Research On Finite-time Control Of DC-DC Converter Based On Sliding Mode Method

As a kind of commonly used electric device, DC-DC converter can realize the function of voltage regulation by converting direct voltage of the system input into any reference value fast and effectively, and with the advantages of high energy utilization ratio and low cost, it has been widely applied in many areas. But the systems with disturbance or nonlinear load always bring undesired output characteristics, bad anti-disturbance capability and low control precision.Therefore, how to improve the output characteristics of DC-DC converter has been the focus of related research. The Finite-time control systems have fast response speed, high control precision and good anti-disturbance capability. In order to strengthen anti-disturbance ability and improve the output characteristics and the control precision of DC-DC converter, this paper respectiely design a exponential teminal sliding mode controller for Buck conventer, and a teminal sliding mode controller based on the backstepping method for Boost conventer. Finally, the validity and correctness of these control srategies are testified through computer simulation. This paper contains as follows:The basic theory of two typical DC-DC converters-Buck converter and Boost converter are analysed and the mathematical models are given. Firstly, we get mathematical modes based on state-space averaging method. Then, in order to facilitate the controller design, by using circuit characteristics and exact feedback linearization method, convert them into Lower Triangular form.In order to improve the anti-disturbance capability and output characteristics of Buck converter, weaken chattering phenomena of controller and accelerate the system response speed, based on the theroy of Finite-time control and exponential terminal sliding mode control, a novel control law is proposed, which not only effectively solve output mutations problems of traditional controller, but also greatly improve anti-disturbance capability, and also accelerate system response time and improve system output characteristics.Boost converter based on integral sliding mode control has some limitations including bad output characteristics and serious high frequency chattering. Therefore, a terminal sliding mode controller based on Finite-time control is designed by using backstepping method. The simulation results show that this controller can not only greatly weakened the high frequency of controller chattering, but also improve the system output characteristics.