Analysis And Optimization Design Of Double Fixed Hybrid Permanent Magnet Vernier Motor

When the top drive machine is applied to the top drive system of oil drilling rig,the failure rate and operation and maintenance cost are high due to the transmission mechanism such as mechanical gearbox.The proposal of direct-drive top drive unit provides a solution to this problem.In recent years,the permanent magnet vernier motor(PMVM)with high power density and low speed and large torque has attracted wide attention from academia and industry,and has been preliminarily applied in direct drive fields such as wind power generation and machine vehicles.Based on the analysis of the electromagnetic characteristics of the existing dual-stator PMVM,this paper proposes a new dual-stator PMVM design with hybrid permanent magnet structure,which can realize the on-line flexible adjustment of air gap flux and ensure the efficient operation ability of the top drive unit in the process of large-scale speed regulation.The main research contents are as follows :(1)According to the design process of the motor,the basic parameters are determined according to the technical index requirements.By comparing the effects of different slot pole combinations and winding types on the performance of the machine,a 22 pole 12 slot double stator PMVM for top drive unit is proposed.Each dimension parameter of stator and rotor is optimized by one step,and then the global optimization is carried out by genetic algorithm.A set of non-inferior solutions are obtained in the optimal set by considering the process conditions comprehensively.A 3D virtual prototype model is established on soilworks platform to show the design effect.The electromagnetic characteristics of the designed motor are compared with a straight slot double stator PMVM to verify the rationality of the designed motor.(2)In order to make the designed machine have efficient magnetic flux regulation ability,two different types of permanent magnets are proposed to use series structure excitation.The position and size of low coercivity(LCF)permanent magnet were optimized.The results show that the LCF permanent magnet has good electromagnetic performance when the radial magnetization thickness is 6 mm.The cross-coupling effect of the optimized dual-stator PMVM under two different working conditions is verified by injecting short-time pulse current to change the magnetization state of LCF permanent magnet.(3)Due to the serious magnetic leakage of the dual-stator hybrid PMVM,it is proposed to fill the high temperature superconductor(HTS)in the split tooth to improve this problem.Through the influence of two different types of filling materials on the performance of the motor,the electromagnetic characteristics of the filling material after size optimization are analyzed.The results show that HTS with a thickness of 3 mm can significantly improve the torque output ability of the motor,and the complete magnetic resistance of the material can make the motor efficiency reach 89.26 %.