Design Of Axial Flux Permanent Magnet Motor For Sandwich Rotor

With the rapid development of society,the demand of people for energy is getting higher and higher.In view of the low efficiency and difficult maintenance of the oil beam pumping unit,this thesis proposes to replace the three-phase induction motor,belt and speed reduction mechanism of the original system with a semi-direct drive shaft motor.According to the working environment and space,an axial flux permanent magnet motor is designed.Because the motor torque needs to increase the rotor strength,that is,increasing the thickness of the permanent magnet.The axial flux permanent magnet motor adopts the sandwich rotor structure for the problem of excessive back electromotive force and permanent magnet waste.In this thsis,the following aspects are studied for the sandwich rotor axial flux permanent magnet motor:Firstly,the related literatures on the axial flux permanent magnet motor topology,air gap magnetic density calculation,temperature rise and loss calculation methods are reviewed,and the application of new materials in axial flux permanent magnet motors is reviewed.Secondly,an axial flux permanent magnet motor is designed for the drive motor for oil field pumping unit.Among them,the performance of the motor with different slot poles is studied.The motor winding is designed by the coil star vector method.The thickness of the permanent magnet is calculated,the rotor strength is calculated,and the axial flux permanent magnet motor rotor is adjusted.Using the ansys maxwell software to model and simulate the motor,the motor performance of the motor back electromotive force,cogging torque and load torque are obtained.Then,the sandwich rotor structure is proposed for the problem caused by the excessive thickness of the permanent magnet.The original permanent magnet is divided into three pieces,and the middle part is replaced by a magnetic conductive material.The relationship between the air gap magnetic density and the thickness of the rotor core is calculated by analytical method,and the relationship between the air gap magnetic density and the thickness of the rotor core is obtained by the finite element method.The optimal solution is obtained when the sandwich thickness is 10 mm.Modeling and simulation of the axial flux permanent magnet motor of the sandwich rotor,the simulation results meet the design requirements.Finally,for the permanent magnet eddy current loss is too large,the principle of permanent magnet eddy current loss is analyzed,and the block method is used to reduce the permanent magnet eddy current loss.The circumferential and radial sections of the permanent magnets are studied separately,and the conclusion that the circumferential block is better than the radial block is obtained.The circumferential direction is divided into 4 blocks,and the block is performed in the radial direction,and the effect is not obvious.Finally,the permanent magnet is divided into four sections in a circumferential direction to reduce the eddy current of the permanent magnet.Through finite element simulation,the permanent magnets are compared with the blockless axial flux motor and the non-blocking is performed.The eddy current loss of the permanent magnet is reduced,and the performances of other load torque and back electromotive force are not weakened.