Investigation On The Dynamical Behaviors Of DC/DC Converter With Memristive Load

DC/DC converter has been widely used in various fields due to the advantages of simple topology,easy implementation and high efficiency.For power electronic equipment,stability and reliability are the basic requirements for system operation.However,the circuit may generate complex nonlinear phenomena while the parameter changes,which will cause the system instability or failure.Therefore,the topic of nonlinear dynamics in DC/DC converters has caused much attention.However,the current research on DC/DC converter is mainly based on the traditional load such as resistor,power supply or motor,etc.As the fourth electrical component in addition to resistor,inductor and capacitor,the academe has surged to do the research into memristor at home and abroad since it was born in 2008.But there is no literature considering the DC/DC converter with memristance load up to now.Therefore,the memristor is applied to DC/DC Boost converter in this thesis.The influence of different control methods and memristor on converter's dynamical characteristics is studied.The major work and conclusions of the present thesis are as follows:Firstly,the chaotic dynamics of peak-current-control DC/DC Boost converter with memristance load is studied.When the memristor works in the passive region,the system dynamic behaviors changes from chaos to period with the increasing of the clock period.Different from resistance load,the output voltage no longer changes monotonously with the switching action,and it oscillates in a curved manner.Thus,a single scroll attractor is generated.The dynamic characteristics of the circuit are analyzed from a new point of view by using duty cycle.It is found that the memristance load circuit can work stably when the duty cycle is greater than 0.5,but the resistance load circuit cannot.In addition,it is found that the output voltage and flux always oscillate near the quiescent point.When the different disturbances are input,the results show that the introduction of memristor does not reduce the stability of the circuit.According to the practical component model,the experimental circuit of DC/DC Boost converter with memristance load is established for the first time in the international circuit simulation platform NI Multisim.The new,different dynamical phenomena are captured through experiments.It is verified that the output voltage and flux always converge to the quiescent point,and they are not affected by the operating state of the system.It also proved that the activity of memristor is not necessary for DC/DC Boost converter to generate chaos.The experimental results are in agreement with the theoretical and numerical results.Secondly,the output voltage is added as a feedback control variable,and the chaos and subharmonic oscillations of DC/DC Boost converter with MR(Memristor,Resistor)load under the voltage-current closed loop control are studied.It is found that chaos and subharmonic oscillation occurs alternately with the changing of clock period when the memristor works in the passive region.Moreover,when the voltage feedback loop control is added,the output voltage of the circuit is no longer a curved oscillation,but changes monotonously with the switching action.The attractor is serrated under the influence of the control method.The dynamic characteristics of the circuit are analyzed from a different angle by using the duration of inductor discharge.Besides,the ripple of the output voltage is very small,and it's independent with the dynamic behaviors.If other parameters are fixed,the output power increases with the increasing of the sawtooth period.The experimental circuit is established according to the practical component model.Chaos and subharmonic oscillation are observed in the experiment,and the above-mentioned nonlinear dynamic characteristics are verified.At the same time,it is proved that the output voltage varies monotonously with the switching action,and the variation of inductor discharge duration is consistent with the dynamic behavior of the system.Finally,the above studies are done when the memristor works in the passive region,but the active region of memristor are not considered.Therefore,the multi-stability of the DC/DC Boost converter is discussed when the memristor works in the active region.The third-order nonlinear switching model with the parasitic resistor of inductor is reconstructed.It is found that the system exhibits different dynamic characteristics and different bifurcation paths under different bifurcation parameters.The coexistence attractors are excited by different initial conditions,and the independent attraction basins of the initial condition for coexistence attractors proved that the circuit is multistability.The characteristics of the attractors are analyzed from a different angle by using the extreme point method,which is simpler and more intuitive than the Poincaré section.The output voltage is no longer controlled by memristor parameters when the equations of constitutive relation and internal state are nonlinear.According to the practical component model,the experimental circuit is established,and the coexistence attractors are captured in the experiment,which proves that the circuit is multi-stability.