A Mutually Coupled Stabilization Coil Configuration for Electromagnetic Levitation Melting With Frequency Consideration

A conventional coil configuration of electromagnetic levitation melting (ELM) systems consists of a main coil connected with an anti-loop coil to provide the stability of the levitating workpiece. The reversed current in the anti-loop coil produces a reversed magnetic field that depreciates the total magnetic flux at the workpiece. In many cases, a smaller reversed current is sufficient to provide stabilization for a levitating workpiece. This paper proposes a mutually coupled stabilization coil in place of the anti-loop coil to improve the performance of ELM systems. The proposed stabilization coil system consists of two coils, an isolated upper coil, and a main levitation coil. The two coils are galvanically isolated while magnetically linked. The upper coil current is adjustable through the distance between the coils. This allows the upper coil to operate at a lower current than the main coil current but sufficient for the workpiece stabilization. Simulation results have confirmed that the magnetic flux density at the workpiece is higher in the isolation configuration than in the conventional anti-loop configuration. Experimental results have shown that the proposed system can improve the ELM system performance by reducing the heating time and power consumption of the melting process.