Development of a High-Performance Magnetic Gear

TLDR

The analyzed permanent‑magnetic gear has a 5.5:1 ratio and can deliver 27 N/spl ⋅ m. The study presents calculation and measurement results of a high‑performance permanent‑magnetic gear and validates the analysis to predict its efficiency. The gear was constructed and a systematic loss analysis was performed to explain its 81 % efficiency, identifying magnetic bearing losses and end‑effect reductions. The results show that the gear’s low torsion spring constant and end‑effects reduce torque, magnetic bearing losses limit efficiency to 81 % (potentially 96 % with design changes), and magnetic gears outperform mechanical gears in efficiency while maintaining comparable torque density, indicating a shift toward magnetic gear technology.

Abstract

This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses of magnetic origin in the bearings and less end-effects caused by relatively short stack, an impressive efficiency estimated at 96% can be obtained. Comparison with classical mechanical gears has shown that the magnetic gear has a better efficiency and a comparable torque per volume density. Finally, it is concluded that the results in this paper may help to initiate a shift from mechanical gears to magnetic gears.