Rotor cooling of low-inertia induction machines for highly dynamic applications

• Applicants: Professor Dr.-Ing. Jochen Fröhlich; Professor Dr.-Ing. Wilfried Hofmann
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives ; Fluid Mechanics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 507287551

Highly dynamic electric asynchronous machines, such as those used in testing and production facilities, are characterized by extremely frequent torque changes, where a cycle may also comprise a single revolution only. This requires a construction with a low moment of inertia, and above all, the massively increased heat loss compared to other machines must be safely removed. The aim of the project is to investigate a new cooling system with air radially guided through rotor and stator providing such an intense heat removal. Rotor and stator channels are coupled via the gap, and the flow through the rotor occurs with complete reversal of direction, which leads to complicated phenomena. Second, the novel design and the highly dynamic operation result in complex electromechanical conditions that must be understood and controlled as well. The investigation of the interaction between design, electromechanical, thermal, fluid mechanical and application-determined aspects requires a cross-disciplinary approach, which is realized by the collaboration of the two applicants. Methodical tools from the field of electrical machines and from the field of fluid mechanics are combined in a thoroughly coordinated manner to investigate phenomena on different length scales. This ranges from a disk model as a reference experiment, supplemented by highly resolving simulations of flow details, to a network model of an example machine, which allows the evaluation of the concept in the sense of a numerical demonstrator. The aim of this fundamental project is to gain a detailed understanding of the multi-physical phenomena associated with the novel cooling concept, an overall evaluation, and a clear statement on application perspectives for industrial use.

• DFG Programme: Research Grants