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Description
Magnetic gears have the advantages of overload protection, no lubrication, fixed transmission ratio, and have broad application prospects in the field of low-speed and high-torque transmission. They can be used for motors, hydro-wind power generation, space gravity-free transmission, etc. Magnetic gears not only have research value for electrical disciplines, but also open up new ideas in various fields such as motors, machinery, and power plants. Therefore, the magnetic gear has more and more research value and significance. Due to the principle of magnetic field modulation, the harmonic content of the air gap magnetic field of the magnetic gear is rich, which will lead to large torque ripple in the transmission process. In order to solve this problem, the structure of the magnetic gear is improved to increase the effective working harmonic of the air gap magnetic field and reduce the harmonic of the pulsation.
In this paper, an eccentric pole coaxial magnetic gear with Spoke structure and Halbach array is proposed. The inner rotor permanent magnet is an eccentric pole Halbach array, and the inner rotor permanent magnet is unevenly distributed. The distribution ratio is 1 : 3 : 1, and the outer rotor permanent magnet is a combination of Spoke structure and Halbach array. In addition, with high output torque and low torque ripple as the optimization objectives, based on sensitivity analysis, response surface method (RSM) and multi-objective genetic algorithm (MOGA) are used to optimize, and the optimization parameters of the improved magnetic gear are determined. A finite element simulation model with the upper pole pairs of inner and outer rotors of 4 and 17 is established.
By comparing with the traditional magnetic gear, it is found that the improved CMG can change the amplitude of the air gap magnetic density. The internal torque fluctuation range is 72.56N·m~74.42N·m, and the external torque fluctuation range is 306.18N·m~313.64N·m. By reducing the magnetic flux leakage, the torque of the CMG can be improved. The output torque of the improved model is 29.35 % higher than that of the traditional model. Reducing the magnetic flux leakage is beneficial to improve the utilization rate of the permanent magnet. At the same time, the torque ripple of CMG is analyzed. The torque ripple of the improved model is 27.48 % smaller than that of the traditional model. Reducing the ripple can make the torque output more stable.
