Research On Key Technologies Of Low-power And Low-frequency Electromagnetic Underwater Sound Source

In the field of marine acoustic information,the underwater sound source that is on duty on the seabed for a long time and works continuously and stably has important application value.This kind of sound source needs to have the characteristics of low frequency,low power consumption and high efficiency.The electromagnetic sound source has a natural advantage in low frequency because its resonant frequency is not limited by volume and mass.However,traditional electromagnetic sound sources are mostly high-power broadband sound sources,which have low electro-acoustic conversion efficiency and high power consumption,and are difficult to meet application requirements when space and energy are limited.In response to this problem,this paper has carried out several key technical researches on the improvement of electro-acoustic conversion efficiency of low-frequency electromagnetic sound sources,which is of great significance to the realization of low-power low-frequency electromagnetic sound sources.The main research contents of this paper are as follows:(1)A theoretical model of the acoustic efficiency and motor efficiency of the lowfrequency electromagnetic sound source is established.The electro-acoustic energy conversion process of the electromagnetic sound source is analyzed,and the electroacoustic efficiency and the motor efficiency of the electromagnetic sound source under the resonance state are mainly studied.Based on the electromechanical analogy method,a theoretical model of the acoustic efficiency of a low-frequency electromagnetic sound source machine is established,and a theoretical model of the sound source motor efficiency is established based on the principle of electric drive,which guides the problem of acoustic radiation loss in the back cavity of the sound source and the high-efficiency electromagnetic under low power.Research on drive technology.(2)Research on key technologies of cavity-backed acoustic radiation low loss.In the research on improving the acoustic efficiency of the electromagnetic sound source machine,the research on optimizing the diaphragm structure and improving the acoustic impedance matching of the diaphragm forward radiation has been relatively sufficient,but the problem of back cavity acoustic radiation loss has not been paid enough attention,hindering the sound source.Further improvement of the acoustic efficiency of the machine.In this regard,this paper firstly establishes an ideal back cavity radiation impedance model by means of theoretical derivation and simulation verification,and analyzes the backward acoustic radiation characteristics of the diaphragm under ideal conditions and the deficiencies of the ideal model of radiation impedance;then,the back cavity wall is considered.The influence of thermal viscous effect,the sound propagation loss characteristics in the back cavity were studied,and the theoretical model of the radiation impedance of the back cavity under the thermal viscous effect was established on the basis of it.The relationship between the acoustic efficiency and the stability of the resonant frequency of the sound source and the length of the back cavity is verified by simulation.(3)Research on key technologies of efficient electromagnetic driving force.By analyzing the problems existing in traditional electromagnetic transducers driven by low power,an efficient permanent magnet electromagnetic transducer is proposed.The finite element simulation verifies that the permanent magnet electromagnetic transducer has the advantages of higher driving force-to-current ratio and higher motor efficiency than the traditional electromagnetic transducer at low power.Then,it was applied to the drive of the low-power low-frequency electromagnetic sound source in this paper.With the goal of improving the efficiency of the motor,a series of optimization work was carried out on the permanent magnet electromagnetic transducer,which greatly improved the low-power low-frequency electromagnetic sound source.The motor conversion efficiency of the source.Finally,based on the above research content,the experimental prototype of electromagnetic sound source was developed,the experimental environment was built,the efficiency test plan of pool sound source was designed,and the verification experiments were carried out on two aspects of back cavity acoustic radiation low loss and high efficiency electromagnetic drive.The results show that the two key technologies studied in this paper can effectively improve the electro-acoustic conversion efficiency of low-frequency electromagnetic sound sources,which are correct and feasible.