Fractional PID Predictive Function Control Application Research In DC/DC Converter

The DC/DC switching converter is a time-varying nonlinear switching circuit.Its modeling method,controller design and dynamic performance research have always been hot issues in the field of power electronics.At present,for the modeling problem of DC/DC converters,most of the researches use approximate equivalent and linearization methods to obtain linear time-invariant models,and then analyze the DC/DC converters based on traditional linear control theory.The controller is designed,but the dynamic performance of the DC/DC converter designed by this method is often difficult to meet the requirements,especially when it is interfered by external factors.In view of this situation,this paper establishes a more accurate piecewise affine model(PWA)based on the switching characteristics of the DC/DC converter,and combines this model with the fractional PID predictive function control algorithm(FOPIDPFC),and then combines it Applied to single-channel Buck DC/DC converters and parallel Buck DC/DC converters,experimental data shows that the FOPIDPFC control algorithm based on the PWA model significantly reduces the load caused by sudden changes in the DC/DC converter Adversely,it effectively improves the dynamic performance of the DC/DC converter.The main content of this article is divided into the following points:(1)First,in view of the inaccuracy of traditional DC/DC converter modeling,a PWA model in the switching system is proposed,and a segmented affine model of Buck DC/DC converter is established based on the knowledge of switching system modeling.Then the theoretical knowledge of the FOPIDPFC control algorithm is introduced in detail,and the optimal control amount of the FOPIDPFC control algorithm based on the PWA model of the Buck converter is derived.At the same time,because there are many parameters that need to be adjusted in the FOPIDPFC control algorithm,a particle swarm intelligence algorithm(PSO)is proposed to solve some parameter problems of the FOPIDPFC controller.(2)The implementation process of the PSO algorithm and its related parameter selection principles are described in detail,and then the simulation model of FOPIDPFC control single-channel Buck converter is built in MATLAB/Simulink,and the simulation link of particle swarm optimization optimization parameters is added.The simulation results are used to analyze the influence of the FOPIDPFC control algorithm on the dynamic performance of the system.(3)According to the idea of the master-slave current sharing method,a parallel Buck converter controlled by the master-slave FOPIDPFC is designed,and then a simulation model of the master-slave FOPIDPFC controlled parallel Buck converter is built in MATLAB/Simulink.Control effect from FOPIDPFC control algorithm.(4)A hardware experiment platform based on FPGA(including single-channel and parallel Buck converters)was built.In the Quartus II software,we used Verilog HDL to write the experimental programs of the three control algorithms of dual closed-loop PI,FOPIDPFC and master-slave FOPIDPFC,and then completed the experimental verification of several control algorithms on the experimental platform.By comparing Buck converters in different the experimental results under the control algorithm further show the superiority of the FOPIDPFC control algorithm designed in this paper.