Optimization of superconducting dynamos for the contact-free charging of superconducting coils

• Applicant: Dr. Ruben Hühne
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives ; Synthesis and Properties of Functional Materials
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562988087

A superconducting dynamo enables the contactless powering of superconducting coils and circuits eliminating the need for normal conducting power leads with a large cross-section between the warm environment and the deep-cooled superconducting coil. It has the advantage that these leads no longer act as a thermal bridge between the cold side of the cryostat and the warm environment. At the same time, Ohmic losses due to high currents in the current leads are avoided. As a result, the required cooling power of the system might be significantly reduced. In general, a superconducting dynamo consists of a superconducting coated conductor, a rotating arrangement of permanent magnets and potentially an additional iron yoke. The coated conductor is usually connected to the superconducting coil that is to be charged. During operation, the permanent magnets are continuously guided over the coated conductor. The electromagnetic interaction between the permanent magnets and the superconducting layer induces a voltage in the conductor, which leads to a current flow in the connected coil. Due to the purely electromagnetic interaction between permanent magnets and the coated conductor, such superconducting dynamos can operate even through a cryostat wall, which further reduces thermal losses as no moving parts are on the cold side. In most systems investigated so far, long charging times have to be accepted due to the low dynamo efficiency. In addition, undesirable eddy current losses occur at high charging frequencies. Therefore, the aim of the project is to significantly improve the efficiency of such a superconducting dynamo by optimizing the individual components (coated conductors, permanent magnets, etc.) in such way that superconducting coils can be charged faster and with lower losses. Among other things, this includes maximizing the magnetic flux density in the coated conductor while minimizing stray fields by means of new magnetic field arrangements and yoke geometries. At the same time, it is studied how eddy current losses might be minimized at high magnetic passage frequencies. A superconducting magnetic bearing might be implemented for this purpose. In summary, it is expected that the investigations within the project will make decisive contributions to the use of superconducting dynamos for the efficient charging of superconducting coils. In order to achieve this goal, the experimental investigations will be accompanied by numerical simulations. On the one hand, this enables faster optimization of the individual components, whereby the simulation results are repeatedly verified in experimental investigations in order to improve the model. At the same time, the model developed for the complete system forms the basis for adapting such a superconducting dynamo to future application scenarios.

• DFG Programme: Research Grants
• Co-Investigator: Dr.-Ing. Tilo Espenhahn