A Large Linear Interior Permanent Magnet Motor for Electromagnetic Launcher

In this paper, a magnetic analysis of large linear motors with long primary and short interior permanent magnet (PM) secondary is presented. The calculations are carried out using a finite-element method, taking into account the secondary motion and saturation in iron parts. Reluctance force could be increased using interior PM secondary. The thrust force oscillations are evaluated to obtain minimum force ripple. Furthermore, a magnet demagnetization analysis is presented to evaluate the magnet demagnetization risk under loading. Reduction in the magnet volume is considered for cheaper and simpler secondary structure.