An Electromagnetic-Piezoelectric Hybrid Harvester Based on Magnetic Circuit Switch for Vibration Energy Harvesting

Energy harvesting technologies are contributing to the development of the Internet of Things. These techniques can provide continuous, energy-efficient and environmentally friendly power supplies and reduce manual maintenance requirements, and thus have strong prospects for sensing and monitoring applications, particularly in certain harsh working environments. The proposed electromagnetic-piezoelectric hybrid harvester contains both electromagnetic generator (EMG) and piezoelectric generator (PEG). Through vibration of the cantilever beam, the magnetic circuit in the soft-magnetic material is both connected and disconnected, and this can cause the magnetic flux in the coil to change dramatically, resulting in induction of a large voltage in the coil. This paper illustrates the feasibility and the optimal characteristics of the proposed hybrid harvester using theoretical verification and simulations, and demonstrates the factors that affect the power generation effect through testing. The study found that the maximum open-circuit voltages of the EMG and the PEG are 16 V and 42 V and the maximum peak powers of the EMG and the PEG reach 20 mW and 35 mW, respectively. The proposed energy harvester offers advantages in terms of both peak voltage and peak power, and provides a new method and concept for the vibration energy harvesting field.