Research On Buck Type DC-DC Converter Control System Based On Finite-time Control Technique

Buck type DC-DC power converter(Buck converter)is a power electronics which can change voltage of direct current.Buck converter is widely applied to drive of direct current motor,computer systems,medical electronics,communication equipments,and so on.Buck converter is a typical switching system.In practical engineering,magnetic properties of inductor is usually uncertain and time-varying.Disturbance of load variation also influence close-loop system stability.Because buck converter has the above characteristics,the control problem is challenging and has practical significance.It is difficult to achieve better control performance based on traditional linear control methods.Therefore,more and more attentions are paid to design nonlinear controllers.Most of existing results about non-linear controllers only guarantee that the closed-loop system is asymptotically stable.For control system,if the state of system can be controlled to convergent to the equilibrium point in a finite time,e.g.,finite-time stability,it can obviously improve the convergence performance of the system.In this paper,the control system of Buck converter is designed mainly based on the finite time control theory.The main work is given as follows:(1)The work principle of buck converter is analyzed.State space equation of buck converter is established based on average state space theory.Based on PSIM software,the simulation platform of Buck converter control system is established.Based on TMSF28335 series DSP and buck converter,the hardware experimental platform is built.(2)A new class of adaptive finite-time control algorithm is designed for buck converter.Firstly,based on time-scale transformation,the coordinate transformation of buck converter model is carried out.Then,based on state feedback,a class of finite-time feedback controller is designed to guarantee that output voltage can track the reference voltage in a finite time.Based on finite-time observer technology,a load estimator is designed to improve system's anti-disturbance ability.The system parameters can be identified by the designed load estimator in a finite time.Rigorous theoretical proof,simulation,and circuit experiment are given to prove the effectiveness of designed control algorithms.(3)A class of finite-time output feedback control algorithm is designed for buck converter.Firstly,for average state space model of buck converter,based on finite-time observer technology,the inductor current estimator is designed.Then,based on output of inductor current estimator,an output feedback finite-time control algorithm is given to observe current state in finite time.Finally,rigorous theoretical proof,simulation,and circuit experiment are presented.(4)Based on hardware verification platform of buck converter,the proposed control algorithm is verified by a series of experiments,including adaptive finite-time control algorithm and finite-time output feedback control algorithm.The experimental results verify the effectiveness of the proposed control algorithm.