Magnetic coupling resonance wireless power transfer technology has attracted worldwide attention in recent years due to its mid-range, non-radiative, and high-efficiency power transfer. However, in regard to its practical applications, there are still some issues that need to be considered and studied with respect to coil design, such as coil structure, and parasitic parameter extraction. This paper investigated the characteristics of magnetic coupling resonance wireless power transfer systems with different coil structures, including circular coils and rectangular coils arranged in parallel. We calculated the magnetic field distributions and mutual inductances by subdividing the receiving coils and computing the magnetic flux density of each subdivision. The proposed analysis was validated by means of the finite element analysis and the experimental results. We investigated the effects of the coil's structure, and topological structures, on the power transfer efficiency. The results demonstrate that using circular coils in parallel is more advantageous than using rectangular coils.
A new type of multipole field electromagnetic launcher is designed in this paper, which has two parallel layers of multipole structure, and there is a 30-degree relative torsion angle between the inner and the outer one. The armature is designed as a complete and symmetrical hollow cylindrical metal sleeve with no slots. Owing to the superposition of the magnetic fields generated by the two layers, this novel structure can make the magnetic field density and eddy current distribution on the armature unbalanced, which generates an axial force and torque simultaneously. Simulations were conducted, and the magnetic field and the eddy current distribution were analyzed. The simulations indicate that this double-layer multipole field electromagnetic launcher achieves a rotational motion and a higher linear speed than that of single-layer structure. Experiments were performed and the results verified the correctness of the simulations. Due to its rotational performance, this configuration provides an approach to obtain gyroscopic stabilization for projectiles. It creates condition for multi-stage and combined mode applications because the armature does not need to be processed particularly to meet special requirements. INDEX TERMS Double-layer multipole field electromagnetic launcher, eddy current distribution, magnetic force and torque, rotational motion.
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