| DC-DC converter is a typical non-linear system and it will enter into chaos under certain condition.Due to the low level of the development of modern science and technology,DC-DC converters operating in chaotic state can’t be used to achieve some desired goals yet except being used to reduce electromagnetic interference and to improve the electromagnetic compatibility of power electronic device.However,once DC-DC converter enters into chaos,its output will become extremely unstable and the ripple will increase a lot,therefore,the quality of the output is very bad.Because of the reason above,the chaos occurring in the DC-DC converter is supposed to be suppressed.For the chaos occurring in the representative of the non-isolated DC-DC converter—Buck-boost converter and the chaos occurring in the representative of the isolated DC-DC converter—two-transistor Forward converter,this paper presents the self-controlling delayed feedback control method and the sliding mode control method to suppress it.First,this paper deduces the discrete iteration model of the voltage mode controlled Buck-boost converter and the voltage mode controlled two-transistor Forward converter,respectively.Then based on the discrete iteration model,the chaos occurring in the converter with the voltage feedback coefficient k changing is been thorough analysed through the bifurcation diagram,the Jacobian matrixeigenvalue of the discrete iterative formula,the Lyapunov exponent,the mixed second partial derivative of the discrete iterative formula and the simulation.Next,the self-controlling delayed feedback control method and the sliding mode control method are introduced to control the chaos occurring in the voltage mode controlled Buck-boost converter and the voltage mode controlled two-transistor Forward converter with k changing,respectively.The simulation results show that the dynamic response speed of both control method is fast and both control method can force the converter to operate stably in one-cycle state.The self-controlling delayed feedback control method doesn’t change the switching frequency of the system.Besides,it can just use one feedback control coefficient k1 to control the system with different voltage feedback coefficeient k.However,this method has certain limitation.The sliding mode control method compensates for the limitation of the self-controlling delayed feedback control method and it has excellent robustness.At last,this paper studies the chaos occurring in the voltage mode controlled Buck-boost converter with other basic circuit coefficients—E,L,C and R changing based on the controlling variable method and introduces the sliding mode control method which has better control effect and wilder application range to achieve chaos control.The simulation result shows that the sliding mode control method can validly suppress the chaos occurring in the voltage mode controlled Buck-boost converter with each coefficient changing,respectively,meanwhile,the dynamic response speed is fast.In addition,the ripple of the voltage and the current is small after introducing the sliding mode control method. |
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