Research Of Bifurcation And Chaos In Single-phase Full-bridge Inverter

Power electronic system, which belongs to the typical nonlinear system, consists ofa large number of switching devices. In some conditions, a series of nonlinear dynamicsbehaviors, such as bifurcation and chaos, appear in the system, which will seriouslyaffect its security and stability. Therefore, the nonlinear kinetics study of powerelectronic system has become an important branch of power electronics. Inverter is acore power electronic device, so its stability concerns the overall performance of thesystem. The single-phase full-bridge inverter is researched in this paper. Bifurcation andchaos appeared in the system are studied intensively, which aims to optimize theparameters of system design, extend the stability domain, and improve the dependabilityof system. The main contents of this thesis are as following:①The single-phase full-bridge inverter in stand-alone mode is studied in this paper,and the nonlinear dynamics model is founded by stroboscopic sampling method. By themethods of bifurcation diagram, Jacobian matrix, Lyapunov exponent, bifurcation andchaos during the system are analyzed from the view point of single-parameter andmulti-parameter, which reveals the relationship between the operation condition and thebifurcation parameter. Then, the stability parameter domain of system is obtained,which can provide the reference and instruction for the design of the practical system.②The bifurcation and chaos during the inverter with PI controller is alsoresearched in detail. Discrete model of the system is deduced from the transfer functionof PI controller. With the change of input voltage, the evolutionary process of therunning status is analyzed by bifurcation diagram. By means of the folded diagram andexperimental circuit, the stability parameter felid of system is validated.③In view of the limitation about stroboscopic sampling method, which has lowsimulation speed and occupies great memory space when used in high order system, acoefficient linear discrete model, based on some improvement, is presented in this paper.The two order inverter casing is used to prove that, not only can the new modelguarantee precision, but improve the simulation speed and take minimal memory space,which is an efficient modeling method.④This paper popularizes the nonlinear kinetics study into grid-connected inverterwith LCL filter, and the discrete model is also derived. The stability of system is studiedby Jacobian matrix, which came to the conclusion that a pair of characteristic value corresponds will cut across the unit circle in conjugate complex form, when the systemparameters are under certain conditions. Simulation and experiment results indicate thatHopf bifurcation appeared in the system.⑤Aiming at the irregular behavior in H-bridge converter, Washout filter is broughtin chaos control, and the discrete Washout filter is designed. The bifurcation and chaos,appear under the two modes of H-bridge, is controlled effectively. Meanwhile, thecontrol performance is compared with Time-Delayed Feedback Control(TDFC) method,which conclude that the control method of Washout filter, possessing certainanti-interference, is an efficient chaos control method.