| The DC-DC converter plays a central role in the switching power supply,and it is very strong because of its strong nonlinear system.In the actual operation of DC-DC converter,there are some strange or irregular phenomena such as unknown noise,electromagnetic interference and subharmonic oscillation.These phenomena will lead to some electrical equipment can not run normally.Therefore,with the requirement of DC-DC converter operating performance continues to improve,the mechanism of using the dynamic theory of the nonlinear behavior of converter produced are analyzed deeply,has a very important significance.Firstly,this paper introduces the basic theory and basic types of nonlinear phenomena in DC-DC converter,the operation of PWM DC-DC converter during the unstable period doubling bifurcation and chaos phenomenon leads to a variety of ways,the establishment of nonlinear dynamic model of DC-DC converter in reason and chaos these bifurcations are studied in detail,and the current research situation of converter control strategy and control technology of DC-DC is discussed.Secondly,this paper is based on the voltage mode Buck converter as an example,the theoretical basis is the basic of its state equation,establish the piecewise smooth switch model and using simulation software Matlab/Simulink,so as to obtain the corresponding Buck converter phase diagram and time-domain waveform;through the stroboscopic mapping way of sampling of voltage mode converter that established the precise discrete iterative map model,and in the Matlab M file is written,so as to obtain discrete output voltage and inductor current value.At the same time,the simulation results of the two models are combined together,which proves the existence of bifurcation and chaos in the voltage mode Buck converter.Finally,in view of the instability of the voltage mode Buck converter,such as electromagnetic interference,output ripple,etc..In this paper,the proportional integral control method and the external drive control method are used to restrain the bifurcation and chaos of the converter.By proportional integral(PI)control method through adjusting curve parameters and bifurcation point,scale factor stability the high-frequency behavior of the system mainly depends on the PI regulator,so the voltage mode Buck converter of bifurcation control.If the sensitivity parameters of the system change,the drive control method is adopted to adjust the amplitude and phase of the control signal,so that the system can achieve an optimal nonlinear control results.Based on DSP(digital signal processing),this paper presents an experimental platform for the chaos control of voltage mode Buck converter,and further verifies the feasibility of the method.At the same time,it provides a new idea for the hardware design of the converter. |
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