Design and Research on a Nonlinear 2DOF Electromagnetic Energy Harvester With Velocity Amplification

In order to power the microelectronic devices of the Internet of Things in the low-frequency broadband vibration environment, a novel nonlinear 2DOF electromagnetic energy harvester was proposed based on the magnetic levitation structure and velocity amplification mechanism. The electromechanical coupling model was established and numerically simulated to analyze the generating characteristics. A prototype was fabricated and tested to verify the theoretical model. The influences of the key parameters, including the gap between the suspended magnet and the lower spring, excitation acceleration, spring stiffness, mass of copper cylinder, on the generating characteristics were studied. When it was subjected to a harmonic excitation with acceleration amplitude of 0.8g, the measured open-circuit voltage reached peaks of 3.13 V at 8 Hz and 2.93 V at 13.5 Hz, respectively. The optimal output power at 8 Hz was 10.18 mW with the matched load resistance of 250~Ω. Both the experimental and theoretical results demonstrated that this novel electromagnetic energy harvester had obvious advantages in increasing the output power and widening the bandwidth.