Research On Energy Conversion Efficiency Of Counter-rotating Self-adaptable Wave Energy Converter Based On Heaving Motion

With the increasing application of small marine equipment in various fields,the continuous energy supply of equipment has become an urgent problem,which restricting the performance and endurance of small marine equipment.The development and utilization of marine environmental energy makes it possible to solve this problem.As an important part of the marine environmental energy,wave energy has the characteristics of high energy density,cleanness,renewability,large reserves,which is also an important method to solve this problem.Aiming at the energy supply problem of small marine equipment,this paper proposes an adaptive type micro wave energy conversion device.The device uses the heave motion as the basic motion form for capturing wave energy.Focusing on the energy conversion mechanism and conversion efficiency of the wave energy converter,the following main work is carried out in this paper.1.This paper proposes a novel wave energy conversion mechanism based on heave motion and designs a novel counter-rotating self-adaptable wave energy converter.This paper analyzes the wave characteristics of regular waves and irregular waves from the basic components of waves,namely simple two-dimensional harmonics and basic hypothetical equations of hydraulic physics.Based on this,the energy havesting principle of the heave wave energy converter is analyzed by the spring damping model,and the power spectrum of the energy converter is obtained.The influences of natural frequency and working bandwidth of the converter on the conversion efficiency are analyzed.Based on the wave theory and the energy harvesting principle of wave energy converter,a counter-rotating self-adaptable wave energy converter is proposed.The design principle and working mechanism of the conversion device are introduced in detail.2.In this paper,the mathematical model of the counter-rotating self-adaptable wave energy converter is established,and the energy conversion efficiency and generated power of the converter are studied.Several key factors affecting the power generation efficiency of the wave energy converter are analyzed and discussed.The linear wave theory and the Froude-Krylov hypothesis method are used to calculate the vertical wave forces of different shapes of floating bodies,and the optimal floating body scheme is obtained.Based on the linear momentum theory,the mathematical model of underwater power take-off is established.The generated power of the wave energy converter is predicted and some numerical simulations are carried out.The experiment of hydrostatic environment was carried out on the energy conversion efficiency and generated power of the converter,and the causes of energy loss were analyzed.3.This paper proposes a power matching strategy for the electrical energy conversion system of the wave energy converter.The DC generator was modeled and a DC generator performance test system was set up.The influencing factors affecting the power generation efficiency of generator were analyzed experimentally.The filter circuit based on supercapacitor is modeled.Simulations in Simulink are used to analyze the filtering performance.The recharging power matching strategy of lithium battery was established.The recharging circuit of lithium battery,voltage regulator and lithium battery were modeled and simulated in Simulink.In order to verify the overall power conversion performance of the electrical conversion system,the whole system was simulated in the Multisim,and the performance of the filter circuit,voltage regulator circuit and recharging circuit were discussed.4.In this paper,an experiment platform in a wave-tank was established,and the experiments of conversion efficiency and generated power of the wave energy converter were carried out.In the wave-tank,the experimental research on the energy conversion efficiency and generated power generation of wave energy converter under different wave heights,periods and counterweights were carried out.Based on this,the experimental research on the energy conversion efficiency and generated power of the wave energy converter are studied under irregular wave conditions.