Design and 2D finite element analysis for a novel magnetic gear integrated brushless permanent machine

Mechanical gears are used extensively for low-speed electrical machine application to reach high system torque density. However, gear lubrication, vibration and reliability can be significant issues. Magnetic gears (MG) can effectively reduce the speed and amplify system output torque through modulation of ferromagnetic pole-pieces and interaction of magnetic field. This paper proposed a novel magnetic gear integrated brushless permanent machine, which overcomes the drawbacks associated with mechanical gear. Compared with previous magnetic gear integrated machines, the novel one is more space efficient and easier to control for putting the brushless permanent machine inside the magnetic gear through mounting the inner-rotor of MG on the brushless permanent machine. This kind of structure integration can make full use of inside-space of MG, and the novel drive train system can reach higher transmission torque density. The operating principle of the machine is discussed and transient performances are analyzed using 2D finite element method (FEM). Detailed analyses about its gear ratio, torque transmission, core losses, and induced voltage are reported.