Torque Density Design Optimization of Rotating Pole Piece Concentric Magnetic Gear

Magnetic gears are a force transmitter consisting of permanent magnets. The mechanical input can be transmitted to an output shaft without contact by magnetic forces. The magnetic gears are not worn out because there is no friction. As a result, the running costs such as the maintenance fee can be suppressed and the resources can be saved. However, the transmission torques of the conventional magnetic gears, which have so far been developed, are very low. Besides, new structure models designed for high torque density need a lot of permanent magnets and multi-pole constructions. Those structures are complex and the manufacturing is difficult. In this research, we applied a flux concentration type surface permanent magnet arrangement to a surface permanent magnet type magnetic gear in order to improve the transmission torque and to reduce the amount of permanent magnets. The magnetic flux distribution, the gap flux density and the transmission torque of the developed new models are numerically analyzed by using the two-dimensional finite element method. In this paper, a permanent magnet structure optimized to reduce its amount and influence of the flux concentration type surface permanent magnet arrangement on the gap flux density distribution and transmission torque are reported.

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Spectrum Analysis and Optimization of the Axial Magnetic Gear with Halbach Permanent Magnet Arrays

Energies ◽

10.3390/en12102003 ◽

2019 ◽

Vol 12 (10) ◽

pp. 2003

Author(s):

Fang Hu ◽

Yilan Zhou ◽

Hesong Cui ◽

Xiao Liu

Keyword(s):

Permanent Magnet ◽

Axial Force ◽

Spectrum Analysis ◽

Parametric Analysis ◽

Air Gap ◽

Torque Density ◽

Output Torque ◽

Magnetic Gear ◽

The Difference ◽

Force Calculation

In order to study the contribution of each harmonic to the output torque and axial torque of the axial magnetic gear with Halbach permanent magnet arrays (HAMG), torque and axial force calculation formulas of the HAMG are proposed based on the air-gap flux density distribution of the HAMG. Because of the difference of the air-gap flux densities at different radii, two simplified torque and axial force calculation formulas are proposed and compared. To improve the torque capability of the HAMG, parametric analysis of eight dimensional parameters is firstly conducted. By parametric analysis, six parameters such as the inner radius have been found to have obvious impact on the output torque and output torque density of the HAMG. The optimization using Maxwell software is then executed for maximizing the output torque density of the HAMG. The output torque density of the optimized HAMG is improved from 78.1 kNm/m3 to 93.3 kNm/m3 with an increase of 19%. Furthermore, spectrum analysis is also presented to illustrate the significant output torque improvement based on the torque calculation formulas.

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