Research On Chaotic Phenomena And Chaotic Control Of PWM DC-DC Converter

The chaotic phenomenon which occurs in the deterministic system is the irregular movement which is seemingly random. Moreover, the chaotic phenomenon is the inherent property and the common phenomenon of the nonlinear system. The PWM DC-DC converter is a strong nonlinear system. Under certain parameters conditions, the converter will appear the chaotic phenomenon. In the actual physical environment, the chaotic phenomenon of the converter is the unknown electromagnetic noise, the amplitude of the voltage and the current jumping largely, the operating performance worsening and so on. Thus, in the converter designing, reaserching on the chaotic phenomenon and the chaotic control of the converter helps us avoid or inhibit the chaotic phenomenon and makes the converter operate in the stable periodic state, which has the important significance for the converter designing and debugging.Based on the Boost converter and the Buck-Boost converter which are widely used, the chaotic phenomenon and the chaotic control are studied. Firstly, the accurate state equation model and the discrete map of the Boost converter are established. Based on the above mathematical model, the bifurcation map, the Poincare section, the output voltage waveform diagram, the phase diagram and the incomplete period-doubling Feigenbaum tree of the Boost converter are studied by the MATLAB simulation.Secondly, the accurate state equation model and the discrete map of the Buck-Boost converter are established. Based on the above mathematical model, according to the reference current, the input voltage, the resistance, the inductance and the capacitance which work as bifurcation parameters respectively, the time-domain waveform diagram, the switch logic, the phase diagram, the Poincare section, the bifurcation map and the periodic window are simulated.Thirdly, based on the linear feedback control theory, the linear self-feedback control method is studied and applied to the Buck-Boost converter. When the reference current works as the bifurcation parameter, the chaotic Buck-Boost converter is controlled to1、2、3、4、6、8periodic orbits; when the input voltage works as the bifurcation parameter, the chaotic Buck-Boost converter is controlled to1、2、4、8、12periodic orbits.Fourthly, because of the big feedback gain of the linear self-feedback control method, the nonlinear piecewise quadratic function feedback control method is studied, that is to say, adding a nonlinear feedback controller which is a piecewise-quadratic function in the form ofχ|χ|into the chaotic Boost converter and the chaotic Buck-Boost converter. The chaotic converter is controlled to diversified periodic orbits by adjusting the feedback gain in the nonlinear feedback controller. The simulation result shows that the nonlinear piecewise quadratic function feedback control method has the smaller feedback gain and the simple structure.