![]() The two beams are placed face to face with a fixed space between them. proposed an impact-rope hybrid mechanism: the energy harvester comprises a high-frequency generating beam attached to a piezoelectric layer and a low-frequency driving beam. proposed a frequency up-conversion piezoelectric vibration energy harvester driven by mechanical impact, employing a horizontally extended tip mass of a low-frequency driving beam to impact repeatedly on the free ends of two high-frequency unimorph-generating beams at the same time. The contact method is realized by mechanical contact. ![]() ![]() When the FUC energy harvester is applied in a low-frequency environment, it can achieve a high-frequency vibration close to its natural frequency and improve the output power. The frequency up-conversion technology can transform the low-frequency vibration in the environment into the high-frequency vibration needed by the energy harvester. Various frequency up-conversion (FUC) methods have been used, which can be divided into contact and non-contact methods. In order to improve the output power and bandwidth of the energy harvester in the low-frequency environment, a frequency up-conversion energy harvester has been proposed. Hence, the traditional piezoelectric structure greatly limits the effectiveness of the piezoelectric energy harvester in the low-frequency vibration environment. The reason for this power reduction is that low frequencies will increase internal resistance. Moreover, if the frequency is simply reduced, the power is limited even if the resonant state is reached. This is mainly because the excitation frequency does not match the natural frequency of the energy harvester. When a traditional piezoelectric energy harvester is applied in a low-frequency environment, the output power is too low to operate stably with electrical appliances. Vibration in the environment is mostly of low frequency (0~30 Hz). Īlthough considerable progress has been made in the research of piezoelectric energy harvesters over the past several decades, the traditional piezoelectric structure has a high natural frequency. The piezoelectric energy harvester has the advantages of high output voltage, simple structure, easy integration, etc. ![]() Kinetic harvesters mainly include the piezoelectric energy harvester, electromagnetic energy harvester, electrostatic energy harvester, friction energy harvester and multi-mode composite energy harvester. Because vibrations have a high energy density, using vibration energy as the power source of energy harvesters is gaining favor. With the development of electronic technology, the energy demand of micro-power devices is decreasing, and it is possible to harvest energy from the environment to power these devices. The structure has the potential to power wireless sensor nodes or to be used as a small portable vibration storage device, especially suitable for the monitoring of the environment related to human movement. The tuning fork frequency up-conversion energy harvester causes the humidity sensor to work stably. At the resonant frequency of 7.3 Hz under 0.7 g acceleration, the peak voltage is 41.8 V and the peak power is 8.74 mW. This structure provides the energy harvester with excellent output power in a low-frequency vibration environment. Theoretical and experimental results show that the tuning fork frequency up-conversion energy harvester has excellent performance. The low-frequency energy collection and the high-frequency energy conversion can be achieved simultaneously. The in-phase vibration mode is used to sense the environment vibration, and the anti-phase vibration mode is used for energy conversion and power generation. The structure has an in-phase vibration mode and an anti-phase vibration mode. In this paper, a novel tuning fork structure for self-frequency up-conversion is proposed.
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