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To better harvest the kinetic energy of the human and broaden the energy harvest frequency band, a nonlinear piezo-electromagnetic composite human energy harvester (NPE-HEH) is proposed. A magnetic repulsion force between the two groups of magnets makes the energy harvester nonlinear. The excitation experiment and the actual experiment of the human are carried out for the harvester. The excitation experiment results show that there is an optimal resistance value of the harvester to maximize the output power value. When the excitation acceleration is 0.4 g and the excitation frequency is 9 Hz, the output voltage value and the output power of the electromagnetic part of the energy harvester are 0.86 V and 2.47 mW respectively, and the output performance is excellent. When the energy harvester is installed in a backpack with a moving speed of 9 km/h, it can generate 0.7 mW of power. When the energy harvester is placed on the leg, the output performance is good and the output power can reach 1.3 mW. The energy harvester can efficiently harvest energy at low frequencies. This harvester is efficient at low frequencies, compact in size, and easy to carry, making it highly suitable for human vibration energy harvesting applications. [ABSTRACT FROM AUTHOR]

This paper proposes a Dual-Cylinder Piezoelectric Energy Harvester (DC-PEH). The cylinders generate vortex-induced vibration under the action of wind, driving the cantilever beam to deform. During the vibration process, the cantilever beam produces two types of bending modes, namely U-shaped vibration and S-shaped vibration. According to the experimental results, as the wind speed increases, the output power of the DC-PEH first increases and then decreases. When the diameter of the cylinders at both ends of the DC-PEH is 36 mm and the wind speed is 4.3 m/s, the output power can reach 7.812 mW. [ABSTRACT FROM AUTHOR]

This paper presents a magnetically coupling bending-torsion piezoelectric energy harvester based on vortex-induced vibration from low-speed wind. The theoretical model of the energy harvester was formulated and validated by wind tunnel experiments. Numerical and experimental results showed that the power output and bandwidth of the proposed harvester are improved about 180% and 230% respectively compared with the nonmagnetic coupling harvester. Furthermore, the effects of cylinder, piezoelectric layer, load resistance, and magnetic nonlinear parameters on the harvester were investigated based on the distributed parameter model. The results showed that the length of cylinder hardly affect output power, but the diameter of cylinder presented complicated influences. The width of piezoelectric beam was negatively correlated with the torsion angle. With increasing the length of piezoelectric layer, an optimal wind velocity and load resistance can be obtained for the maximum output power. With decreasing of the distance between two magnets, the resonant bandwidth, the optimal power output, and torsion angle can be enhanced, respectively. Besides, the magnetic potential energy increased owing to the magnetically coupling, which led to the improvement of onset speed for the energy harvester. This study provides a guideline on improving the performance of bending-torsion vibration piezoelectric energy harvester. [ABSTRACT FROM AUTHOR]

AbstractThis article proposes a low-frequency and efficient tension-like nonlinear piezoelectric energy harvester, which increases the harvesting performance of the harvester by swinging the support frame. Firstly, design the structure of the harvester and draw a physical model. Secondly, finite element models are used to simulate and analyze the structure’s dynamic characteristics. Finally, make an experimental prototype of the harvester and explore the power generation characteristics of the device through experiments. The results indicate that the harvester has two natural frequencies under low-frequency conditions. The energy harvester has the optimal external resistance to achieve peak output power. The greater the excitation acceleration, the greater the total output power value of the energy harvester. When the mass of the mass block is 3.7 g and the excitation acceleration is 0.4 g, the total output power value of the energy harvester is 3.88 mW, and the harvesting frequency band is wide, indicating excellent output performance of the harvester. The experimental results of the energy harvester device are consistent with the simulation results, fully verifying the correctness of the experiment and simulation. This piezoelectric energy harvester can efficiently harvest vibration energy at low frequencies, providing a good prospect for supplying power to microelectronic devices. [ABSTRACT FROM AUTHOR]