An Impact-Based Frequency Up-Converting Hybrid Vibration Energy Harvester for Low Frequency Application

In this paper, a novel impact-based frequency up-converting hybrid energy harvester (FUCHEH) was proposed. It consisted of a piezoelectric cantilever beam and a driving beam with a magnetic tip mass. A solenoid coil was attached at the end of the piezoelectric beam. This innovative configuration amplified the relative motion velocity between magnet and coil, resulting in an enhancement of the induced electromotive force in the coil. An electromechanical coupling model was developed and a numerical simulation was performed to study the principle of impact-based frequency up-converting. A prototype was fabricated and experimentally tested. The time-domain and frequency-domain analyses were performed. Fast Fourier transform (FFT) analysis verified that fundamental frequencies and coupled vibration frequency contributes most of the output voltage. The measured maximum output power was 769.13 mu Wat a frequency of 13 Hz and an acceleration amplitude of 1 m/s(2), which was 3249.4%-and 100.6%-times larger than that of the frequency up-converting piezoelectric energy harvesters (FUCPEH) and frequency up-converting electromagnetic energy harvester (FUCEMEH), respectively. The root mean square (RMS) voltage of the piezoelectric energy harvester subsystem (0.919 V) was more than 16 times of that of the stand-alone PEH (0.055 V). This paper provided a new scheme to improve generating performance of the vibration energy harvester with high resonant frequency working in the low-frequency vibration environment.