The Low-RPM torque converter (LRTC) with Integrated direct shaft flywheel


  • Dana Salar Uppsala University
  • Erik Hultman Uppsala University
  • Andrej Savin Uppsala University



LRTC; Flywheel; Robot; Generator; Wave energy; Seabased renewble energy.


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.




How to Cite

Salar, D., Hultman, E., & Savin, A. (2023). The Low-RPM torque converter (LRTC) with Integrated direct shaft flywheel. International Marine Energy Journal, 6(1), 1–10.



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