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Low-RPM torque converter (LRTC) with Integrated direct shaft flywheel
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Electricity.
2023 (English)In: International Marine Energy Journal, E-ISSN 2631-5548, Vol. 6, no 1, p. 1-10Article in journal (Refereed) Published
Abstract [en]

The low-RPM Torque Converter (LRTC) is a rotating generator concept for use on the seabed with the driving force from sea waves motion on the sea surface. This concept is built up of two identical generators connected opposite each other via a spring drum with a built-in ball bearing clutch. The drum is connected to a buoy on the sea surface via a wire, the wire is rolled around the spring drum. With sea waves, the buoy moves either upwards or downwards and pulls the wire upwards or downwards. This movement causes the generators to spin.

This article presents an upgrade of the LRTC generator concept and upgraded measurement system, both hardware and software.

A flywheel system of the thin-disc type has been designed for direct connection to the generator's rotor shaft and an electronic measuring system has also been developed for more accurate measurements and minor disturbances.

More detailed tests have been performed both for the purpose of comparing the systems and to explore the performance of the generator concept in more detail.

Three different experiments have been done in this article. The first two experiments were performed to investigate the performance of the flywheel and to see the performance of the LRTC system with and without flywheel.

The third experiment investigated the optimization of the flywheel mass by increasing the mass of the flywheel with the addition of more thin discs.

All movements are simulated with a six-joint industrial robot. Several sinusoidal types of wave motions have been simulated with different time periods and also several real wave climate motions (data taken from fields) have been simulated with the robot. The experiments show that the addition of the flywheel in the LRTC system provides advantages in increasing both peak power, average output power and also softens the output power oscillation.

Place, publisher, year, edition, pages
2023. Vol. 6, no 1, p. 1-10
Keywords [en]
LRTC; Flywheel; Robot; Generator; Wave energy; Renewable energy
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:uu:diva-501121DOI: 10.36688/imej.6.1-10OAI: oai:DiVA.org:uu-501121DiVA, id: diva2:1754055
Available from: 2023-05-02 Created: 2023-05-02 Last updated: 2024-12-10
In thesis
1. Industrial robot as main equipment for testing and production of Wave Energy Converters
Open this publication in new window or tab >>Industrial robot as main equipment for testing and production of Wave Energy Converters
2025 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since 2001, research and development on the conversion of ocean wave energy into electricity has been conducted at the Division of Electricity at Uppsala University. Different Wave Energy Converter (WEC) technologies has been developed, such as the point-absorber linear Uppsala University WEC (UU-WEC) and the Low-RPM Torque Converter WEC (LRTC-WEC). 

This thesis focuses primarily on the development of a robotized dry test rig, to facilitate assessment of different WEC technologies in house. An existing industrial six degrees of freedom robot system is used to emulate buoy movement on the sea surface, with regard to the impact of hydrodynamic forces in real time. Two different methods for integrating a hydrodynamic model to the robot controller are presented: the force control and the position control methods. Both methods are evaluated and validated across various regular and irregular wave climates, as well as for different theoretical buoy shapes.  

The secondary focus in this thesis is the development of robotized production methods for the UU-WEC. The surface mounting of Neodymium Iron Boron (Nd2Fe14B) magnets and the cutting of rubber discs are investigated, resulting in viable solutions that include development and validation of robot tooling and robot cell proposals. 

A smaller segment of the thesis examines the use of robotics in teaching a course for bachelor engineering students. At the outbreak of the COVID-19 pandemic a challenging task was imposed: a swift shift to online distant education. A major task was to replace physical lab exercises with video recordings, detailed instructions and simulated laboratory environments. The results indicated that the upgraded online education successfully meet the course objectives.

The final part of the thesis investigates the use of WECs for powering a desalination plant. Desalination presents a viable solution for islands or coastal regions deficient in freshwater resources, but is also an energy intensive process. Practical experiment evaluated the possibility of utilizing the UU-WEC as power source for desalination plants.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2025. p. 78
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 2485
Keywords
Dry test rig, Industrial robotics, Manufacturing automation, Large-scale production, Linear generator, Wave energy converter, Engineering education, Desalination
National Category
Robotics and automation Other Electrical Engineering, Electronic Engineering, Information Engineering Communication Systems Control Engineering
Research subject
Engineering Science with specialization in Science of Electricity; Engineering Science with specialization in Electronics; Engineering science with specialization in Applied Mechanics; Engineering Science with specialization in industrial engineering and management; Electrical Engineering with specialization in Automatic Control; Engineering Science with specialization in industrial engineering and management
Identifiers
urn:nbn:se:uu:diva-544285 (URN)978-91-513-2337-4 (ISBN)
Public defence
2025-02-10, Polhem, Lägerhyddsvägen 1, 75237 Uppsala, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2025-01-17 Created: 2024-12-10 Last updated: 2025-02-05

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Salar, DanaHultman, ErikSavin, Andrej

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