Modeling and comprehensive analysis of parameters on a compact pendulum-based electromagnetic energy harvester

Pendulum-based electromagnetic energy harvesters (PEEHs) convert human motion, particularly walking, into electrical power through intricate electromechanical coupling to power Internet of Things devices. Despite their potential, most studies represent PEEHs using equivalent or simplified models, which often limit dynamic analysis or result in significant computational errors. To address this limitation, we develop an accurate electromechanical coupling model for a compact PEEH incorporating a compound planetary gear train. The magnetic field is evaluated using the magnetic scalar potential method, while system dynamics are formulated via the Euler–Lagrange approach. Magnetic field predictions are validated against finite element simulations in COMSOL. Under geometric constraints, extensive parameter sweeps—including swing frequency, swing amplitude, gear ratio, load resistance, and the pendulum-to-rotor moment of inertia ratio—are performed through numerical simulations. Experimental studies further validate the numerical results. Both simulation and experimental results demonstrate that PEEH performance converges to a local optimum under fixed conditions, and that increasing the moment of inertia ratio enhances performance under parameter optimization. The developed prototype achieves a maximum output power of 18.70 mW and a normalized power density of 29.92 W/(m³·Hz·°), confirming the proposed model's efficacy to guide the design of high-performance energy harvesters.