Study On Water Wave Energy Harvester For Marine Movable Platform

The deep ocean is an important sea area for national strategic defense.It contains important resources for sustainable development in the future and is also an important regulator of the global climate system.The marine movable platform is an abandoned flux drift buoy used for all-weather and all-weather ocean observation.It plays an important role in the development of marine resources,marine disaster forecasting,etc.It is of great significance to national economy,people's livelihood and national security.The marine movable platform cannot carry the power required for its long-term work by simply carrying the battery pack and reducing power consumption.Obtaining energy from the marine environment is an important way to extend the working life of the platform.Wave energy is the most direct and reliable energy source that can be obtained by the marine movable platform due to its advantages of being free from the influence of natural conditions such as environmental temperature,time and place,and seasonal climate.The collection and use of wave energy provides conditions for long-term automation of marine equipment and is an important development direction for energy supply of marine equipment.Wave motion in the marine environment is random and complex with extremely low frequencies.Under this kind of incentive,the marine movable platform will also perform irregular movements in space with multiple degrees of freedom.In this paper,a pendulum wave energy harvest device is designed.The fan-shaped pendulum is used as the energy capture agency of the device.Through the gear speed increasing transmission mechanism and the electromagnetic power generation module,the high power output of the energy harvesting device is realized.Aiming at the characteristics of device output voltage irregularity and low-frequency AC,this paper also designs two kinds of power management modules for voltage response,tracking and boost storage at different output frequencies.Through laboratory tests,large water tank tests,and marine experimental tests,the device is able to produce higher responsiveness to complex waves.The device can reach a maximum open circuit voltage of 10V in the laboratory test environment and the marine test environment.The maximum output power of the load is about 205mW.And the 200mAh lithium battery voltage can be charged from 3.12 V to 3.6 V in 4 hours.The main research contents of this paper include the following points:(1)Design and optimization of wave energy harvesterIn view of the random and multi-directional characteristics of ocean waves,this paper analyzes and determines the wave energy collection scheme of the pendulum capture energy mechanism.The device uses a gear speed increasing mechanism to convert the rotation and swing of the compound pendulum into high-speed rotation.The rotating mechanical energy is converted into electrical energy through an electromagnetic conversion module.A dynamic model of the plane pendulum under the excitation of ocean waves was established,and the influence of the performance parameters of the energy harvest device on the output performance was analyzed.Through ADAMS simulation software,the material,size and shape of the plane pendulum are optimized.The fan angle of the fan-shaped pendulum made of copper is 120°,the thickness is 3.5cm,and the radius is 4.5cm.Finally,the overall device is designed,processed and assembled according to the parameters.(2)Design and test of power management circuitAiming at the characteristics of irregular output voltage and low-frequency AC of the wave energy collection device,this paper designs two wave energy collection management circuits with different frequency power sampling and tracking.Both are rectified by the rectifier bridge and boosted by the BOOST circuit and then charged into the lithium battery.After that,they can be boosted to 12V for the secondary power supply.Compared with the power management circuit with low frequency power sampling and tracking,the high frequency circuit adds a clock module and a sampling comparison module.After experimental test and comparison,the low frequency sampling period is 16s,which can be used for longitudinal energy collection of ocean waves in high seas;the frequency of the high frequency sampling is 3 Hz,and the efficiency is 70%higher than that of the low frequency sampling.After the voltage is boosted,12V power is supplied to the outside,and the current can be maintained at 400mA,which can supply power to most miniature sensors in the platform.(3)Experimental test and data analysis of wave energy harvest deviceIn this paper,three parts of laboratory platform test,large water tank test and marine experimental test are carried out on the wave energy harvester.The laboratory platform test verified the the dynamic model of this paper.And the device has good adaptability to complex waves.In the large-scale water tank test,under a unidirectional wave with an average period of 2s and an average amplitude of 0.2m,the maximum power of the device is about 0.12W and the average power is about 23.5mW.In offshore experiments,the output effects of two pendulum energy harvesting devices,horizontal and vertical,were compared.The horizontal pendulum energy harvesting device is superior to the vertical pendulum energy harvesting device in both a more stable output voltage waveform and a peak voltage of up to 10V In the sea charging experiment,the device charged the 200mAh lithium battery voltage from 3.12 V to 3.6V in 4 hours,and the charging capacity reached 25%of the battery capacity.Experiments verify that the device can perform energy collection under ultra-low frequency and random waves.It has high output performance and application prospects,which is of great significance for the energy supply of marine movable platform and long-term unmanned observation in the open sea.