Investigation of the nonlinear electromagnetic energy harvesters from hand shaking

This paper presents the design, modeling, and optimization of an electromagnetic energy harvesting (EMEH) device with various tube length and winding coil width. The nonlinear magnetic-spring configuration is employed for generating sufficient power from hand shaking of irregular and low-frequency vibrations. Based on the modeling and simulation, longer tube length of the EMEH device results in lower resonant frequency and stronger nonlinearity of the system and thus is more efficient for low-frequency harvesting. From the hand shaking test, it is found that a longer tube length and a shorter winding coil width could induce a higher power generation. The optimized device of tube length of 66 mm and winding coil width of 10 mm has achieved maximum power outputs of 568.66 μW at the hand shaking acceleration of 1 g and frequency of 6.7 Hz, which corresponds to the power density of 90.67μW/ cm³. Further improvement of the device has been achieved by increasing the coil length to 40 m. This device provides maximum power outputs of 825.36μW at the hand shaking acceleration of 1.56 g and frequency of 6.7 Hz. This paper demonstrates a feasible design of nonlinear EMEH device with impressive output performance from hand shaking.