Design, construction, and analysis of a large scale inner stator radial flux magnetically geared generator for wave energy conversion

A magnetically geared machine (MGM) integrates a magnetic gear with a low torque, high speed electric machine to create a single compact high torque, low speed device with the size advantages of a mechanically geared system and the reliability of a direct drive machine. This work investigates the use of MGMs for wave energy conversion through the development of a large scale magnetically decoupled inner stator radial flux magnetically geared generator rated for 10 kW at an input speed of 30 rpm. Critical design trends are illustrated using parametric 2D and 3D finite element simulation results. Information is also provided about the prototype's mechanical structure and key magneto-mechanical design considerations, including the impact of modulator bridges and the extent of axially escaping leakage flux. The prototype's experimental stall torque of 3870 N·m represents a 99.1% match with the simulated stall torque and corresponds to volumetric and gravimetric torque densities of 82.8 kN·m/m
³
and 14.5 N·m/kg, respectively. Additionally, the prototype achieves an experimental efficiency of approximately 90% over much of its operating range.