Air-gap magnetic field design optimization for U-shaped ironless permanent magnet linear synchronous motors

A U-shaped ironless permanent magnet linear synchronous motor, made by our group, is studied in this paper. The magnetic flux density stabilization is a primary problem, as the air-gap magnetic field with normal component of flux density of longitudinal sine and latitudinal uniformity is required for many precise positioning systems. We proposed a design optimization to improve the magnetic flux density and reduce magnet volume by defining a flexible objective function, where a genetic algorithm was used to find the optimal motor dimensions. The design optimization was verified by a layered finite element analysis, which could lower the complexity of the magnetic field analysis. And experimental results of the prototype were provided to illustrate the effectiveness of the proposed idea.