Elastic oscillatory enhancement for electromagnetic energy harvesting

This study investigates the power generation performance of an elastic oscillating-enhanced electromagnetic energy harvester (EO-EMEH) subjected to external excitations. The device incorporates a spring and a soft magnetic core to induce oscillatory motion, thus creating a coupling relationship between the device’s natural oscillating frequency and the frequency of the input excitation. This coupling plays a critical role in determining power output. Experimental results reveal that as the frequency increases from 6 Hz to 12 Hz, the output power of the EO-EMEH initially increases, peaking at 10 Hz, and subsequently declines, with the peak consistently observed at 10 Hz across varying excitation amplitudes. To assess the efficiency of this coupling under optimal operating conditions, the electromagnetic force and magnetic attractive force curves are compared, revealing a maximum coupling efficiency of 77.86% at 10 Hz. Furthermore, the results demonstrate that output power increases with higher excitation amplitudes. To further analyze the power generation characteristics under varying experimental conditions, the induced electromotive force is quantified by calculating the envelope area of the relative velocity and magnetic distance curves. The envelope area is notably larger at 10 Hz compared to other frequencies. At an amplitude of 9 mm, the device attains a maximum open-circuit voltage of 3.832 V. These findings underscore the importance of well-coupled design in significantly enhancing energy harvesting performance, particularly at sub-resonant frequencies of environmental vibrations, highlighting its potential for practical implementation.