The Research On The High Power Modular Waveform Generator

With the urgent needs of motor frequency control and impedance measurement of new energy generation equipment,waveform generators as the core components have been highly valued and studied by scholars at home and abroad.The high-power DWG is a specific waveform generation device whose frequency and amplitude are continuously adjustable,and its development has a significant role in promoting the energy and power industry.This article takes the high-power,low-harmonic,wide-band,high-precision high-power digital waveform generator device as the research object,and studies its topological structure,single module control and multiple parallel key technologies to improve system reliability,efficiency and high output quality.It will provide important theoretical and practical guidance and is of great significance in promoting the development of smart grid,electric traction,metallurgy and mining.The main work and innovation of this paper are mainly reflected in the following aspects:(1)The background and significance of the topic of high-power digital waveform generator are described.The research status of the topology structure and control strategy of high-power digital waveform generator is introduced.The research content of this paper is briefly described.(2)The control strategy of digital waveform generator is analyzed.For the part of the pre-stage PWM rectifier,the control delay of traditional deadbeat control is inconsistent with the model inductance mismatch,and a method against compound prediction deadbeat control is proposed,which enhances the robustness of the model inductance change.For the secondary PWM inverter part,double closed-loop control of external loop quasi-proportional resonant current and inner loop PI is adopted to realize the performance of continuously adjustable output frequency and amplitude with low distortion rate.The model of the digital waveform generator control system is established and the transfer function of the control system is calculated.Then system control parameters is designed,while a simulation platform is built by using the PSIM simulation software to verify the effectiveness of the proposed control strategy.(3)The mechanism of the circulating current of multiple digital waveform generator parallel system is studied.The influence of the difference of the output voltage of the waveform generator and the equivalent output impedance on the circulating current is simulated and analyzed.In order to accurately distribute the power between the waveform generator parallel systems,an improved droop control ?virtual resistance control strategy is presented in this paper.Two digital waveform generator parallel system simulation platforms are built by using PSIM simulation software to verify the effectiveness of the circulation suppresses strategy.(4)A single 20kW waveform generator device prototype is developed and two parallel devices are built.The hardware and software design and implementation process of the device are explained.The hardware circuit design of the device mainly includes power switches and driving modules,heat dissipation modules,main circuit parameter design,signal acquisition module,fault detection and protection module,and human-machine interaction system.The software main program,each interrupt service program and liquid crystal communication program flow chart are introduced.Then elaborated the structure of each module unit,parameter design and component selection.Finally,the experiments are carried out to verify the effectiveness of the control method.