New converter technology for electrolyzers

21.10.2025

Source: E & M powernews

Improving DC power quality, reducing system costs: Fraunhofer researchers have developed a new generation of rectifiers for hydrogen electrolysers.

The production of hydrogen is expensive, and the greatest potential for savings lies in the power supply. In the case of electrolysers, experts see such potential above all in power converter technology. This was the subject of the "HyLeiT" project of the Fraunhofer Institute for Energy Economics and Energy System Technology (IEE), which started four years ago and has now come to an end. In collaboration with the companies SMA Solar Technology and Infineon Technologies, the Technical University of Dresden and the Bonn-Rhein-Sieg University of Applied Sciences, new types of power converters have been developed that ensure lower system costs and an improvement in DC power quality, according to the IEE.

According to IEE project coordinator Norbert Henze, the new rectifiers are based on transistor technologies. "Compared to conventional solutions, the silicon carbide rectifiers developed here can meet grid integration requirements with significantly less effort," he reports. In two parallel development paths, laboratory samples for modular power converters with around 200 kW and 2 MW were created. "These rectifiers not only have a higher power density, but also improved flexibility and efficiency," says the Fraunhofer scientist.

Models for grid integration

In order to study the integration of electrolysis plants into the power grid, the researchers developed "real-time capable dynamic models". "These tools enable us to realistically investigate the interaction between electrolysers and the power grid and to optimize our newly developed rectifiers, which is crucial for system-compatible integration and the stability of the grid," explains IEE grid expert Philipp Strauß.

According to the Fraunhofer Institute, variables such as voltage, current as well as mass and heat flows can be precisely predicted over a wide operating range based on the simulation of microscopic state variables of the electrochemical cells.

Ralf Juchem, project manager at the SMA Innovation Center, expects the project results to "open up the cost advantages and grid serviceability of the large-scale PV/battery inverter platforms much more comprehensively than before for electrolysis converters as well". In addition, functional progress has been made in terms of system integration, system operation and safety of power supply technology for electrolysis systems.

"These developments are crucial to further increase the efficiency and reliability of hydrogen production and thus make a significant contribution to the implementation of the national hydrogen strategy," he says. Developments to make the converter solutions ready for series production are to follow.

Author: Manfred Fischer