Study On Magnetic Field Distribution And Work Performance Of Speed Adjustable Solid Disc Asynchronous Magnetic Coupler

Speed-adjustable solid disk asynchronous magnetic coupler(SASDAMC)is based on the principle of electromagnetic induction.This is a new type of transmission device which realizes medium-free transferring torque.The advantages of the device are safer,more energy efficiency,less installation precision requirement,overload protection,reducing equipment failure frequency and many more.Nowadays this technology is being widely used in electricity,water utilization,chemical industry,agriculture and other industries.Thus,the study of SASDAMC has not only high scientific value in academics,but also high practical value in engineering.This paper mainly studies the SASDAMC as the followings:Firstly,the vector magnetic position method using higher harmonics is applied to calculate air gap magnetic field and electromagnetic torque of SASDAMC.Combining the analysis result of respective layers of the magnetic vector potential in theoretical model layers and the boundary conditions,equations are established,which can be used to calculate the magnetic vector potential of all respective layers of the theoretical model layer.The air gap magnetic density of magnetic coupler can be expressed by magnetic vector potential.The induction current density in copper layer can be calculated by air gap magnetic density.The final electromagnetic torque can be calculated with three-dimensional correction factor.The air gap magnetic density formula is introduced into the numerical analysis software for programming,and the 1st,3rd,and 5th harmonic waveforms are obtained,then the waveform and attenuation trend are analyzed.Moreover,the waveform of the air gap electromagnetic density is obtained by superimposing the 1st,3rd,and 5th harmonics by the method of harmonic superposition.Secondly,the nonlinear finite element analysis method which the higher harmonics is introduced into is used to simulate the distribution of static magnetic field,transient magnetic field and induced magnetic field of SASDAMC.Through simulation,the three-dimensional waveforms of the axial and circumferential static magnetic fields at the different gap positions on the cylinder of the average radius and at the different radii of the intermediate air gap are obtained,respectively,and the attenuation speeds of the 1st,3rd,and 5th harmonic amplitudes in the air gap magnetic field are verified.Through the analysis of transient magnetic field under constant torque load condition,the law is obtained: the larger the load,the smaller the axial air gap magnetic density is,the larger the magnetic density of the circumferential air gap is.By analyzing the transient magnetic field under variable torque load conditions,the larger the variable load coefficient,the smaller the axial air gap magnetic density is,and the larger the circumferential air gap magnetic density is.Moreover,the air gap magnetic density amplitude and the variable load coefficient have a linear relationship within a certain range.According to the spatial waveform distribution of the induced magnetic field and the original magnetic field,the larger the difference of the rotational speed,the more the induced magnetic field air gap magnetic density waveform gradually shifts toward the original magnetic field and the air gap magnetic density amplitude increases first and then decreases slightly and finally reaches a limit.Thirdly,the transmission performance of SASDAMC is simulated.By setting the rotational speed of the moving body,the electromagnetic torque under different speed difference is obtained.According to the output speed and electromagnetic torque,the mechanical characteristic curve is obtained,and the speed regulation performance and starting characteristics of the coupler are analyzed through the mechanical characteristic curve.Then the rule is obtained that regularity of the range of the common characteristic is continuously reduced as the thickness of the air gap increases.According to the influence of different input speeds on the mechanical characteristic curve,a method for simultaneously adjusting the input speed and air gap thickness to obtain the ideal speed range under variable torque load conditions is proposed.By analyzing the relationship between the thickness of the air gap,the difference between the rotational speed and the axial force,the law that the range of the axial force changes decreases with the increase of the air gap,and the difference of the rotational speed at the zero point of the axial force is almost constant.By analyzing the relationship between the rotational speed difference and the eddy current loss under different air gap thicknesses,the smaller the difference of the rotational speed,the smaller the influence of the air gap thickness on the eddy current loss is.Finally,static air gap magnetic field and transmission performance of SASDAMC are tested by establishing static air gap magnetic field measurement experimental platform and work performance test platform.The static air gap magnetic field distribution on the circumference of different air gaps on the circumference of the average radius of the magnetic coupler and the circumference of the different radius of the intermediate air gap are respectively measured by the static air gap magnetic field measurement experimental platform.The mechanical characteristic curve of the magnetic coupler is tested by the working performance experimental platform,and the regularity of the range of the common characteristic phase with the thickness of the air gap is verified.The influence of the input speed on the mechanical characteristic curve is verified by testing the electromagnetic torque corresponding to different input speeds when the rotational speed difference is constant.The speed regulation performance under variable torque load conditions is tested and the influence of input speed on the speed regulation range is verified.The test values agree well with the calculated and simulated values.