Open AccessExact magnetic field analytical model for eccentric magnetic harmonic gears using hyperbolic cotangent transformation
Author(s) -
Liu Ronghui,
Zhao Zengkai,
Sun Gaiping,
Mi Yang,
Lin Shunfu,
Tang Jing
Publication year - 2020
Publication title -
iet electric power applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.815
H-Index - 97
eISSN - 1751-8679
pISSN - 1751-8660
DOI - 10.1049/iet-epa.2020.0546
Subject(s) - permeance , air gap (plumbing) , magnetic field , stator , magnetic flux , mathematical analysis , mechanics , superposition principle , magnetic reluctance , physics , magnet , finite element method , trigonometric functions , mathematics , geometry , materials science , permeation , genetics , quantum mechanics , membrane , composite material , biology , thermodynamics
The eccentric magnetic harmonic gear (EMHG) utilises the change of the magnetic permeability caused by eccentric structure to achieve large torque transmission with high gear ratios. This study presents an exact EMHG analytical model based on the hyperbolic cotangent transformation method. The exact method has no truncation errors and thus it is appropriate for the analysis of magnetic fields in the EMHG with large eccentricity. Firstly, the eccentric air‐gap magnetic field distributions are obtained by modulating the concentric magnetic field distributions with the relative permeance function. Then, the air‐gap flux density of the EMHG is obtained according to the superposition of the flux density by the eccentric rotor and stator permanent magnets acting alone. Furthermore, the analytical results of the air‐gap flux density and electromagnetic torque are compared with those of the finite‐element method, which verifies the correctness and validity of the analytical model. Finally, the experimental measurements on the dual‐stage EMHG confirm the validity of the analytical prediction.