Analysis and Design Optimization of a Coaxial Surface-Mounted Permanent-Magnet Magnetic Gear

Abstract

This paper presents the analysis and design optimization of a coaxial surface-mounted permanent-magnet magnetic gear. The magnetic field distribution in the coaxial magnetic gear is calculated analytically in the polar coordinate system and then validated by the finite element method (FEM). The analytical field solution allows the prediction of the magnetic torque, which is formulated as a function of design parameters. The impacts of key design parameters on the torque capability are then studied and some significant observations are summarized. Furthermore, the particle swarm optimization (PSO) algorithm is employed to optimize the studied magnetic gear. Given that the torque capability and material cost conflict with each other, both of them are set as the optimization objectives in this paper. Different weight factors may be chosen for the two objectives so that more attention can be placed on one or another. The results shows that the highest torque density of 157 kNm/m 3 is achieved with the consideration focusing on the torque capability only, then the highest torque per permanent magnet (PM) consumption could be improved to 145 Nm/kg by taking the material cost into account. By synthesizing the torque capability and material cost, a 124 kNm/m 3 of torque density and a 128 Nm/kg of torque per PM consumption could be achieved simultaneously by the optimal design.

Power Characteristics Analysis of a Novel Double-Stator Magnetic Geared Permanent Magnet Generator

“…Research in magnetic gearing has increased in the last 10 years because of its potential for efficient transmission torque, lubrication free maintenance, overload protection and non-contact operation compared to problems of mechanical gears [1]. Studies [2][3][4][5][6][7] have shown that magnetic gears can reach a torque density of 100 kNm/m 3 and by integrating a magnetic gear with a PM machine; the resultant magnetic geared machine can be applied in low-speed high torque applications such as traction motors and as generators in low-speed renewable energy power generation [8,9]. Reference [10] reported that a double-stator PM machine achieved a higher torque density much greater than a single-stator PM machine.…”

A Novel Double-Stator Permanent Magnet Generator Integrated With a Magnetic Gear

“…In the last 10 years, research in magnetic gears has increased because of their potential for efficient high torque transmission, inherent overload protection, lubrication-free operation and lower acoustic noise when compared with mechanical gearboxes [2]. Also various types of magnetic gears such as coaxial magnetic gears [3,4], linear magnetic gears [5] and axial magnetic gears [6,7] have been proposed and reported to have a transmitted torque density greater than 100 kNm/m 3 . The coaxial magnetic gear concept seems to have attracted much attention because of their good utilization of PMs and high transmission torque density.…”

A Novel Flux Focusing Magnetically Geared Machine with Reduced Eddy Current Loss

“…In recent years, magnetically geared (MG) machines have attracted much attention [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. MG machines incorporate a PM brushless machine and a magnetic gear into one volume.…”