| DC/DC converter is a typical strong nonlinear system.Nonlinear dynamical phenomena such as bifurcations and chaos are often exhibited when the circuit parameters are out of certain region,which can deteriorate the converters' performances,such as low voltage set-up ratio,large ripple of state variables.Therefore,it is necessary to control the converter from the chaotic state to the steady state in order to improve the performances of the converter without changing the topology and the parameters of the converter,which is the main purpose of this thesis.In this thesis,the stroboscopic mapping model of the peak current-mode controlled Boost converter is established and the nonlinear dynamic behaviors are analyzed.Then the basic principle of parameter-perturbation method is introduced,and a chaos control strategy based on target orbit control method is adopted.It is shown from the numerical simulations that the Boost converter can return to stable period-1 operation from chaotic state.A higher voltage set-up ratio could be acquired,and meanwhile the stability and dynamic performance of the system are improved.Compared with the commonly used slope compensation technology,the control strategy in the thesis presents a better control effect.Then the method based on target orbit control is extended to a typical high set-up ratio DC/DC converter,which is the switched inductor Boost converter.It is shown from the numerical simulations that voltage set-up ratio is further improved,ripples of inductor current and output voltage are reduced at the same time.Finally,the thesis takes the Boost converter as an example,a hardware experimental system based on chaos control method is established on the STM32 platform.The design of hardware circuit and software program,hardware and software debugging are completed.Experimental results agree well with the simulations and theoretical analysis,which confirms the effectiveness of the proposed control method. |
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