Thrust force characteristic of a primary permanent magnet linear motor

To solve the problem that the thrust density and power factor of linear induction machines used for electromagnetic launch are too little, a primary permanent magnet linear motor (PPMLM) is proposed for electromagnetic launch. Firstly, the structure and operation principle of the PPMLM were given. Two-dimensional (2-D) finite element method (FEM) was used to investigate the static electromagnetic characteristics, and the characteristics of flux linkage, back electromotive force (EMF) and inductance were obtained. The co-energy method was implemented to derive the thrust force equation based on the static characteristics. The 2-D transient finite element method was employed to analyse the thrust force and the process of electromagnetic launch. The results of simulation are validated by experiment. Results of simulation and experiment demonstrate that the proposed motor has the advantage of minor cogging force, minor thrust force ripple and simple control strategy. This kind of PPMLM is well suitable for the application of electromagnetic launch.