Application of the Multiple Population Genetic Algorithm in Optimum Design of Air-core Permanent Magnet Linear Synchronous Motors

In order to achieve high thrust density,low thrust ripple and low copper loss simultaneously of long stroke linear motors applied to step and scan projection lithography,a multiobjective optimization design method of the air-core permanent magnet linear synchronous motor with ring windings based on the multiple population genetic algorithm was presented.On the basis of the magnetic field analysis model,the analytical formulae of key parameters was deduced.By using sizes of permanent magnets and ring windings as variables and taking thrust per volume,motor constant and thrust ripple as optimization goals,we proposed a multiobjective optimization function with weight coefficients,and applied the multiple population genetic algorithm with strong searching ability and fast convergence speed to optimizing structure and sizes of the motor.The results confirm that motor optimization design results by the multiple population genetic algorithm and the design goal have a good consistency for different weight coefficients.3D finite element analysis(3D-FEA) and experimental results prove the validity and feasibility of the proposed method.