Secondary Constructions of Linear Synchronous Motor with Divided Permanent Magnets.

Differently from the general linear synchronous motor (LSM), the permanent magnet type linear synchronous motor (PM-LSM) hardly has field windings. Thus, the reduction of hunting oscillations much depends on damper windings. In this paper, we propose novel constructions of PM-LSM that is obtained by dividing magnets and arranging them suitably. With this method, it is possible not only to provide spaces for damper windings but also to eliminate space harmonics of magnetic fields. In this paper, we research into secondary constructions by theoretical analyses and the three-dimensional finite element analysis. To conform the validity of analyses, we also compare it with experimental data. The follows are confirmed. (1) We derive arrangements of magnets that eliminate four kinds of harmonics (5, 7, 11, 13), and we propose a novel arrangement that has advantages from the productive point of view using same width of magnets. (2) Concerning with preferable arrangements of damper windings, distributed windings are more effective in stabilizing operations than concentrated windings, and those arranged at the same intervals are more effective than arranged unequally. We also confirmed the improvement of characteristics with solid plates under magnet parts.