Design And Research On Multi-Coil Structure Of Underwater Wireless Power Transmission System Against The Seawater Flow Vibration

The ocean is a treasure trove of rich resources.At present,when land resources are nearly exhausted,the development and utilization of marine resources is an inevitable trend of social development.The Autonomous Underwater Vehicle(AUV)Because of its high degree of intelligence,can be done in a complex marine environment complete underwater exploration,mapping,military reconnaissance and other tasks.Because AUV is limited by size,volume and weight,it has limited energy resources and cannot meet the needs of long-term work.Using underwater wireless power transfer technology(WPT)to recharge the AUV can not only increase the underwater operation time of the aircraft,improve the work efficiency,but also improve the concealment of the AUV,which has great practical value.This article takes underwater WPT technology as the background,and focuses on the eccentricity and offset between the primary and secondary coils.The main research objectives are to improve the tolerance to eccentricity and offset and transmission stability of wireless power transmission systems.The research contents mainly include:1.Analyze the energy transfer mechanism of the WPT system.First,the complex power model was used to analyze the energy transfer process in the primary and secondary side circuits,and the active and reactive power delivered by the coupled inductor were derived.Then the Poynting vector was used to analyze the distribution and flow of the electromagnetic field energy in the space around the two coupled coils,and Derive the active power passing through the intermediate infinite plane between the primary and secondary coils,and the transmission mechanism of energy from the power source to the load of the WPT system is revealed..2.Research the influence of coil eccentricity and offset on the transmission performance of the system in WPT system.For the WPT systems of the four basic compensation networks,the trend of the system parameters when the eccentricity and offset of the primary and secondary side coils are analyzed,as well as the voltage and current trends of each module in the circuit.By introducing a compensation network into the circuit,both the impedance transformation and the constant voltage or constant current output of the local circuit can be achieved,thereby improving the adjustment capability of the WPT system.3.Research the transmission characteristics of WPT system in seawater environment.Because the physical parameters of seawater and air are different,the WPT system circuit model applicable to air cannot be directly applied to the seawater environment.Through comparative analysis of the electric field distribution in seawater and air,it is concluded that eddy current loss and system detuning are the direct factors that cause the transmission efficiency of WPT system to decrease in seawater environment.Based on this,a modified mutual inductance model of WPT system in seawater environment is proposed.4.Research the multi-coil structure model with anti-offset and anti-eccentricity.Aiming at the eddy current loss caused by seawater and the coil offset and eccentricity caused by ocean current shock,three coil and four coil structure models were proposed respectively.The threecoil structure can not only reduce the eddy current loss,but also solve the impact of the primary and secondary coil offset problems on the transmission performance of the system.The fourcoil structure can form multiple coupled resonant circuits.Although the transmission characteristics in each coupled circuit change with the eccentricity of the coil,the overall transmission performance of the system is almost unchanged,which significantly improves the anti-offset and anti-eccentricity of the WPT system.