| In recent years,with the rapid development of marine development and national defense construction,underwater remote communication and detection technology play an increasingly important role.Sound wave is the only means of underwater longdistance communication,which is mainly emitted by electroacoustic energy conversion system.Power amplifier is the core equipment of electroacoustic energy conversion system.With the increasing requirements o f marine communication and detection technology for the power,frequency band,fidelity and reliability of electroacoustic energy conversion system,high-power,broadband,high fidelity and high reliability power amplifiers are needed to continuously enhan ce the output performance of electroacoustic energy conversion system.Therefore,the research of high power,broadband,high fidelity,high reliability power amplifier has great theoretical research significance and engineering application value.Based on the National Natural Science Foundation Project "high power electro acoustic energy conversion mechanism and control method research"(51837005)" ?the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(2017ZT07G237)and the national key research and development program " basic theory research of flexible DC fault current suppression "(2018 YFB0904600)",this paper carries out theoretical research,simulation analysis and experimental verification on high power,broadband,high fidelity and high reliability power amplifier.The specific work is as follows:(1)The topology,broadband control and DC bias suppression methods of digita l power amplifier are summarized.Firstly,the technical characteristics and applications of analog,digital and hybrid power amplifiers are analyzed.Secondly,the topology of digital power amplifier is introduced,and then the existing broadband output c ontrol and DC bias suppression strategies of digital power amplifier are studied.Finally,combined with the performance index of the project requirements,the appropriate digital power amplifier topology and control scheme are selected.(2)In order to meet the requirements of wideband and high fidelity of digital power amplifier,the parameter design scheme of LCLC output filter and the optimization design method of wideband output control are proposed.Firstly,the mathematical model of digital power amplifier is established,and the block diagram of open-loop control system is deduced.Secondly,for the LCLC output filter,the switching frequency of the switch is selected.On this basis,the LCLC filter parameter design scheme is proposed based on the inductance current ripple,capacitor voltage ripple and capacitor absorbed reactive power,and the filter parameter values are obtained.Then,in order to improve the steady-state and dynamic performance of the control system,a broadband output control optimization design strategy based on the evaluation criteria of system stability,dynamic response,output bandwidth and output impedance is proposed,and the controller parameters of the four control schemes are optimized High fidelity control strategy: output voltage outer loop,capacitor current inner loop control.Finally,the simulation model is established to compare and analyze the steady-state and dynamic performance of the four control schemes,which verifies the correctness of the theoretical analysis.(3)Aiming at the high reliability requirement of digital power amplifier,an improved virtual capacitance method based on voltage compensation is proposed to suppress DC bias.Firstly,the reason of DC component in the output voltage of digital power amplifier is analyzed in detail.Then the basic principle of virtual capacitance method is introduced,and the reason of steady-state error of output voltage amplitude in this method is explored.On this basis,and according to the optimal control strategy of broadband output in the second chapter,an improved virtual capacitance method based on voltage compensation is proposed,which eliminates the DC component in the output voltage and realizes the zero error tracking.At the same time,this method does not affect the optimal control strategy in the second chapter,and the output bandwidth and thd are basically the same.Finally,a simulation model is built to verify the theoretical analysis results.(4)A 10 k W wide band digital power amplifier prototype is developed.In terms of hardware,the design of DC side capacitor,switch device and filter selection of power amplifier are introduced,and the design of controller circuit,sampling circuit,fault protection circuit and drive circuit are described.In the aspect of software,the display interface of upper computer is designed,and the sampling subroutine and fault protection subroutine are written.Finally,the digital power amplifier is tested under the conditions of no-load,resistive load,transformer and transducer load,and the efficiency is more than 97% and thd is less than 1% at rated power. |
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