Analytical Modeling And Design Optimization Of Permanent Magnent Eddy Current Coupler

Permanent magnet eddy current coupler can transmit torque between motor and driven load without mechanical contact along with many advantages such as isolated protection,ripple compensation,stationary dynamic process and adjustable speed,which is widely used as coupler,damper,brake and transmission in chemical industry,wind power,vehicles and other fields.However,the use of the permanent magnet eddy current coupler will bring speed drop and additional moment of inertia.To make a minimum influence on the original drive system,optimization design of the permanent magnet eddy current coupler is required to obtain high efficiency and low moment of inertia.The analytical modeling and design optimization of permanent magnet eddy current coupler are carried out,and the major works implemented in this dissertation are presented as follows:1)A steady-state model of permanent magnet eddy current coupler based on the equivalent circuit model is proposed.The copper plate is equivalent to a set of windings,and the flux linkage equation,voltage equation,and torque equation are established.The steady-state torque equation is obtained by solving these equations in steady-state condition,and the maximum torque of permanent magnet eddy current coupler is calculated from the static magnetic flux density,equivalent resistance,and equivalent inductance.Then,the problem that the existing steady-state analytical model cannot directly predict the maximum torque of the permanent magnet eddy current coupler through the geometrical parameters is solved.2)A transient model of the permanent magnet eddy current coupler based on the equivalent circuit model is proposed.By solving the flux linkage equation,and voltage equation in transient condition,the transient torque equation of permanent magnet eddy current coupler is obtained,and the dynamic performance of the permanent magnet eddy current coupler is studied combined with motion equation for rotating rigid bodies.Due to the reaction field of eddy current is accounted for by the equivalent inductance,the proposed transient model is valid for all slip speed values,which solves the problem that the existing transient model is only applicable to study the dynamic performance of the permanent magnet eddy current coupler at low slip speed.3)The particle swarm optimization algorithm is employed to optimal design the geometrical parameters of the permanent magnet eddy current coupler.A new objective function is proposed based on the equivalent circuit model of the permanent magnet eddy current coupler,and a constraint to the maximum torque of the permanent magnet eddy current coupler is added,so as to achieve high efficiency and low moment of inertia under the premise of matching the maximum torque with the driving motor.Then,the problem that the performance of the permanent magnet eddy current coupler cannot be improved fundamentally because of the excessive pursuit of improving the efficiency while ignoring the capacity of the coupler in the existing optimization design method of the permanent magnet eddy current coupler is solved.4)A design method of the permanent magnet eddy current coupler is developed to traversal search the geometrical parameters which can meet the constraint of maximum torque among the optimization ranges.The global optimum design scheme can be obtained by using the fitness function to evaluate the geometrical parameters and make satisfactory compromise between high efficiency and low moment of inertia.The problem in the existing optimization design method of the permanent magnet eddy current coupler that the intelligent optimization algorithm suffers from high randomicity and less ergodic is solved.