Wave Energy Converter Technology Of Autonomous Underwater Vehicle Based On Hydraulic Power Take-off

Autonomous Underwater Vehicle(AUV),a convenient and efficient Marine mobile platform,is an essential tool for Marine resource exploration,underwater military reconnaissance,and remote equipment monitoring,and has great application value in military and civilian fields.However,power supply has always been a problem for AUVs.Batterypowered AUVs lack the ability for continuous power supply and need frequent launch and recovery during underwater operations,which limits the working ability and development of AUVs.In this paper,a wave energy aboard harvest device of AUV is designed.A pair of raft pendulums are designed for the AUV to capture wave energy,and a set of hydraulic power takeoff(PTO)devices is designed to convert the kinetic energy of the raft pendulums into hydraulic energy,and finally drive the generator to generate electricity so that the AUV can get power supplement in the Marine environment.The main contents of this paper are as follows:(1)Based on the three-level sea state,the overall structure design and hydraulic PTO system design of the raft pendulum-vehicle body wave energy power generation device(hereinafter referred to as the raft pendulum-body device)are carried out,and the working principle is expounded.The fluid dynamics modeling of the raft pendulum-body device provides a theoretical basis for the next computational fluid dynamics(CFD)simulation.(2)The ability of the raft pendulum to capture wave energy is analyzed and evaluated.STAR-CCM+was used to conduct CFD simulation on the raft pendulum system.The angular displacement,angular velocity,and wave torque of the raft pendulum relative to the vehicle body were calculated.The shape of the raft pendulum is optimized.A set of raft pendulum parameters is finally determined for the follow-up study by considering the energy capture ability and the influence on the vehicle itself.Five groups of wave height and five groups of wave period parameters were selected to study the influence of sea conditions on the energy captured by raft swing.(3)Modeling and optimization of the PTO system.The linear modeling of PTO and variable damping analysis were carried out to study the relationship between the generated power of linear PTO and system damping.The hydraulic PTO working circuit is designed,hydraulic PTO mathematical modeling and component selection are carried out,hydraulic PTO system simulation is carried out by AMESim,and hydraulic PTO variable damping is analyzed by changing hydraulic motor displacement and generator damping.(4)In order to make the PTO system applicable to actual sea conditions,based on the optimal damping analysis of the raft pendulum-body device,the maximum power point tracking algorithm based on the conductance increment method is designed.The hydraulic PTO is automatically optimized by co-simulation of AMESim and Simulink.The calculated results are compared with the hydraulic PTO’s variable damping analysis results.Verify the feasibility of the algorithm.