| As the power source of top drive drilling system,the performance of top drive machine is directly related to the success of drilling operation.Because the motor for direct drive top drive drilling system generally requires to work at a lower speed to obtain a larger torque,there are some problems such as large machine volume,high cost,transportation,and installation difficulties.In addition,the torque density of traditional direct drive permanent magnet synchronous machine is difficult to be further improved.Therefore,two kinds of consequent pole permanent magnet vernier machine with high torque density are proposed to achieve low speed and high torque direct drive,and overcome the problem of excessive permanent magnet consumption in traditional permanent magnet vernier machine.The main research contents are as follows.Based on the principle of magnetic field modulation,two kinds of topology of inserted and spoke-array consequent pole permanent magnet vernier machine are proposed.The main design methods and criterion are analyzed,and the power size equation is derived.According to this equation,the initial size parameters of the machine are calculated.Combined with the finite element method,the relationship between the main structural parameters and the output torque of the machine is explored,the final size parameters of the machine are determined,and the finite element analysis model of the machine is established to analyze its static electromagnetic characteristics.Based on the inserted consequent pole permanent magnet vernier machine(ICP-PMVM),a kind of inserted consequent pole hybrid permanent magnet vernier machine(ICP-HPMVM)was developed by introducing low coercive force permanent magnet,which improves the ability of adjusting the air gap magnetic field of ICP-PMVM.Based on the analytical model of magnetic circuit,the magnetization characteristics of the low coercive force permanent magnet are discussed.Considering that the cross-coupling effect in the machine will cause partial demagnetization of the low coercive force permanent magnet,which increases the difficulty of on-line precise magnetic regulation,the cross-coupling effect in the machine and the ideal conditions to eliminate this effect are studied.At the same time,the static electromagnetic characteristics and magnetic characteristics of the machine are analyzed,and compared with the ICP-PMVM,which reflects the advantages of the new structure machine.Due to the flux barrier effect,the magnetic flux density of the stator yoke decreases,which limits the improvement of the torque performance of the spoke-array permanent magnet vernier machine(SA-PMVM).The flux path is changed and the flux barrier effect is weakened by the rotor Γ-slot design of the spoke-array permanent magnet vernier machine with consequent-pole(SA-CP-PMVM).In addition,the use of permanent magnets and the machine cost is significantly reduced by using consequent-pole,Through the establishment of the magnetic circuit analytical model of the machine,the working principle is analyzed,and the static electromagnetic performance of the machine is analyzed by using the finite element method.Compared with SA-PMVM with the same volume and heat duty,the results show that SA-CP-PMVM can obtain better torque performance on the premise of significantly reducing the consumption of magnetic steel. |
