| The radial flux permanent magnet eddy current coupler(PMEC)is a kind of transmission equipment which relies on the interaction between the magnetic field caused by permanent magnet array and the magnetic field formed by the induced eddy current in the conductor ring.Since the radial flux PMEC relies on non-contact magnetic drive,it has many characteristics compared with the traditional coupler,so it is necessary to understand its characteristics and performance when designing and using the radial flux PMEC.The main parameter to assess the performance of the radial flux PMEC is the torque density,which described the ability of the transmission torque under the same structure size and the slip of the inner and outer rotors.Generally,the higher the torque density is,the better the coupler performance will be.In this paper,the performance of torque transmission and application characteristics of the radial flux PMEC are studied by means of theoretical analysis and finite element simulation.Based on the two-dimensional layer theory and the method of separating variables,the mechano-magnetic-electric-mechanical process of energy conversion in the transmission process of the radial flux PMEC is deduced.Based on the method of equivalent magnetic circuit and the law of ampere force,the magnetic field expression and the torque expression of the permanent magnet array of the radial flux PMEC are obtained.It is considered that the magnetic field parameter(B2)avg at the center line of the conductor ring is an important parameter to measure the magnetic field performance,and it is proportional to the torque density of the coupling.ANSYS Electronicdesktop finite element simulation software was used to analyze the structural parameters and dynamic parameters affecting the torque characteristics and performance of the coupling,it is useful to the structure design of the radial flux PMEC.By comparing and analyzing 12 kinds of permanent magnet arrays in common use,it is concluded that the traditional 2-parts Halbach arrangement cannot improve the magnetic field performance of the permanent magnet array of the radial flux PMEC,and the performance of the permanent magnet array using the alternant arranged sector permanent magnet with parallel magnetizing is better.Based on the application condition,a motor – a radial flux PMEC-a square load analysis model is established,and the energy saving performance,transmission performance,start performance,load performance and load torque wave response performance of the radial flux PMEC are analyzed.Based on the energy balance equation,the power loss model of the radial flux PMEC is established.Using ANSYS Electronicdesktop and ANSYS Workbench Steady-State Thermal,the power loss and Thermal field of radial flux PMEC in the overload and the designed working point downward adjustment of are analyzed,according to the results,the radial flux PMEC at the designed working point downward adjustment,heating power is not change much,special cooling is unnecessary.In order to rise the torque density and improve the concentration of heating area of the coupling at low engagement,the permanent magnet array and the conductor ring as the main working parts of the coupling can be improved.The magnetic field performance of the permanent magnet array can be effectively improved by using the unequal 2-parts Halbach arrangement.According to the finite element simulation calculation,compared with the traditional 12 pole alternant arranged permanent magnet array,with the parallel magnetizing,(B2)avg is improved by 8.94%,with radially magnetizing,(B2)avg improved by 11.73%.The conductor ring was improved by the method of axial slotting.The finite element calculation result show that the torque density of the radial flux PMEC increased significantly by using slotting on conductor ring,comparing with no slot model,the average torque of model with 24 slotting on conductor ring rise by 24.56%,with 36 slotting on conductor rise by 36.97%,and the uneven distribution of heat under low engagement was weakened,but the torque fluctuation appears.By the method of increasing the number of slots,changing the number of slots to odd number,with oblique slotting and changing the proportion of slot width,the torque fluctuation can be weakened. |
