Key Technologies And Equipment Development Of High-power And Low-frequency Electroacoustic Transducer System

The ocean is located at the defense outpost,and thus is an important barrier to maintaining national security.The ocean is also the important carrier of China’s policy "the land and maritime Silk Road initiative" strategy.Underwater communication and underwater monitoring are the important technologies in oceanography;and they are the core support for all-around marine monitoring,underwater long-distance information transmission,and submarine resource exploration.The research of underwater communication is important for safeguarding China’s maritime rights and enhancing China’s marine military strength.Studying the key technologies of highpower low-frequency electroacoustic transducer system will realize the "underwater radar".Thus,the high-power low-frequency electroacoustic transducer system can provide an important guarantee for national economic development and nat ional governance capabilities.This thesis is funded by the National Natural Science Foundation Key Project of China "Research on Mechanism and Control Method of High-Power and HighEfficiency Electro-acoustic Transduction" [51837005] and the Hunan Science and Technology Innovation Plan Project "Development of Key Technologies and Major Equipment for High-Power Ocean Communication Electro-acoustic Transducer System" [2017XK2104].The research focuses on the high-power low-frequency electro-acoustic transducer system modeling,system analysis,and experimental equipment.The main works are reflected in the following five aspects:(1)The multi-field coupling model and impedance model of the multi-vibrator giant magnetostrictive transducer are established,which considers the multiphysics coupling characteristics of the giant magnetostrictive transducer.Based on the electro-magnetic conversion model and magneto-mechanical conversion model,the electro-magneto-mechanical coupling model and impedance model of the multi-vibrator giant magnetostrictive transducer are established.The model includes the internal magnetic field characteristics and mechanical characteristics of the transducer,and thus,can accurately reflect the displacement output characteristics and impedance characteristics of the transducer.Based on the model,the influence of the structural parameters on the characteristics of the giant magnetostrictive transducer is analyzed.Simulation and experimental results verify the accuracy of the models.(2)A steady-state mathematical model of the full-bridge modular multilevel power amplifier is established,which considers the internal dynamics of modular multilevel power amplifier.Based on the model,the control method of the power amplifier for high-power low-frequency electro-acoustic transducer system is proposed.According to the relationship between the arm currents,capacitor voltages,the arm voltages and the input currents,the output currents,the steady-state model of the full-bridge modular multilevel power amplifier is developed.Based on the model,the control method of the power amplifier for a high-power low-frequency electro-acoustic transducer system is proposed.The control method makes the input currents of the power amplifier balanced under unbalanced voltage.Furthermore,the amplifier can output a linear variable frequency current by the proposed control method,which meets the requirements of the transducer.Simulation and experimental results verify the accuracy of the full-bridge modular multilevel power amplifier model and the feasibility of the control method.(3)According to the nonlinearity and periodic time-varying characteristics,the input and output impedance models of the full-bridge modular multilevel power amplifier are developed.The input and output impedance models of the full-bridge modular multilevel power amplifier are developed by the harmonic state-space(HSS)modeling method.The proposed impedance models include the internal dynamic of the full-bridge modular multilevel power amplifier,and thus,ensures the accuracy of the impedance model.Simulation and experimental results verify the accuracy of the proposed impedance model.(4)According to the demand for stability and dynamic performance,the influence of control methods and parameters on the stability and dynamic performance of the high-power low-frequency electro-acoustic transducer system is studied.Combining the models of the giant magnetostrictive transducer and the full-bridge modular multilevel power amplifier,a comprehensive model of the high-power lowfrequency electroacoustic transducer system is established.Based on the comprehensive model,the stability and dynamic performance of the electroacoustic transducer system are analyzed.The effect of the control parameters and methods on the stability and dynamic performance of the system is analyzed.The simulation results verify the effectiveness of the analysis.(5)An experimental prototype of a high-power low-frequency electroacoustic system is developed.The electromagnetic conversion module and magneto-mechanical conversion module of the giant magnetostrictive transducer are established.The experimental prototype of the giant magnetostrictive transducer is established by assembling the modules.Subsequently,the circuit and control circuits of the full-bridge modular multilevel power amplifier are designed.The experimental prototype of the power amplifier is established.Finally,the high-power low-frequency electro-acoustic system is established by combining the giant magnetostrictive transducer and the power amplifier.The system is tested through experiments.The experimental results show that the high-power low-frequency electroacoustic system has the characteristics of high sound source level,which can realize the long-distance detection of underwater targets.