Research On Three-dimention Omnidirectional Underwater Wireless Power Transfer Method

For a long time,providing stable,safe and efficient power supply for underwater mechanical and electrical equipment has always been an important issue in deep sea engineering.Compared to the complex docking mechanisms,the existence of hidden danger and the expensive price of the traditional wired charging method,wireless power transfer technology can transmit power without any electrical contact between the power supply and the electrical equipment,which can provide an effective solution for the disadvantages of wired charging.The magnetic resonance coupling wireless power transfer(MRC-WPT)technology has moderate transmission distance,high transmission efficiency,and is not sensitive to the surrounding environment.Therefore it's most suitable for the subsea operation.Compared with the terrestrial MRC-WPT technology,the eddy current loss of seawater medium reduces the power transfer level,and the wave quality in the seawater environment makes the transmitting and receiving coils unable to be strictly aligned.Therefore,based on the equivalent circuit and the magnetic field distribution,the power transfer characteristics of underwater MRC-WPT are studied,and the corresponding solutions are put forward for the existing problems and shortcomings.Aiming at the influence of eddy current loss on power transfer level,a wireless power transfer method based on parameter switching is proposed.The eddy current loss of the seawater medium limits the operating frequency of the system.In the low frequency condition,the transfer characteristics of the parallel resonant coupling are better than the series resonance for the 50 ohm nominal port impedance.Based on the basic theory in the equivalent circuit and the network port,the equivalent circuit model of eddy current loss is analyzed,the wireless power transfer characteristics of parallel resonant coupling wireless power transfer are derived by completely independent,a method of parameter switching is put forward,the circuit parameters or coil parameter switching in different range of distance to optimize the overall level of power transfer.Aiming at the contradiction between the strict alignment requirements of the traditional MRC-WPT technology and the fluctuation of the working environment of the seawater,a three-dimension omnidirectional wireless power transfer method is proposed,to provide a stable and efficient power supply for electric equipment in the seawater environment.Therefore,this paper starts from the near field distribution of the magnetic field of the transmitting coil,then proposes a new structure of the transmitting coil,and studies the optimal feeding phase difference,so as to maximize the transmission efficiency,and investigates the feasibility of multiple simultaneous charging of the receiving coil.In the end,the simulation results show that the system proposed processes the capability of omnidirectional power transfer in three-dimension space.