Abstract: Multi-shafts ring-plate magnet gear (MRMG) structure is proposed. In order to quantitatively analyze its unique flat pendulum motion mechanism and transmission characteristics, the air-gap magnetic density and electromagnetic torque generated by the eccentric magnetic field are solved, and the power flow process of internal branch and optimal transmission mode are obtained. Firstly, the motion relation of inner and outer permanent magnet rings is correlated based on MRMG operating characteristics, and the relationship between the MRMG dynamic torque and speed is intuitively expressed by dynamic model graph with the feedback mechanism. Then, by using vector magnetic potential method, the MRMG eccentric magnetic field is transformed into concentric magnetic field by linear fraction transformation, so as to solve the air-gap magnetic density and torque under the magnetic field, and obtain the balance relationship and loss model between the inner and outer permanent magnet rings and each shaft. Because the model established includes mechanical bearing losses that cannot be taken into account by FEM, the calculated speed ratio, torque ratio and efficiency are closer to dynamic measured results. In addition, due to the MRMG power split characteristics, its operation characteristics is optimal when all eccentric shafts bear the same load, followed by the eccentric shafts bearing with load deviation mode, single input/single output mode is the lowest, the maximum measured efficiency is only 73.72% of optimal mode.

Key words: multi-shafts ring-plate magnet gear, dynamic analysis, air-gap field, electromagnetic torque, dynamic experiment