Optimization Design And Analysis Of Magnetic Gear With Damper Windings

Compared with conventional mechanical gears,field modulated magnetic gears(FMMG)have certain potential for torque and speed transmission in practical engineering as the merits of intrinsic overloading protection feature and non contacted configuration.However,Magnetic gear always experience transient oscillations due to their non-rigid magnetic coupling between two rotors while undergoing starting and changes in speed or load.Most of the extent researches on magnetic gears are mainly about the static and steady performance,while few research methods are proposed for improving the dynamic stability of the whole transmission system.According to the characteristic that the low torsional stiffness of magnetic gears,and combined with the working principle of damper windings using in synchronous machines with permanent magnets(PMs),a novel magnetic gear with damper windings is proposed.The magnetic field analysis,optimization design,dynamic performance,losses and efficiency are all studied in detail.The main research contents of this thesis are as follows:Firstly,the configuration of the magnetic gear with damper windings is proposed.The relationship between the harmonic frequency of double air-gaps and the PM pole pairs of the two rotors is analyzed by mathematical method,which explained the working principle.Based on this,the the finite element analysis(FEA)of the FMMG is carried out,and introduced the application of electromagnetic field analysis software.It's two-dimensional static magnetic field performance,torque characteristic of magnetic gear,and the stable operation point are studied.Increasingly,by analysis the important parameters of magnetic gear,the changing rule of the maximum static torque and the torque density with the parameters increasing is obtained.Parameters above are further optimized by orthogonal design,and the best sizes are acquired by range analysis.Secondly,according to the composition principle of transmission system,the motion equations of it is established,the equivalent model of the magnetic gear with damper windings in the dynamic case is given,so the effect of damper winding on transient state is illustrated theoretically.The dynamic performance characteristics,including no-load starting,with load starting,sudden disturbance and over-load feature are all analyzed.This thesis also show out the transient behavior comparisonwaveforms of the magnetic gear with and without damping windings.The influence of the damping windings parameters on the dynamic performance of the magnetic gear is analyzed by setting the adjusting time as the optimization goal,and it is clear that the adjusting time has a direct variation with the damper windings parameters,the stability of the system is improved by selecting the suitable parameters.Finally,the losses and efficiency of magnetic gear are analyzed.Based on the theoretical analysis of the loss generation mechanism,the loss distribution of each part of the magnetic gear is calculated with FEA,the simulation results of losses under different speed with and without damper windings are shown out.According to the efficiency formula,the relationship between the efficiency and load under different speed of the magnetic gear is obtained.The results show that the efficiency is higher with large load in a certain range when the rotor at the same speed,and the magnetic gear is suitable for working under the condition of low speed and high torque.The prototype has been developed to illustrate the accuracy and efficiency of this structure.