Design Of Key Structure Of Drilling Direct Drive Permanent Magnet Synchronous Motor

With the gradual decrease of onshore oil and gas resources,the exploitation objects are gradually transferred from the land to the sea.Subsea drilling rig is applied to offshore oil and gas resources exploitation.The drilling direct-drive permanent magnet synchronous motor directly drives the drill bit to carry out drilling and production operations,eliminating the deceleration device and its protection device of traditional electric drilling tools,reducing the downhole transmission chain length,reducing the system failure rate,improving the system efficiency and reducing the system cost.Based on this,the key structure design,electromagnetic parameter optimization and temperature field analysis of drilling direct drive permanent magnet synchronous motor are carried out in this paper.Firstly,the structure design and electromagnetic parameter calculation of the drilling direct drive permanent magnet synchronous motor were carried out for 500 m offshore oil and gas exploitation requirements.Completed the overall scheme design of drilling direct drive permanent magnet synchronous motor,determined the main dimensions such as air gap,stator inner diameter and effective length of single section,and completed the selection of stator core materials and groove size calculation.Decide to use the fractional slot double-layer winding Y type connection,effectively reduce the influence of the third harmonic;Select the high magnetic energy permanent magnet Nd Fe B and calculate its size,using the table stick type installation;The stabilizer bearing is used to fix the motor segment,the bidirectional thrust bearing is used to fix the rotating shaft of the motor axially,and the mechanical seal is used to prevent drilling fluid from entering the stator cavity of the motor.Secondly,the use of taguchi method to the preliminary design scheme of drilling a directdrive permanent magnet synchronous motor is optimized,the selection of the cogging torque and efficiency as the optimization goal,selection of coefficient of air gap,permanent magnet thickness,arc and slotted width in order to optimize the parameters,using the method of orthogonal experiment,experiment,using the method of variance,determine the optimization parameters on the efficiency and the influence degree of the cogging torque are ranking,choose the optimal parameter combination.Maxwell simulation software was used to simulate the optimization parameter combination.Finite element analysis of the motor under no-load and load conditions was completed,and relevant performance parameters and curves were obtained.Finally,the temperature field analysis of drilling direct drive permanent magnet synchronous motor is completed.The heat transfer mode and boundary conditions of the motor were analyzed,and the copper consumption,iron consumption and friction loss were calculated using the finite element method.The finite element model was simplified to determine the thermal conductivity and heat transfer coefficient.Fluent was used to complete the temperature field analysis of the drilling direct drive permanent magnet synchronous motor.According to the conditions of whether drilling fluid is inserted and different drilling fluid flow rates,the temperature field of the motor is analyzed respectively to study the temperature distribution of the motor and verify the rationality of the structure design of the motor.