Study Of Control For Fast-scale Bifurcation And Chaos In Power Electronic Circuits

Power electronic circuit belongs to the strongly nonlinear circuit system. Due to the non-linearity of the device and the switching function of the switch, a variety of nonlinear phenomena will occur in the operational process, which worsens many performances of the circuit.Through the research of the bifurcation and chaos control in the power electronic circuit, it can reveal the nonlinear nature of the circuit, improve varied performance indicators of the circuit, provide an effective guarantee for the stable operation of the circuit, and supply the theoretical basis for the design of the stability of practical circuits. The detailed contents are as follows:(1) The paper introduces some basic knowledge related to the chaotic dynamics, which provides a theoretical guidance for the research of fast-scale bifurcation and chaos control in the power electronic circuit. Also, it points out the structure for the whole paper.(2) In this paper, we introduce some metods of the bifurcation and chaos control, and analyze their respective characteristics. Although many achievements have been made now, the chaos control is still a hot research field.(3) The fast-scale bifurcation control in the switching power converter has been researched deeply.The power electronic circuit has been widely applied in engineering practices. With the changes of some system parameters in the circuit, the bifurcation of the circuit will occur and then changes into the chaotic state, which degrades the performance of the system. In the actual project, we hope the circuit work steadily on the switching frequency to avoid any bifurcation and chaotic behavior. Slope compensation is a simple and effective way. It has good applicability and is suitable for bifurcations and chaos control in power electronic circuits. This paper starts from the theory of bifurcation control of nonlinear systems, and makes a detailed analysis of the slope compensation in several typical circuits under the peak current-mode control, and then comes to the optimal compensation results. The accurate simulation results verify the effectiveness and correctness of the theoretical analysis. This method is also applicable to the stability analysis and the design of other power electronic circuits.(4) The single and parallel single-phase SPWM inverters, wideley used in engineering practices, have been researched extensively. When system parameters change, the inverters will appear to be bifurcate and then go into the chaotic state, which degrades the performance of the system. Based on the theory of bifurcation control of nonlinear systems, the paper makes a detailed analysis of the slope compensation in the single and parallel single-phase SPWM inverters under the peak current-mode control, and then reaches the optimal compensation results. The accurate simulation results prove the effectiveness and correctness of the theoretical analysis. This method is also applicable to the stability analysis and the design of the power electronic circuits.(5) The delayed feedback approach is adopted to deal with the chaotic phenomena occurring in the more complex circuits in power electronic circuits, like single-phase SPWM inverter and PFC Boost Converter. The chaotic phenomena get effective control and achieve the transformation of the periodic state from the chaotic state to the steady state. The results of the control make the system back to the unstable periodic orbits (UPO) in the chaos of the original system. Through a large number of simulations, we summarize how the different feedback gainK1and different delay time r influence the system performance and how the circuit parameters affect the feedback gainK1, so as to provide a reliable theoretical guidance for the design of the circuit stability.