Research On Nonlinear Control Methods Of DC-DC Converter

Switching power supplies are almost standard equipment for all power conversion equipments and are favored by experts in the electronics field.In recent years,under the trend of rapid expansion of the market scale of electronic products such as computers,military,communications and consumer products,the importance of efficient and stable power supplies for electronic devices has become more prominent.Moreover,with the sustained increasing use of electronic and electrical products,the requirements for the performance and quality of the power supply are desired to be higher and higher.One of the most effective ways to make a switching power supply system of good quality is to create a closed loop system with strong control capabilities.The general linear control method is greatly affected by the change of system parameters.Especially when the load variation is large,the switching converter will have defects such as poor dynamic performance and low steady-state accuracy.Nowadays,the requirements for high efficiency,high accuracy,rapidity and low cost of transmitting electric energy are getting higher and higher.The conventional linear control strategy can not fully meet the system performance index.In this context,high-precision intelligent nonlinear control strategies are gradually applied to the control of power electronic converters,especially in the control of DC-DC converters.In this paper,the research of Buck converter is carried out,and the realization methods of various nonlinear control systems are given.The nonlinear control methods applied are thoroughly analyzed and studied.The paper focuses on the following work:(1)The closed-loop control method of Buck converter is mainly discussed.The PID control strategy is analyzed by the linear control method.The control principle and parameter setting method are analyzed in detail.Finally,the PI double closed-loop controller is designed by analog control.The GPM method was used to adjust the relevant parameters and completed the modeling and simulation.(2)In order to improve the flexibility of control,the design method shifts from analog control to digital control,from linear control to nonlinear control,and the incremental PID controller is used to complete the construction of the digital DC-DC converter based on traditional DPID control.The simulation and verification are carried out.For the problem of nonlinear power supply and large overshoot of the above method,this paper presents the implementation method of fuzzy adaptive PID control system,which aims to improve the control ability of the control system.It is to use MATLAB to blur.The logic toolbox Fuzzy Logic Designer completes the design of the fuzzy adaptive PID controller and completes the modeling simulation.The test results verify that the three parameters of the PID controller can be adjusted in real time by the fuzzy system,which can make the switching power supply system have good dynamic performance and anti-interference ability.(3)The nonlinear sliding mode control technology is introduced into the switching converter,and the design of the conventional hysteresis sliding mode control system is completed.Then a fixed frequency indirect sliding mode control switching converter is presented,and MATLAB is implemented.Modeling and simulation test of the reaction speed when the system load changes;Finally,in order to provide effective control,the state power model is used to model the main power level topology,and the fuzzy sliding mode controller based on equivalent control is completed.The design and specific design description and numerical simulation are carried out.The simulation results verify the effectiveness of the scheme.Finally,the results of the above nonlinear control methods are compared and discussed.