Design of an aircraft generator with radial force control.

Brecher, Christian; Neus, Stephan; Gärtner, Marcus; Eckel, Hans-Martin; Hoppert, Maik; James, Barry; Gerada, Chris; Degano, Michele; Ilkhani, Mohammad Reza; Di Nardo, Mauro

Abstract

With the increasing electrical energy demands in aviation propulsion systems, the increase in the onboard generators’ power density is inevitable. During the flight, forces coming from the gearbox or gyroscopic forces generated by flight manoeuvres like take-off and landing can act on the generators’ bearings, which can lead to wear and fatigue in the bearings. Utilizing the radial force control concept in the electrical machine can relieve loads from the bearings that not only minimize the bearing losses but also increase bearing life. The objective of the MAGLEV project (Measurement and Analysis of Generator bearing Loads and Efficiency with Validation) is to study, demonstrate, and test a new class of high-speed generators with radial force control.

In this paper, design steps of this type of generator and its test rig are presented and the measurement methodology used for radial force control is explained. The concept is developed in an electrical machine and is validated on a test rig by measuring required parameters like shaft displacement, vibrations and bearing temperature. Additionally, the friction moment of each generator’s bearings is measured and validated in a separate test rig under comparable conditions to the bearing loads in the generator. Therefore, a novel approach to determine precisely the bearing friction in a radial load unit, rotatably supported by an additional needle bearing is used, which shows a good agreement with the calculated friction. Furthermore, new calculation methods for the operating behavior of cylindrical roller bearings with clearance are presented, which are utilized in the generator test rig.

• Journal Article Type: Article
• Acceptance Date: Apr 17, 2023
• Online Publication Date: Apr 17, 2023
• Publication Date: Apr 17, 2023
• Deposit Date: May 4, 2023
• Publicly Available Date: May 24, 2023
• Journal: Open Research Europe
• Electronic ISSN: 2732-5121
• Publisher: F1000 Research Ltd
• Peer Reviewed: Peer Reviewed
• Volume: 2
• Article Number: 73
• DOI: https://doi.org/10.12688/openreseurope.14684.3
• Keywords: validation, shaft-bearing system, test rig, Aircraft generator, bearing friction, bearing loads, radial force control, efficiency
• Public URL: https://nottingham-repository.worktribe.com/output/19789193
• Publisher URL: https://open-research-europe.ec.europa.eu/articles/2-73/v3
• Additional Information: Referee status: Approved, Approved with reservations; Referee Report: 10.21956/openreseurope.16333.r30171, Steffen Ihlenfeldt, Institute of Mechatronic Engineering, Dresden University of Technology, Dresden, 14 Oct 2022, version 2, 1 approved, 1 approved with reservations; Referee Report: 10.21956/openreseurope.16333.r30966, Rubén Lostado Lorza, Department of Mechanical Engineering, University of La Rioja, La Rioja, 28 Mar 2023, version 2, 1 approved, 1 approved with reservations; Referee Comment: Marcus Gärtner; ; Posted: 30 Mar 2023; Dear Prof. Lostando Lorza, Thank you very much for your good and constructive feedback. We have revised our manuscript with regard to your comments and would like to respond briefly. Further information on the radial force sensor has been added to the relevant passage, and a source with further details has also been added. To improve the comparison between measured and calculated friction values, a table was prepared with the percentage deviation. Furthermore a table was added in section 4 giving the missing bearing stiffnesses for a discrete operational point oft he generator bearings. We hope to have clarified your open points and remain with kind regards; Grant Information: This research was financially supported by the European Union’s Horizon 2020 research and innovation programme under the grant agreement No 865364 (Measurement and Analysis of Generator bearing Loads and Efficiency with Validation [MAGLEV]). The Clean Sky Joint Undertaking is a public-private partnership between the European Commission and the European aeronautics industry that coordinates and funds research activities to deliver significantly quieter and greener aviation. The publication reflects only the authors' views and the Joint Undertaking is not responsible for any use that may be made of the information it contains. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.