Research On Working Performance Of Magnet Rotaion Speed-regulating Magnetic Coupler In Electromechanical-magnetic Coupler System

The magnet rotation speed-adjusting magnetic coupler(MRSMC),as a new type of non-contact transmission device,inherits the characteristics of the traditional speedadjusting magnetic coupler with reliable structure,low cost,stable operation,high efficiency and energy saving.With its unique speed regulation method of rotating unipolar permanent magnets,it performs better in terms of speed regulation range and energy saving.In this paper,the theoretical,simulation and experimental methods are used to study the working performance of the magnetic rotating speed-adjustable magnetic coupler in the electromechanical-magnetic coupling system(EMCS).The details are as follows:Firstly,the vector magnetic potential is introduced to conduct magnetic field analysis and electromagnetic torque expression deduction of the MRSMC.The magnetic flux density of each layer is analyzed by dividing the theoretical layer model of the magnetic coupler.According to the boundary conditions,the general solution of the scalar magnetic potential of each layer is calculated to obtain the axial and circumferential components of the air gap magnetic density.And the electromagnetic torque expression considering the three-dimensional effect is derived from this.The three-dimensional air gap magnetic density distribution is calculated by numerical analysis software,and the air gap magnetic density waveforms of different air gap positions are obtained for comparative analysis.It is found that the farther away from the permanent magnet layer,the smaller the fluctuation of the air gap magnetic density amplitude.Secondly,the steady-state air gap magnetic field,electromagnetic torque,and axial force of the coupler are simulated and analyzed.The steady-state axial and circumferential air gap magnetic density,electromagnetic torque,and axial force amplitude variation rules under different air gap thicknesses and different magnet rotation angles are obtained.Using the simulation results and the characteristics of the motor and load,the steady-state speed equation of the EMCS is constructed.The steady-state speed under different constant torques,variable torque and constant power load,as well as the steady-state speed under different air gap thicknesses and different magnet rotation angles are solved.The change rules of steady-state input speed and output speed under different load conditions and different speed regulation states are obtained.The change law of steady-state speed under different conditions is analyzed.Thirdly,the dynamic response model of the EMCS is constructed,and the input and output torque,acceleration,and speed of the starting and speed regulation process under different loads are changed with time through numerical analysis software.Through comparative analysis,it is found that the magnetic coupler has two starting states.The changes of torque,acceleration and speed with time in the two states are different.The distinguishing condition is whether the rotation speed difference is always kept below the critical rotation speed difference during startup.When adjusting the air gap thickness and the rotation angle of the magnet,the adjustment from large to small is compared with that from small to large,and it is found that the former takes less time to reach steady state,but the amplitude of torque,acceleration and speed amplitude fluctuates more.In addition,the soft start characteristics and overload protection characteristics of the coupler are analyzed.Finally,the transmission performance,speed regulation performance and starting performance of the magnetic coupler in the EMCS are tested.The transmission performance test verifies the accuracy of the electromagnetic torque formula at low torque,and verifies that the electromagnetic torque of the coupler is indirectly related to the input speed and directly related to the speed difference.The speed regulation performance test verifies that when the load is a variable torque load,the steady state input speed of the magnetic coupler will increase slightly with the increase of the air gap thickness.The start-up performance test compares the start-up dynamic characteristics when the air gap thicknesses are 6mm and 14 mm,and verifies that the magnetic coupler has two start-up states because of the difference in the speed difference during startup.