Chaos Studies Of Buck Converters And Their Control Strategies

As the core part of switching power supply,Buck converter is widely used in the field of power electronics,the nonlinear behavior caused by high frequency switching of switching devices in the circuit structure increases the complexity of the system.At some circuit parameters,the voltage-controlled Buck converter will appear chaotic.When chaos occurs in the converter,the stability of the converter is poor,and its performance will be greatly reduced.Therefore,it is of great significance to analyze the chaos phenomenon of Buck converter and realize chaos suppression.In this paper,the voltage-controlled Buck converter under Continuous Conduction Mode(CCM)is studied.Firstly,nonlinear dynamics is used to analyze the chaotic phenomena of the converter.Then,chaos suppression is realized to make the converter work in stable period 1 state.Finally,the parallel current sharing control of Buck converter is realized based on chaotic synchronization characteristics,and the parallel current sharing effect of Buck converter is improved.The main work of this paper is as follows:(1)The piecewise smooth switching model and precise discrete iteration model of voltage controlled Buck converter are established to analyze the operating characteristics of the converter system.The chaotic characteristics of the system are described by bifurcation diagram,phase diagram,time domain diagram and periodic orbit diagram.(2)A nonlinear controller and a terminal synovial-film active disturbance rejection controller are used respectively to suppress the chaotic phenomenon of the voltagecontrolled Buck converter.Based on the terminal sliding mode active disturbance rejection controller,a double closed-loop control strategy is designed,which further optimizes the performance of the converter and can suppress the chaotic phenomenon from the source.(3)The chaotic synchronization control of Buck converter system is realized by using the terminal sliding mode control rate designed in this paper.Based on the synchronization characteristics of chaos,the parallel current sharing control of voltage controlled Buck converter is realized and the current sharing effect of parallel system is improved.