Nonlinear magneto-mechanical combined vibration characteristics of magnetic gear two-speed transmission

The replacement of mechanical planetary gears with magnetic gears (MGs) is an emerging transmission solution for electric vehicles that reduce shock and vibration. This article proposes magnetic two-speed transmission and examines the influence of the noncontact torque of MGs, the meshing stiffness of mechanical gears, and the system load on the vibration of magneto-mechanical combined transmission systems. First, the noncontact torque of an MG is analysed on the basis of the magnetic field modulation principle. A set of dynamic equations was subsequently constructed on the basis of the centralized parameter method. Thereafter, with the principle of harmonic balance, a rapid method for constructing a nonlinear vibration harmonic balance solution for a magneto-mechanical combined vibration system in matrix form is obtained. Finally, simulations and prototype tests were conducted. The results show that noncontact torque consists of stable torque and ripple torque. They also interact with mechanical gears to affect system vibration. he vibration amplitude of the inner rotor is sensitive to the pulsating torque, whereas the vibration of the ferromagnetic pole-pieces is sensitive to the meshing stiffness. The stable torque and load dynamic balance affect the natural frequency of the system. The system demonstrates “load‒stiffness adaptive” characteristics compared with those of pure mechanical gearing. The proposed Harmonic Balance Method can quickly calculate this characteristic, and it offers a theoretical basis for dynamic analysis and vibration reduction in magnetic two-speed transmissions.