Hasanpour, Shima (2021-12). Magnetic Gear Design for High-Speed Applications. Master's Thesis. Thesis uri icon


  • Magnetic gears perform the gearing action by employing magnetic fields through a non-contact operation that offers significant potential advantages, such as improved reliability, reduced acoustic noise, and reduced maintenance requirements, over mechanical gears due to eliminating teeth interlock for the power transfer. Utilizing magnetic gears in high-speed applications has electromagnetic and mechanical challenges. This study investigates solutions, introduces new topologies with different magnet arrangements, and compares various magnetic gear designs. First, the coaxial reluctance magnetic gear (RMG) and the coaxial surface permanent magnet gear (SPMG) topologies are optimized independently. Coaxial SPMGs are found to achieve higher torque densities, better magnet utilization, higher efficiencies, and lower torque ripples than optimal coaxial RMGs. Second, this study introduces the radial flux reluctance cycloidal magnetic gear (Rel- CyMG) topology and its operating principles. The Rel CyMG replaces the PMs on the inner rotor of a surface permanent magnet (SPM) cycloidal magnetic gear (CyMG) with teeth and slots and requires half of the SPM CyMG's outer rotor pole pair count to achieve the same gear ratio. A genetic algorithm was used to optimize RelCyMGs, SPMCyMGs, and SPM coaxial magnetic gears (CoMGs). This study demonstrates that SPMCyMGs significantly outperform the other two topologies at higher gear ratios in terms of torque density. However, RelCyMGs achieve higher torque densities than SPMCoMGs at higher gear ratios. RelCyMGs eliminate the required PM retention sleeve and potentially enable smaller air gaps in the optimal designs. Third, this research compares CyMG topologies with consequent pole (CP) rotors against CyMGs with SPM rotors. CPCyMGs require less PM pieces than SPMCyMGs, which may simplify manufacturing. The simulation results demonstrate that optimal CP- CyMGs achieve lower torque density values than optimal SPMCyMGs. However, if using a CP inner rotor eliminates the need for a PM retention sleeve and enables the use of a smaller effective air gap, CPCyMGs can achieve higher torque densities at high gear ratios than SPMCyMGs. Last, a CPCyMG prototype is designed, optimized for cost objective, fabricated, and tested to validate the accuracy of the model. Its experimentally measured slip torque achieved a 95% match with the simulated slip torque.

publication date

  • December 2021