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Research On Digital Control Technology Of Phase-shifted Full-bridge DC-DC Converters

Posted on:2019-07-28Degree:MasterType:Thesis
Country:ChinaCandidate:W LiuFull Text:PDF
GTID:2382330548457043Subject:Electrical engineering
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With the development of high frequency,digital and miniaturization of switching power supplies,high-frequency switching power supply which based on digital control slowly becomes a hot research object in the power electronics field.Phase-shifted full-bridge soft-switching converter has the advantages of low output voltage ripple and high power supply efficiency,This paper will combine phase-shifted full-bridge ZVS converter technology with digital control technology to design digital phase-shifted full-bridge ZVS power supply system which based on DSP.The paper first describes the key technologies of the main power circuit hardware and calculates the main device parameters,then focus on voltage and current double loop feedback control strategy.The main work and conclusions are as follows.(1)Based on the working principle of the phase-shifted full-bridge ZVS power system to determine the overall design,and study the key technologies involved.First determine the overall structural framework of the system,then analyze the working principle of phase-shifted full-bridge ZVS converter and analyze its loss of duty cycle.The realization of the hardware circuit can not be separated from the application of several key technologies,including drive control technology based on IR2110,voltage and current sampling technology and spike current suppression technology.(2)According to the specific requirements of the system design,Calculate pivotal circuit component parameters of the main circuit.Based on data and previous design experience,perform detailed calculations and design of parameters such as high-frequency transformers,filter inductors,filter capacitors,and resonant capacitors which required for ZVS in the main power circuit;Discuss nd analysis of full-bridge inverter power MOSFETs,rectifier diodes and other devices,and finally determine the selected model.(3)Feedback control the main controller based on the selected DSP,study on Phase-shifted Full-bridge ZVS Power Supply System by digital control strategy.The DSP controller samples the output voltage and the transformer primary current,then use a certain control algorithm to control the occurrence of phase shift waveforms.This paper selects the voltage outer loop current inner loop double loop feedback digital control strategy,voltage loop compensation according to the frequency domain method,first establish a circuit model and then compensate for it by introducing a certain number of poles and zeros,current loop compensation which based on voltage loop compensation introduces peak current leading edge control algorithm.In addition,the generation method of the phase-shift driving waveform is also described.(4)Simulate the overall circuit and compare the results,test and verify system's feasibility,study and summarize the test results.After completing the design of the hardware circuit and its digital control algorithm,using Simulink to simulate and test the open-loop circuit,voltage single-loop feedback circuit and voltage-current double-loop feedback circuit respectively,comparing the simulation results and the conclusion is drawn that the voltage-current double-loop feedback strategy not only guarantees the steady-state accuracy of the system but also improves the response speed of the system.Finally test the actual production circuit,The output voltage is stable at 24 V,Power Efficiency 88%,Ripple level within ±1%,and when the input state is wide,the system output fluctuation is less than ±1%,fully confirming the design requirementsThe DSP-phase-shifted full-bridge ZVS power supply system designed in this paper has better steady-state accuracy and response speed than traditional phase-shifted full-bridge power supplies,include Low output voltage ripple,high operating frequency,high power efficiency,and it has good performance.
Keywords/Search Tags:Phase-shifted Full-bridge, Zero-Voltage-Switching, Frequency Domain Method, Digital Control Technology, Peak Current Control
PDF Full Text Request
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