| Drum-type solid asynchronous magnetic coupler(DSAMC)is a new type of speed-control transmission device,which realizes the transmission of force and torque through electromagnetic induction.As a transmission device,the magnetic coupler has advantages that traditional couplers cannot have,such as non-contact transmission,soft start/stop,low neutrality,and good sealing performance.As a speed-control device,the cheaper magnetic coupler can replace the frequency converter,particularly in harsh environments.At present,the magnetic coupler has been applied in many industries,such as mining,power,steel,chemical,petroleum and other industries.In this paper,the research on DSAMC is mainly focused on as follow:Firstly,the electromagnetic torque formula of DSAMC is deduced.The equivalent magnetic circuit model is established based on analysis of the structure and the magnetic circuit of the magnetic coupler.The magnetomotive force and various parts reluctance are calculated in the equivalent magnetic circuit model.The static air gap flux density is deduced combined with Kirchhoff's current law and current loop method.The static air gap flux density is brought into the torque formula,and the 3-D correction coefficient is introduced to get the final calculation formula of DSAMC.Furtherly,Matlab is used to calculate the torque under different slips and the torque under different relative positions of the permanent magnet rotor and the conductor rotor.Secondly,the finite element analysis is used to analyse the air gap magnetic field and the transmission performance of DSAMC.A 3-D model of the magnetic coupler is built by Magnet to simulate and analyze the distribution of 3-D transient magnetic field.The magnetic flux density distribution of overall magnetic coupler and the magnetic flux density distribution in circumferential,radial and axial directions of the copper are obtained.And the distribution of the radial air-gap flux density at different axial positions is obtained.The current density distribution and 3-D end effect of the magnetic coupler are simulated and analyzed.The induced current of the copper and theinfluence of the distance of the permanent magnet rotor deviating from the axial center position of the conductor rotor on the 3-D end effect are obtained.The influence of slips and relative positions of the permanent magnet rotor and the conductor rotor on torque are simulated and analyzed,and the theoretical values of torque is compared with the simulated values to verify the correctness of the theoretical analysis.Thirdly,the finite element analysis is used to analyse variable load start performance of DSAMC.The mathematical model of the start process of the transmission system of DSAMC is established,and the kinetic equations is deduced.The load characteristic curve of variable torque load and the mechanical characteristic curve of magnetic coupler are analyzed.The finite element analysis is used to analyse the fixed start and the mobile start of the system under different conditions.Variation rules of speeds and torque in the start process are studied.Lastly,the comparative analysis between the fixed start and the mobile start can obtain that the fixed start reaches a stable operation in a short time,but there is a large torque fluctuations in start process.The mobile start can effectively avoid the fluctuations,but the longer it takes to reach a stable operation.Finally,test platforms for constant load and variable load are built to verify the validity of the torque calculation formula and the finite element analysis.The test platform for constant load is used to measure the relationship between torque and slips and relative positions of the permanent magnet rotor and the conductor rotor.The test platform for variable load is used to measure the output speeds and torque in different input speeds and in different relative positions when the magnetic coupler is driving the fan load.The calculated values,simulated values,and measured values have better consistency. |
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