Research On Underwater Inductively Coupled Power Transfer System Using Saturable Reactor

The marine resources are abundant and diverse,and many countries around the world are paying more and more attention to the exploitation and utilization of it.Submarine observation networks and underwater navigation equipment are widely used.Batteries or plug connectors is used in underwater power supply.It requires large-capacity energy storage batteries or long cables,which severely limits the application of underwater equipment.This paper proposes to use the inductively coupled power transfer(ICPT)method to supply power to underwater equipment.A saturable reactor(SR)is used as the adjustable element for the underwater ICPT.The system is dynamically tuned and regulated,and the harmonic characteristics of the ICPT system using a saturable reactor are studied in depth.In this dissertation,the development status of underwater ICPT system is studied.It is proposed that LC compensation is used on the transmitting side and series compensation is adopted in the receiving side.The topology is modeled by generalized state-space averaging(GSSA)and mutual inductance circuit model.Considering the frequency bifurcation phenomenon of LC/S compensated ICPT system,the main factors affecting the output voltage are clarified through comparative analysis.Compared with air,seawater is electrically conductive.When electromagnetic waves propagate in seawater medium,there exists eddy current effect.The eddy current loss is simulated by COMSOL multiphysics simulation software.The experimental platform is used to analyze the eddy current loss in seawater environment,and influence of coupling distance and the frequency on eddy current loss.The ferrite core is used to measure the magnetization curve under different DC excitations by using ferrite software.The magnetoresistance model is established for the saturable reactor,and the relationship between the AC equivalent inductance value and the DC current is obtained.A controllable saturable reactor was designed and fabricated,and the simulation was verified by COMSOL.In order to ensure the constant voltage output of the underwater ICPT system,considering the influence of load and coupling coefficient changes on the output,the saturated reactor is used as the adjustable inductor,and the PID closed-loop control is used to dynamically adjust the AC inductance to realize the regulated output of the ICPT system.The DC side control adopts Buck circuit,PWM control changes the output current of Buck circuit,and the voltage signal is transmitted by NRF24L01 module.The saurable reactor generates a high-frequency odd-order harmonic when it is in saturation state.This part of the harmonic energy can be transmitted to the load side to improve the transmission power of the ICPT system.Finally,the high-frequency inverter power supply and coupling mechanism are designed and constructed,and the underwater ICPT system experimental platform is built.The underwater constant voltage output is realized when the switching load and the coupling coefficient change.