Research On Control Method And Equipment Development Of Modular High Voltage Digital Power Amplifier

The rapid development of the marine communication technology puts forward higher technical requirements for the operation performance and control methods of the high power electro-acoustic transduction system.As the key equipment in the electro-acoustic transduction system,high power digital power amplifiers(DPAs)have urgent problems in fidelity,stability,reliability,and operation efficiency.The modular high voltage digital power amplifier(MHVDPA)can be applied to high power electroacoustic transducer applications supplied by the submarine high dc voltage,with the advantages of high redundancy and low harmonic output characteristics without step-down transformer.It is a promising high-voltage and high-power digital power amplifier.The research for the modulation strategy and optimized control methods of the MHVDPA benefits for improving the output performance,system stability and operation efficiency of the power amplifier.Therefore,it is significantly meaningful for realizing high fidelity,high stability,high reliability and high operation efficiency of the high-voltage and high-power DPA in research significance and engineering value.This thesis is supported by the National Natural Science Foundation Key Project of China 'Research on High-power and High-efficiency Electro-acoustic Transduction Mechanism and Control Method'[51837005],and National Electric Power Conversion and Control Engineering Technology Research Center.The research content focuses on the output performance,system stability,capacitor voltage predictor,power loss and equipment development design of the MHVDPA.The main work and innovations are reflected in the following five aspects as:(1)The 2N+1 single carrier modulation strategy and the submodule(SM)capacitor voltage ripple suppression strategy are proposed to realize the high output fidelity of MHVDPA.Compared with CPS-PWM strategy,the traditional NLM strategy has the advantage of low design complexity of controller without individual capacitor voltage balance control and multi-carrier generators.But the harmonics of the traditional NLM strategy are relatively higher than those of CPS-PWM strategy.Therefore,a 2N+1 single carrier modulation strategy is proposed to realize the decrease of the output harmonics under the guarantee of complexity of the controller reduction.Furthermore,the capacitor voltage ripple suppression strategy is proposed to reduce the influence of voltage ripple on the output harmonic characteristics.The simulations and experiments validate that the proposed modulation strategy and voltage ripple suppression strategy could guarantee high output fidelity of MHVDPA.(2)Aiming at the problems of low-frequency oscillation,2nd frequency resonance,and energy imbalance,a circulating current control method applying for MHVDPA is proposed to realize the internal energy balance and system stability of MHVDPA.The phenomenon including the internal low-frequency oscillation,2 nd frequency resonance,and energy imbalance of arms of MHVDPA are studied,and the influence of the phenomenon on the system stability is analyzed.The energy balance circulating current control method is proposed and the circulating current controller parameters are optimized to improve the suppression effect of harmonic circulating current resonance and energy imbalance and the system stability.The simulations and experiments validate the feasibility and effectiveness of the proposed circulating current control methods.(3)The predictor-corrector algorithm with single voltage sensor measurement for capacitor voltages is proposed to realize the reliable operation of MHVDPA.Aiming at the problem that the individual measurement affects the reliable operation of MHVDPA under the individual voltage sensor fault condition,the predictor-corrector algorithm with single voltage sensor measurement for capacitor voltages is proposed based on the individual measurement.One voltage sensor is configured at each arm to measure the arm voltage,and the predictor accuracy of the capacitor voltage is improved by the predictor-corrector algorithm to achieve the capacitor voltage balance control.The simulations and experiments validate the feasibility and effectiveness of the proposed predictor-corrector algorithm with single voltage sensor measurement.(4)The loss optimization circulating current injection method is proposed to realize the high operation efficiency of MHVDPA.The loss calculation model of MHVDPA with 2N+1 single carrier modulation strategy is established.It is analyzed that the power loss is proportional to the absolute average value of arm current.Based on the analysis,the loss optimization circulating current injection method is proposed.The amplitude and phase angle of the injected circulating current reference is optimized and the power loss and operation efficiency of MHVDPA with different circulating current references are compared.The simulations and experiments validate the feasibility of the proposed loss optimization method.(5)The 3kV/50kW MHVDPA experimental equipment is developed,and the main circuit hardware parameters,control system structure and software implementation of the equipment are elaborated.The main circuit,the control circuit and the control system software of 3kV/50kW MHVDPA experimental equipment are designed.And the MHVDPA experimental equipment is tested under the condition of startup charging of power module do side,steady-state operation,and transient operation.