Time Domain And Frequency Domain Analysis Of Buck Converter Sliding Mode Control System

As a basic but very important device,DC-DC converters have been widely used in many fields such as computers and aerospace.Compared with traditional PI control,sliding mode control can maintain good dynamic and static characteristics when the load changes in a wide range,and is insensitive to parameter changes.However,the current research results mainly focus on the design of the controller,and the performance indicators are mostly limited to the stability in the time domain.How to quantify the control performance in the frequency domain is rarely studied,which is the focus of current research in the SM control field.This article takes Buck converter as the research object,aiming at both time domain and frequency domain,from the perspectives of modeling and controller design,from circuit parameter perturbation to external disturbance,and covers stability,response time,and regulation.Various performance indicators such as time and overshoot are carried out to study the mechanism of factors that restrict the performance of DC converters under SMC control,which can improve the voltage quality of DC converters.The response time estimation of Buck converter under the action of SMC is studied in the time domain.Taking the non-singular terminal sliding mode method as an example,the system is ingeniously studied from the perspective of the phase trajectory analysis of the system in the phase plane,and the system motion law under the action of different given voltages is studied,and the system is proved theoretically The unidirectionality of the movement direction,and the accurate response time of the system is calculated in sections,which overcomes the difficulty of obtaining the response time due to the inability to calculate the approaching movement time in the traditional method.Using the description function method and the Nyquist stability criterion in the frequency domain,a new method of designing the Buck converter SMC controller is studied.Based on SMC’s direct on-off control and duty cycle control,the two realization methods,the DF method is used to realize the linear approximation of the nonlinear link of the controller,and the corresponding transfer function closed-loop control system block diagram is deduced.Specifically,for direct on-off control,from the perspective of practical system applications,this paper focuses on the impact of hysteresis modulation nonlinearity used in SMC’s theoretically infinite switching frequency on system control performance;for duty cycle control,Two commonly used Twisting and Super-Twisting continuous SMC algorithms are taken as examples to alleviate the impact of conventional direct on-off control switching nonlinearities on the system,and focus on the quantitative impact of external voltage disturbances on the system.Considering Buck converter modeling and SMC controller design,taking into account both time domain and frequency domain analysis,stability,regulation time and overshoot,improving the dynamic and static performance of Buck converters.In particular,the parasitic parameters of the converter are considered in the modeling process,and the influence of different parasitic parameters on the low-frequency and high-frequency characteristics of the system is derived;then the coordinated controller is designed by combining the SMC and Backstepping methods to realize the multiple performance indicators of the system in stages.