Study Of Chaos Phenomenon And Control In DC/DC Converter

The phenomenon of chaos by a series of bifurcation in the DC/DC converter iscomplicated nonlinear dynamic problem, while the mathematical modeling andsimulation modeling of this problem are lacked in systemtic and intuitive. In addition,the existing chaos control strategies of this converter system are inaccurate or difficultin controlling the closed orbit back to the stable orbit. The DC/DC converter is widelyapplied in industry. when it appears chaotic behavior with parameter variation, thesystem will result in high noise amplitude and unstable behavior, which will worsen theperformance of the converter. With the demands on the performance of the DC/DCconverter increasing, the thorough understanding about the mechanism of the chaosphenomenon in that system and the research of the better chaos control strategies haveimportant practical significance. Therefore, the research is launched from these twoaspects in this paper.First， the chaos research background, content and significance are brieflyintroduced. And then the current status and progress about the research of the chaosphenomenon and control in DC/DC converter are studied. The basic theory of nonlineardynamics of chaotic research is also studied after that.Second, based on the voltage feedback PWM Buck converter, the accurate discretemathematical model of this converter is systematically deduced and the periodic orbitproblem is deeply discussed. Taking the system Jacobian matrix eigenvalue as thejudgement basis, the load form a series stable periodic orbit bifurcation to chaos isdiscussed. In order to study the phenomenon of chaos in the Buck converter intuitively,the Matlab m function and the simulink circuit simulation module are applied to donumerical calculation and establish the circuit simulation model respectively. Thenumerical results are compared to the simulation results, which verify the correctness ofthe mathematical model and the above discuss.Finally, an improved OGY(Ott. E, Grebogi. C and Yorke. J. A)method—COGY(Continuous OGY) method is put forward to control the converterchaos, which converts the OGY discrete control signal into the continuous controlsignal. The functional expression of the COGY method is derived, and the blockdiagram of the control circuit is established. The numerical results are also compared tothe circuit simulation results, which verify the validity and superiority of this method. The precise control effect of the original method is preserved in the proposed method inwhich a continuous differential control signal is just needed while the samplingdifferential calculation on the Poincare return time is not to be needed. Additionally,compared to OGY pulse control sequence, the improved method can be more reliablebecause of the continuous control signal in this method.What’s more, the discussion and analysis in this paper could be adopted by otherpower converters similarly, which has definite reference value in the study of theconverter chaos.