High Performance Hybrid Piezoelectric-Electromagnetic Energy Harvester for Scavenging Energy From Low-Frequency Vibration Excitation

There are many difficulties in the power supply of the wireless monitoring system for coal mine mechanical equipment. Vibration energy scavenging is a green and effective way to solve this problem considering the intense and continuous vibration of coal mechanical equipment. In this paper, a novel hybrid vibration energy harvester was designed and manufactured, which combined electromagnetic and piezoelectric transduction units. Vibration drives the two units to move in the vertical and horizontal directions to realize the energy conversion. The mathematic model was built to calculate and predict the performance while the simulation on the distribution of magnetic field and piezoelectricity potential provided the details in the design. Besides, the output signal generated by the vibration excitation of the electromagnetic unit, piezoelectric unit and the whole energy harvester were studied simultaneously. Moreover, the resonance frequency was tested to be 14Hz, and the optimum matching impedance was measured to be 1k Omega and 10k Omega with the parallel and series connection of PH and EH, respectively. The maximum output power of the HPEH with the parallel connection pattern can reach 80.10mW at the acceleration of 2g. In the application experiment, the HPEH can facilely light up 120 LEDs and supply stable power for the electronics and sensors.