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

Power amplifiers are widely used in industrial testing,measurement,and submarine navigation,imaging,and ranging.Digital power amplifiers have gradually replaced analog power amplifiers in high power applications due to their advantages of high efficiency and high power density.The digital power amplifier studied in this paper is mainly to supply the core device of the laboratory underwater acoustic transduction platform-giant magnetostrictive transducer.At this stage,the laboratory transducer is developing towards high power.The digital power amplifier in this paper uses cascade The full bridge NPC(Neutral Point Clamped,NPC)structure realizes the capacity increase and pressure increase.In addition,the impedance characteristics of the transducer are affected by factors such as input current and water depth,which require high dynamic performance and robust performance of input current control.Therefore,this paper proposes a robust multi-layer model predictive control(RM-MPC).RMMPC overcomes the problems of the large amount of calculation and the high dependence of the model on the traditional model predictive control(MPC)applied to the cascade system.The main research contents are: topology structure and working principle analysis of digital power amplifier,research on robust multi-layer model predictive control,experimental device development and experimental verification.It will be discussed from the following aspects:(1)Research and analysis of the cascaded full-bridge NPC power amplifier topology.Each sub-module consists of a ZVS phase-shifted full-bridge converter at the front stage and a NPC inverter at the rear stage.The DC/DC converter can achieve electrical isolation and continuous voltage transformation,and the output waveform of the full-bridge NPC five-level inverter has high fidelity.The multi-module cascade topology can greatly improve the output voltage level and power level of the power amplifier.The topology and working principle of the digital power amplifier sub-module and the cascade system are analyzed;the linear model of the NPC inverter is established and the traditional PI controller is designed.(2)Aiming at the high fidelity requirements of the input current of giant magnetostrictive transducer load,a robust multilayer model predictive control(RM-MPC)is proposed.Establish a discrete model of cascaded full-bridge NPC inverter;in order to improve the robustness of the control system and reduce the dependence on the system model,a disturbance observer based on Kalman filtering is designed;traditional MPC will have a computational burden when applied to cascaded systems The big problem,this paper uses a hierarchical control structure to avoid repeated predictions and estimations,which greatly reduces the amount of calculation.The control objectives and working principles of upper-level control,middle-level control and lower-level control of robust multi-layer predictive control are introduced in detail;the computational advantages of RM-MPC compared with the limited control set MPC are quantitatively analyzed;theoretically verified Stability of multilayer MPC(3)Completed a 1k V/10 k W digital power amplifier prototype engineering design.The selection of hardware parameters of the main circuit of the amplifier is elaborated in detail;a control system with FPGA+DSP+CPLD as the core is constructed,and the design of related peripheral circuits is completed;a communication system composed of CAN,RS485,optical fiber and MCGS display is built.Finally,the construction of the five-module series test prototype is completed,and the verification of the robust multi-layer model predictive control is completed on the threemodule series platform,which proves that the multi-layer MPC is more stable and dynamic than traditional PI control.Advantages such as sex and robustness.