| Mechanical couplings usually use mechanical force to transmit motion and torque directly through direct contact,resulting in the problem of vibration transmission.Under the condition of large vibration and sudden load,the service life of components is reduced,and even some major accidents occur.Permanent magnet eddy-current couplings can provide a new solution for the transmission problem.Using air gap between the drive shaft and a driven shaft instead of the physical connection structure.Transmit torque by using the coupling of magnetic field,which can effectively reduce the vibration,connection precision,fatigue damage,maintenance cost and increase the service life of the components in the permanent magnetic eddy-current couplings.In this paper,a permanent magnetic coupling with a power of 160 kW and 4motor drives is chosen as the research target.Main work:Firstly,by comparing the traditional coupling with the permanent magnet eddy-current couplings,the advantages of the permanent magnet eddy-current couplings are given.The disc type asynchronous permanent magnet eddy-current coupling is classified.The working characteristics of all kinds of coupling are introduced.Then the development and research of permanent magnetic eddy current coupling at home and abroad are introduced,and the problems facing this technology are summarized.Secondly,based on Maxwell’s equations,we establish partial differential equations under known boundary conditions.We solve the electromagnetic problems generated by the permanent magnet eddy-current couplings when we use the Maxwell equation to solve them.Thirdly,when the load is running compared with the no load time,the structure of the equivalent magnetic circuit is different,and the armature magnetomotive force is increased.This paper mainly analyzes the working state of the shaft when the load is running,and completes the derivation of the torque formula by using the magnetoresistance method.Fourthly,static magnetic field,the transient magnetic field and eddy current distribution in copper are analysis rely on Ansoft Maxwell.Fifthly,under the condition of guaranteeing a single variable,a simulation model of each target parameter is established in Ansoft Maxwell,and the relationship between the structural parameters with the output torque and axial force is analyzed.Sixthly,the permanent magnet can provide magnetomotive force for permanent magnet eddy-current couplings,but its heat resistance is poor,can not withstand high temperature,magnetic difference on high temperature,the working performance of the transmission efficiency is reduced,when subjected to high temperature or even exceed its Curie temperature(310~410℃),the the magnetic material can be greatly reduced,even irreversible demagnetization phenomenon.Analysis and finite element simulation of power loss,to ensure single variables,establish simulation model of the target parameters in Ansoft Maxwell,the analysis of the relations between the structure parameters and the copper loss and the maximum eddy current density,get the various structure parameters on the power loss of the law.Finally,high power permanent magnet eddy-current coupling if its structure can not meet the requirements of heat balance,the heat can not be distributed,it will cause permanent magnet eddy-current coupling temperature is too high,must consider the problem of heat dissipation in this case. |
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