| China is a maritime power with a long coastline and vast sea areas.To ensure the security of underwater national defense and the development of the marine economy,it is urgent to build a safe and reliable underwater long-distance detection and communication system.The power amplifier(PA),as the core equipment of underwater detection and communication systems,drives the electroacoustic transducer to emit low-frequency and high-fidelity sound waves at the source level.It has the application characteristics of high voltage,high power,harsh operating environment,and limited carrying space.Therefore,power amplifiers need to meet the requirements of low frequency,high voltage,high power,and high fidelity output capability,as well as high reliability and high power density characteristics.In low-frequency,high-voltage,and high-power applications,analog power amplifiers have high losses,large volume and weight,high distortion,and low power density of low-frequency link digital power amplifiers,and two-stage high-frequency link digital power amplifiers have limited efficiency and low reliability.The above topology makes it difficult to achieve both high voltage,high power,and high power density simultaneously.The single-stage high-frequency link digital power amplifier has advantages such as high-frequency transformer isolation,power device soft switching,and single-stage transformation.The cascaded multiple modules of high-frequency isolation can output high voltage and high power,and the device’s soft switching can reduce power loss.The single-stage transformation can improve system reliability and has advantages when applied to underwater detection and communication systems.Therefore,studying the key technologies of single-stage high-frequency link digital power amplifiers and constructing high fidelity,high reliability,and high power density digital power amplifiers with low frequency,high voltage,and high power output have important theoretical research value and engineering application significance for promoting the development of underwater long-distance detection and communication technology and equipment.This dissertation is presented in the National Major Scientific Research Instrument Development Project-Multi frequency and Multi directional Collaborative Sonar Measurement Instrument for Marine Underwater Moving Targets[52127901],the Key Project of the National Natural Science Foundation of China-Research on High Power Electroacoustic Efficient Energy Transfer Mechanism and Control Method [51837005],and the General Project of the National Natural Science Foundation of China-Research on Key Issues of Ultra Low Frequency Switching Power Amplifier with Integrated Supercapacitor Energy Storage [52177178]Supported by the Young Scientists Fund Project-Research on Key Issues of Extremely Low Frequency Switching Power Amplifiers for Marine Sonar Detection System [52207198] and supported by the National Research Center for Power Conversion and control engineering Technology,relevant research has been carried out around the modulation modeling,voltage spike suppression,double frequency power fluctuation suppression,coupling topology optimization and other aspects of single-stage high-frequency link digital power amplifiers.The main research contents and innovations include:(1)To solve the problems of difficult modulation design and low output fidelity caused by various switching modes of single-stage high-frequency link digital power amplifier,a universal modulation model of unipolar sine pulse width modulation(unipolar SPWM)was established,and a multi-pulse side unipolar SPWM(SSUSPWM)technology was proposed.A detailed analysis was conducted on the most basic implementation methods of modulation output for each level of primary unipolar SPWM(PSUSPWM)and SSUSPWM.A universal modulation model for PSUSPWM and SSUSPWM was established,revealing the unified modulation principle of unipolar SPWM and providing a unified design method.We have deeply explored the implementation methods of SSUSPWM and proposed the multi-pulse SSUSPWM technology.The simulation results show that the theoretical analysis of the universal SPWM modulation model of the polarity of the bill of lading is correct.The multi-pulse SSUSPWM technology multiplies the harmonic frequency of the SPWM voltage before filtering,reduces the output voltage THD from 2.53% to 0.61%,decreases by 75%,and improves the output fidelity of the power amplifier.(2)A multiplex active clamp voltage spike suppression method is proposed to address the issues of voltage spikes in single-stage high-frequency link digital power amplifiers,such as increased device voltage stress and reduced reliability.A detailed analysis was conducted on the mechanism of voltage spike generation in a single-stage high-frequency link digital power amplifier,a mathematical model was established,and corresponding voltage spike suppression strategies were provided.The reuse evolution of switching devices was derived,and a reuse-type active clamping method was proposed,which achieved leakage-induced voltage peak suppression with a low-cost and low-loss clamping structure.By combining multi-pulse SSUSPWM technology,a coupling frequency doubling modulation strategy is proposed to ensure high-fidelity output while reducing topology costs.The design of overlapping commutation avoids the generation of voltage spikes in the filtering inductance.The simulation and experimental results show that the proposed multiplex active clamping method eliminates the voltage spikes of the single-stage high-frequency link digital power amplifier,reduces the voltage stress of the switching device from 430 V to 240 V,reduces it by 44%,and improves the operational reliability of the power amplifier.(3)A multiplexed active power decoupling method for suppressing second harmonic power fluctuations in single-stage high-frequency link digital power amplifiers with single-phase low-frequency loads is proposed to address the issues of reduced reliability and power density caused by second harmonic power fluctuations.A detailed analysis was conducted on the mathematical mechanism of a power imbalance on the AC and DC sides,and the clamp capacitor was reused.A multiplex active power decoupling method was proposed,which simultaneously achieved voltage spike suppression and second harmonic power fluctuation suppression.A mathematical model for the power balance of the power amplifier’s second harmonic has been established,and an active power decoupling control strategy based on capacitor voltage error balancing control and deadbeat control has been proposed to achieve fast and effective power decoupling.The simulation and experimental results show that the proposed multiplex active power decoupling method eliminates voltage spikes while reducing the peak value of DC side current fluctuations from 18.37 A to3.37 A,reducing it by 82% and improving the power density of the power amplifier.(4)A dual half bridge optimized topology with fundamental frequency decoupling is proposed to address the complex structure and modulation difficulties caused by the input-output coupling of a single-stage high-frequency link digital power amplifier.The topology evolution of a single-stage high-frequency link digital power amplifier was derived,and a fundamental frequency full bridge decoupled input-output structure was designed.A dual half bridge single stage high-frequency link digital power amplifier was proposed,avoiding the use of bidirectional switches and simplifying the structure.A detailed analysis of the circuit mode and mathematical modeling were conducted,and a deadbeat control based on single phase shift modulation was proposed,which eliminates the need for control parameter adjustment and achieves rapid response and static error-free dynamic performance.The simulation and experimental results show that the proposed dual half bridge optimized topology can achieve high fidelity and high-efficiency output,without voltage spikes.It reduces the number of high-frequency switching devices from 12 to4,reducing by 66%,and improves the operational stability of the power amplifier.This dissertation takes the key scientific and technological challenges of high fidelity,high reliability,and high power density single-stage high-frequency link digital power amplifiers in the field of underwater remote detection and communication systems as the research background.It focuses on the difficulties in designing high fidelity modulation for single-stage high-frequency link digital power amplifiers under complex operating conditions in the ocean,reducing reliability due to high voltage peak stress,reducing power density due to second harmonic power fluctuations,and reducing stability due to coupling topology,We have conducted in-depth research on the relevant theories and methods of topology and control of single-stage high-frequency link digital power amplifiers from multiple aspects such as the general modeling of modulation and multi-frequency modulation,multiplexing active clamping method,multiplexing active power decoupling method,and fundamental frequency decoupling optimization topology.Strive to improve the fidelity,reliability,power density,and stability of single-stage high-frequency link digital power amplifier,and provide scientific theoretical guidance and technical reference for the engineering application of single-stage high-frequency link digital power amplifier.The research content covers the topology structure,modulation strategy,working mechanism,mathematical model,control method,parameter design,and engineering application design of a single-stage high-frequency link digital power amplifier,forming a relatively complete theoretical analysis method and power conversion control technology scheme for high fidelity,high reliability,and high power density single-stage high-frequency link digital power amplifier,It has important theoretical research value and engineering application significance for promoting the development of underwater long-distance detection and communication technology and equipment. |
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