Low-bandwidth Vibration Energy Harvester Applied To Watercraft

Wave energy is a renewable energy that has huge reserves and has not been fully developed and utilized.Therefore,making full use of wave energy is of great significance to alleviating the energy crisis and reducing environmental pollution.However,the low-frequency,broadband,random,multi-directional characteristics of wave energy,the corrosive environment of seawater,and extreme weather conditions have brought huge challenges to the development and utilization of wave energy.This paper proposes a multi-modal vibration energy harvesting device for wave energy harvesting.The device redesigned the typical cantilever beam structure and adopted a cross beam structure with multi-directional vibration energy collection capabilities and multi-modal characteristics to achieve multi-directional broadband vibration energy collection.The triboelectric device based on liquid metal is used to replace the traditional counterweight design,and without increasing the complexity of the device structure,the power generation efficiency of the multi-modal vibration energy harvester is improved.Unlike traditional piezoelectric,electromagnetic and other vibration energy harvesting technologies,the triboelectric nanogenerator still has a better response at low frequencies.This paper firstly analyzes the working principle of the friction nanogenerator from the perspective of displacement current,and establishes a capacitance model for the independent metal layer friction nanogenerator used in this paper,and analyzes the charge distribution and transfer of the liquid metal triboelectric device and the V-Q-x relationship And load output characteristics are analyzed.Based on the characteristics of liquid metal,liquid metal triboelectric devices have greater energy density than traditional triboelectric nanogenerators.In addition,the fluidity of liquid metal also makes the device better adapted to the collection of wave energy.The cross beam structure is equivalent to the coupling of a vertical cantilever beam and two horizontal branch cantilever beams.This coupling not only makes the device have a better response under environmental excitations in different directions,but also gives the device multi-modal characteristics,namely There are multiple resonance frequencies within a certain bandwidth,which greatly expands the effective working bandwidth of the device and makes the device more suitable for wave energy collection.In this paper,the cross beam structure is calculated and analyzed in detail.First,the cross beam structure at different branch beam installation positions is analyzed by finite element simulation,and the corresponding resonance frequency distribution under various positions is analyzed,and the most suitable Installation location of the branch beam for wave energy haivesting.Furthermore,the finite element simulation analysis of the cross beam structure of different sizes was carried out to determine the appropriate size.This paper verifies the multi-modal characteristics of the multi-modal vibration energy harvesting device and the multi-directional vibration energy harvesting energy through the comparative experiment of setting up a single-mode vibration energy harvesting device(single beam device).Compared with the single-mode vibration energy harvesting device,the multi-mode vibration energy harvesting device expands the effective working bandwidth by 6.25 times and the peak open circuit voltage by 6.9 times.In terms of output capacity,the multi-mode vibration energy harvesting device can rush a 10μF capacitance to 1.49V in 65s,which is 11.4 times higher than that of the single-mode vibration energy harvesting device.In the environmental simulation experiment,under waves,the multi-modal vibration energy harvesting device can light up 24 LED lights at the same time.In addition,the multi-modal vibration energy harvesting device can haivest the vibration energy during the movement of the watercraft,and the 10μF capacitor can be charged to 4.76V within 5 minutes,which further proves the device’s potential to collect wave energy.