Optimization Design and Dynamic Characteristics Analysis of Multistage Magnetic Gearbox for MW-scale Wind Turbine

In this article, the multistage magnetic gearbox for wind turbine (WMGB) which contains two-stage magnetic gears (MGs) is studied. The MG is a coaxial MG and consists of outer rotor, modulator and inner rotor. First, the gear ratios of MGs are optimized based on the maximum gravimetric torque density under the constraint of structural parameters. Second, in view of the importance of the first-stage MG (FSMG), the multi-objective optimization method NSGA-II based on back propagation neural network surrogate model is combined with the single parameter scanning method to achieve higher torque performance of FSMG. The simulation results show that the torque density increases by 13.28%, the torque ripple of the modulator and inner rotor decreases to below 5%, and the maximum magnetic force exerted on the modulator is reduced by 22.73%, which verifies the effectiveness and efficiency of the proposed hierarchical optimization strategy. Finally, aiming at the aerodynamic load, the dynamic characteristics of FSMG are analyzed under different wind speed conditions, which verifies the feasibility of the proposed WMGB applied in MW-scale wind power drive systems.