The electrification of vehicle fleets places increasing demands on existing power grids. Peak loads and limited grid connection capacities make intelligent charging infrastructure essential.

While AC solutions remain the current standard, DC systems offer clear advantages, including reduced conversion losses, improved integration of photovoltaics and storage systems, and reduced material use in copper and transformers.

A particularly promising approach is bidirectional charging. Vehicles can not only consume energy but also feed it back into the grid. This enables batteries to act as flexible storage systems – for peak shaving, increased self-consumption, and grid stabilization.

We support companies in planning and operating charging infrastructure – from grid and load analysis to the selection of suitable system configurations.

In research projects, we also develop control strategies for grid-supportive charging systems, including:

• Load management based on electricity prices and local energy generation
• Consideration of vehicle usage patterns and state of charge
• Techno-economic comparison of unidirectional and bidirectional concepts

Our goal is to enable interoperable charging infrastructure that delivers added value for both companies and the energy system.

How does hydrogen change power supply systems?

Hydrogen is a key element of the energy transition. Electrolyzers and fuel cells inherently operate on direct current (DC), but are typically connected to AC grids, resulting in additional conversion losses.

Direct integration into DC grids avoids these losses and improves both efficiency and economic performance, particularly in continuous operation.

Key focus areas

• Energy and economic analyses
  Comparison of AC and DC system architectures, efficiencies, and total cost of ownership
• System design and dimensioning
  Selection of suitable converters, as well as protection and filtering technologies
• Control strategies
  Approaches for load shifting, grid-supportive operation, and the use of surplus energy

Our goal is to enable the practical and cost-effective integration of hydrogen systems into DC grids, enhancing flexibility and supporting a CO₂-neutral industry.

What role do medium-voltage DC grids play in the energy transition?

Low-voltage DC grids are typically limited to 1,500 V. Above this range, systems are classified as medium voltage. The voltage range from 1.5 to 10 kV offers significant potential for energy-intensive applications such as data centers, shipbuilding, and process industries. It also enables efficient coupling of multiple low-voltage DC grids in both AC and DC environments.

However, important challenges remain, including the lack of standards, clearly defined voltage levels, and reliable protection concepts. In collaboration with research partners, we address these gaps through modeling, techno-economic analyses, and simulation-based studies.

Key focus areas

• Definition of voltage levels and standardization
  Development of practical voltage levels to ensure planning reliability and device compatibility
• Control and energy management
  Analysis of dynamic interactions when interconnecting multiple DC grids
• Protection concepts and fault analysis
  Evaluation of protection strategies based on simulation of complex fault scenarios

Our goal is to enable a robust and scalable medium-voltage DC infrastructure as a key enabler for technologies such as hydrogen, energy storage, and sector-coupled energy systems, contributing to standardization, supply security, and efficiency at industrial scale.