Research On Digital Control Methods Of Buck Switching Power Supply Based On FPGA

DC-DC converters are widely used in computers,home electronics,aviation and other fields because of its simple structure.With the rapidly development of electronic products,design requirements are higher for the power chips.Due to many significant advantages such as high frequency,miniaturization and intelligence of digital controlled switching power supplies,it has gradually become the mainstream of design fields for power supplies.Among varies of implementations for the digital controlled switching power supplies,FPGA has become a popular research subject due to their unique characteristics of field programmable.In this paper,a Buck-type DC-DC converter is used as the main circuit topology,and corresponding digital controlled system is constructed based on FPGA.The main work of this thesis includes:(1)The working principles and modes of the Buck converter are introduced,and the small signal model of the converter is established.Firstly,circuit parameters of the power stage are designed.Then,the common modulation methods,analog/digital control methods of DC-DC converters are analyze.Furthermore,the DPWM pulse width modulator and discrete position DPID are constructed after fixing the controller parameters based on ZN tuning method.(2)The power stage Buck circuit and its control stage models,such as PID and PWM,as well as A/D conversion model are modeled,using MATLAB/Simulink.The correctness of the above modules are verified one by one with simulation methods.Then the whole system are modeled under MATLAB/ Simulink,and the simulation results are analyzed.This method provides a basis for the design and parameter selection of FPGA-based digital control systems.(3)The key modules of the digital control system are programed using Verilog language under the Quartus?platform,and the programing codes of each module are tested.After the key module codes are successfully tested,the RTL model is formed though modularization and instantiation.The experimental results are obtained withModelSim and MATLAB/Simulink.The results show that the output voltage of the Buck digital switching power supply system is stable at 1.8V,which meets the experimental design requirements.In conclusion,FPGA and ADC chip,as well as other circuit components required for the design are selected,which will be used to complete the hardware design of the Buck digital control system.