Study On Nonlinear Behaviors And Chaotic Control In Switched-inductor Boost Converter

With the continuous application and development of the green energy likephotovoltaic power generation system and fuel cell, high gain DC/DC converter hasbecome the research focus of scholars at home and abroad. For this reason, theswitched-inductor (SI) boost converter is proposed. This converter not only can providehigh voltage transfer ratio, but also can reduce the current stress and votage stress of theswitching devices, reduce loss of the circuit and improve the efficiency of the system,which is a new kind of topology that has a broad application prospect. However, thisnew converter is a strongly nonlinear system because of the existence of the switchingelements, its running state can be easily influenced by the circuit parameters, theresulting bifurcation and chaos phenomenon will seriously affect the normal operationof the equipment. Therefore, it is meaningful for improving the stability of the system tostudy on the nonlinear behaviors in this new converter by using the theory of nonlineardynamics. And it is also useful to take effective control strategy for inhibiting the chaosin the system.Firstly, the SI boost converter under current mode control is chosen as the researchobject. Its discrete iterated mapping model under continuous conduction mode (CCM)is established. The type of bifurcation point and the region of stable parameter aredetermined by using bifurcation diagrams, Lyapunov exponent, Poincare section and theeigenvalues of Jacobian matrix. As a result, a special phenomenon called bifurcationtrajectory intersection that doesn’t exist in the traditional Boost converter is found. Andthe simulation module of the system is set up through the PSIM software, which verifiesthe correctness of the numerical simulation results.In order to satisfy the application conditions of the large capacity situation, two ormore than two switch converters are often combined together in the practicalengineering application, forming a parallel system, but the research results ofits nonlinear behaviors are rarely reported. Therefore, this paper then takes the multi-parallel-connected SI boost converter as an example, and its nonlinear dynamiccharacteristics are researched deeply by numerical simulation and PSIM simulation. Theresults prove that the more number of the parallel-connected converters, the system willmuch easier to come into chaos.In order to control the chaotic SI Boost converter into periodic orbits, the methodsof both resonant parametric perturbation and slope compensation are applied to controlthe chaos in current mode controlled SI Boost converter. And the principles of the twokinds of control method are analyzed by theoretical derivation and numerical simulation.Then, the simulation model of the chaotic control system is established in PSIMsoftware, and its results confirm the effectiveness of the proposed control method. Finally, the experimental platform is set up. The complex and diverse nonlineardynamic behaviors in SI Boost converter and its multi-parallel-connected system areverified from a practical point of view. At the same time, the experiment results confirmthat the chaotic system can be controlled into different periodic orbit with the method ofslope compensation.The results of this article have important guiding significance for parameteroptimization and stability analysis of SI Boost converter and its multi-parallel-connected converter system.