ELECTROMAGNETIC INDUCTION IN A SLOTTED TOROID CORE USING A MOVING MAGNET AND WIRE WINDING

Abstract

The study of electromagnetic induction in nontraditional core geometries has gained considerable attention due to its potential applications in compact energy harvesting systems. This paper presents an analytical and conceptual investigation into the generation of electric current using a slotted toroidal core, where a permanent magnet moves linearly through the air gap of the toroid, and a copper coil is wound around the remaining closed section of the core.

Unlike standard toroidal transformers that exhibit negligible external magnetic field, introducing a slot creates a discontinuity in magnetic flux, enabling flux variation through the coil during magnet motion. This asymmetry is exploited to induce electromotive force (EMF) via Faraday’s law. The paper develops a theoretical model based on Maxwell’s equations and magnetic circuit analogies, deriving expressions for magnetic flux density, induced voltage, and current flow. The influence of toroid dimensions, core permeability, magnet strength, coil resistance, and relative motion is mathematically characterized.

Practical considerations such as eddy current suppression, energy conversion efficiency, and mechanical constraints are discussed, along with potential use cases in kinetic energy harvesting and compact linear actuators. The results demonstrate that a properly optimized slotted toroid configuration can serve as a basis for simple yet effective electromagnetic generation systems, particularly in constrained or portable applications.