Investigation and Optimization of a Magnetic Geared Permanent-Magnet Machine for Torque Density Improvement

Magnetic geared permanent-magnet machine (MGPM) is considered ideal for high-torque direct drive applications. In this paper, a new topology of MGPM for torque density improvement is proposed and optimized. First, based on the analytical model of MGPM, the analytical expression of transmission torque is derived, and the dominant components are identified, which in turn are used to increase the transmission torque by maximizing the working flux density harmonics through topology innovation. Then, a multilevel objective-layered optimization method is introduced to reduce the complexity and increase the efficiency of the optimization process. Finally, simulation results are presented to demonstrate that the proposed MGPM can operate at high output torque density over 130 Nm/L.