Analysis on Electromagnetic Force of Armature in Asynchronous Induction Coil Launcher

The armature is driven forward by induced electromagnetic force in asynchronous induction coil launcher, and the space-time characteristics of force on the armature affect the exit velocity and energy conversion efficiency. Affected by the driving current, velocity, displacement, and other factors, the electromagnetic force received by the armature has obvious nonlinear characteristics. In this article, simulation and analysis of the electromagnetic volume force (EVF) distribution of the armature under different initial positions in the transient model using the field-circuit coupling theory and finite element method are studied. The characteristics of the armature force during the propulsion process are summarized. The structure of armature is optimized according to the simulation results and experiments. It is found that depending on the initial position, the electromagnetic force distribution also varies. There is an optimal initial position that allows the armature to greatly reduce the value of peak force under the premise of ensuring exit velocity. During the period of propulsion, there are two concentrated areas of EVF on the armature. Because of the three-phase excitation, there are three peaks in each of the two areas. The distance between the peaks is about the width of single driving coil, which can be used to optimize the structure of armature.