| The comprehensive performance of direct current to direct current(DC/DC)converters is particularly important for the power supply reliability of switching power supplies.How to use more effective control strategies to improve the comprehensive performance of the converter has become a hot research topic in the field of power control technology.Although conventional PID control is a reliable digital control strategy,it often has the limitation of poor adaptability when used in nonlinear systems.The application of fuzzy controller to nonlinear systems can keep the system with good dynamic performance,but its control precision is not high enough to meet the comprehensive performance requirements of the converter.Aiming at the above problems,this paper adopts a control strategy that combines conventional PID control and fuzzy control,and optimizes PID control parameters in real time through fuzzy tuning rules to further improve the overall performance of the controller.The main research work of the paper is as follows:(1)This article first analyzes the working principle of the main topology Buck circuit.In order to determine the circuit component parameters and models,by analyzing the two working modes of the Buck circuit,the expressions of capacitance and inductance are deduced and the parameter values are obtained.The method of the state space average is adopted to establish the mathematical model of the topological loop and derive the transfer function of the output voltage to the duty cycle to prepare for the subsequent establishment of the system transfer function.(2)In order to analyze the system dynamic performance of conventional PID control and fuzzy PID control,the system transfer function is established by analyzing the working principle of each module of the system.Based on the theory of conventional PID control,the control parameter tuning method is analyzed and the frequency domain analysis method is used to complete the PID control Initial setting of parameters.Then the fuzzy control algorithm is further studied.The change law of the system response curve and the tuning method of PID control parameters are combined to optimize the design of the fuzzy rule table,then the final tuning of the fuzzy PID control parameters is completed.Finally,using Matlab/simulink tools to built for two control system models,and the simulation data is compared to obtain a better result of the dynamic performance of the fuzzy PID control system.(3)Aiming at the problem that the response speed of the traditional hardware circuit control system is not fast enough,the FPGA processor-based PID module and DPWM generator are designed,and the realization effect of the hardware circuit is verified through the modelsim software timing simulation.The response delay of the system is low and the PID is fuzzy Stronger comprehensive adjustment ability of control.(4)In order to verify the comprehensive performance of the controller in the actual circuit,an FPGA-based experimental platform is built according to the hardware circuit schematic diagram,and the comprehensive performance of the system is analyzed through the system startup response test,steady-state performance test and dynamic performance test.Comparing the experimental data,it is concluded that the system startup time of fuzzy PID control is shorter and the steady-state error is smaller,and the maximum steady-state error of the fuzzy PID control is about 0.38%;In the case of load current jumps,the overshoot of conventional PID and fuzzy PID is about 5.1% and 2%,and the self-adjustment time is 12.6ms and 7.6ms respectively.The comparison data shows that the fuzzy PID control makes the system overshoot smaller,the self-adjustment speed is faster,and the overall performance of the system is improved. |
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