Design And Implementation Of Bidirectional Wireless Charging System For Autonomous Underwater Vehicle

The exploration and development of marine resources requires underwater detection equipment such as autonomous underwater vehicle(AUV)and underwater sensor(UWS).However,the power supply problem of underwater detection equipment restricts the work efficiency and applications.Wireless charging technology enables contactless charging to avoid short-circuit problems.At the same time,AUV,as a flexible detection device,can enter the charging dock to charge,but also to the UWS fixed-point operation of underwater equipment to provide electricity.Therefore,the bidirectional wireless charging system of AUV will be designed from the aspects of magnetic coupling device,bidirectional transmission resonant compensation network,bidirectional power control and experimental prototype.Aiming at the cylindrical AUV in this paper,by analyzing the magnetic flux coupling manner of ring-shaped and pot-shaped magnetic coupling devices,a magnetic flux closed in AUV circumferential is designed,and a magnetic coupling device based on dipole coil is designed.First,the flux coupling manner is analyzed from the traditional underwater magnetic coupling device,the structure design of the solenoid structure is carried out,and the influence of the magnetic coupling device is studied according to the requirements of the magnetic coupling device’s dislocation performance.The size of the misalignment performance of the magnetic coupling device is obtained by parameter scanning.In order to realize the magnetic coupling device,this paper studies the Fe-based nanocrystalline soft magnetic material,and the coupling ability is compared with the ferrite material through the magnetic field simulation software.Finally,combined with the internal space of the AUV,the magnetic field of the magnetic coupling device was simulated and tested.Simulation results show that the magnetic coupling device based on dipole coil has the characteristics of small size,well-coupling performance and strong magnetic field constraint.In order to realize underwater bidirectional wireless power transmission,the topology and parameters of the resonance compensation network are analyzed and designed.Through analyze the topology of the two-way wireless charging compensation network of electric vehicles,combined with the requirements of underwater two-way transmission power control,the forward LCL-S compensation network and the backward SS compensation network are adopted.By modeling the bidirectional wireless power transmissioncompensation network,the load voltage and output power of the system can be obtained.According to output voltage gain,output power,soft switching conditions,and so on,the bidirectional compensation network is designed.In PSpice,a simulation circuit is constructed to test the output power of the system and the working state of the switch in the case of misalignment,verifing the stability and effectiveness of the design of the two-way compensation network.By modeling the dynamical birdirectional wireless power transmission system,the stable operating frequency range of the system under dynamic conditions is obtained.By analyzing the load resistance of the lithium battery charging process and the bidirectional power control process,a bidirectional DC-DC power control circuit is designed.Buck power control circuit is used for forward transmission,and Boost power control circuit is used for backward transmission.The characteristics of bidirectional DC-DC power control impedance change are analyzed.The power control system is realized by establishing a bidirectional DC-DC closed-loop simulation model in simulink.Finally,the overall structure and control program flow of the bidirectional wireless charging closed-loop control are designed.In order to verify the feasibility of the bidirectional wireless charging system,a bidirectional wireless charging system test platform is established.First,the magnetic coupling device of Fe-based nanocrystalline soft magnetic materials is completed.Through the comparison with the simulation,the coupling ability can meet the design requirements.The main circuit of AUV side bidirectional transmission and power control,switch tube drive and voltage and current measurement circuit are designed.The openloop and closed-loop variable load and misalignment performances are tested on the bidirectional wireless charging system.The test results show that the open loop output power of the forward transmission is 650 W and the efficiency is 92.35% within the battery charging load range of the two-way wireless charging system.The open-loop output power of the backward transmission is 600 W and the efficiency is 89.67%.Simulation experiments verify that the forward wireless charging system achieves constant current and constant voltage charging through dual closed-loop control,and the backward transmission can meet the constant current charging requirements of the battery in UWS side.Finally,the forward wireless charging system tested that the current was stable at 10.8A during the constant current charging process,and the load voltage was always 54.7V at the constant voltage charging prcocess.The overall efficiency was above84%.In the case of rotational misalignment and axial misalignment,the closed-loop control system of backward wireless charging system can maintain the charging current of the battery at 10 A.The output power reaches 400 W,and the overall efficiency exceeds 80%.