Bifurcation Phenomenon And Bifurcation Control In DC-DC Converter

With the continuous development and application of green energy and products such as photovoltaic power generation system and new energy vehicles,the typical nonlinear behavior of DC-DC converters and its control technology have attracted wide attention.Scholars at home and abroad have also made fruitful achievements in the research of nonlinear behavior and control of switching converters such as bifurcation and chaos.Based on the previous research methods and the traditional voltage-type Buck converter as the research object,this paper proposes several new control strategies to suppress the nonlinear bifurcati on and chaos in the system.(1)The discrete mapping iteration model of the voltage Buck converter is derived based on the strobo-mapping method.The bifurcation diagram and phase trajectory diagram of the system are obtained by Matlab/Simulink numerical simulation.Based on the numerical simulation results,the accuracy of the theoretical analysis is verified and the nonlinear dynamic evolution law of the system with the change of the internal parameters of the circuit is obtained.Based on the stability analysis method of nonlinear theory,the stability of the system is analyzed deeply.Finally,a time domain circuit simulation model is built to verify the above analysis results.(2)Based on model(1),an improved passive time-delay feedback control strategy is added.The advantages of the proposed control strategy compared with the traditional control strategy are illustrated by the trajectory diagram of the characteristic values of the Jacobian matrix changing with the circuit parameters of the system,that is,the load capacity of the system is improved and the parameter design of the controller is more rapid and convenient.Finally,the simulation circuit model built by Simulink is used to verify the effectiveness of the proposed control strategy and the correctness of theoretical analysis.(3)In view of the limitation of the control strategy proposed in(2)under the load disturbance condition,two bifurcation and chaos control strategies are proposed,namely the sliding mode control strategy based on adaptive hysteresis modulation and the sliding mode control strategy based on LESO.Both of the two control strategies can effectively suppress the bifurcation phenomenon when the load side of the system is under large disturbance,and the latter can effectively avoid many problems in the control process of the former:(1)The adaptive hysteresis modulation is prone to small steady-state error when the load R is large;(2)Load reduction leads to the increase of the bandwidth of the sliding mode control system,which leads to the increase of the amplitude of the output voltage waveform and reduces the power quality of the system.(3)The instability of the system occurs when the load R decreases to a certain value.(4)When the power side and load side of the system are disturbed greatly,the system immunity decreases.To sum up,the research results of nonlinear behavior and control technology in switched converter system in this paper have very important reference significance for the design of actual power electronic switched converter circuit system.