Sliding Mode Variable Structure Control Of DC-DC Buck Converter System Based On Dynamic Disturbance Compensation

Due to its low cost and high reliability,the DC-DC buck converter is widely used in power electronic systems.With the continuous expansion of the application and research fields,the performance requirements of DC-DC buck converter are becoming more strict,and there is an urgent need to improve the speed of system response and tracking performance.However,in actual control engineering,there are factors such as parameter perturbation,load mutation,measurement noise,and external disturbances that make it difficult for the DC-DC buck converter to achieve the desired performance.Therefore,in order to improve the control performance and robustness of the DC-DC buck converter,and ensure its quality of the output voltage,it is of great practical significance and application value to propose a robust control design method for the DC-DC buck converter system.This dissertation presents an dynamic disturbance compensation method based on sliding mode control is proposed to improve the robustness and tracking tracking performance of the DC-DC buck converter system.The research work mainly includes the following three aspects:(1)A robust control method based on nonlinear active disturbance rejection control is proposed for DC-DC buck converter system with variation of input voltage and load resistance.Considering the lumped disturbance,which contains variation of input voltage and load resistance,as a new state variable,the integral-chain state space model is established.A standard extended-state-observer(ESO)is constructed to estimate the state and lumped disturbance of the system in real time.The disturbance is compensated dynamically by a nonlinear feedback control law,and a tracking-differentiator is used to arrange the transition process performance of the system,and to eliminates trade-off between the system output response overshoot and rapidity.Finally,compared with the PID-based DC-DC buck converter system,the designed system can track the reference input voltage quickly,without overshoot and ripple in the presence of input voltage and load resistance mutation.(2)For the general forms of DC-DC buck converter system,a equivalent-inputdisturbance(EID)-based sliding mode control method is proposed.By formulating the influence of the load resistance variation on the system as the effect of input disturbance on the system,a state observer is established to estimate this equivalent input disturbance.Then,the estimated value is fed back to the system input to eliminate the disturbance.It effectively solves the chattering problem which is caused by the approaching gain is too large in sliding mode controller.According to the small gain theorem,the system stability conditions are obtained,and the separation design procedures of the EID estimator and sliding mode controller are given.Compared with the linear standard ESO-based DC-DC buck converter system,the disturbance rejection ability of the proposed system is verified,and the proposed method is more widely used and suitable for non-integral cascade model.(3)For DC-DC buck converter system subject to mismatched disturbance,a generalized ESO-based sliding mode control method is designed.After analyzing the influence of disturbance on the system output voltage,a DC-DC buck converter sliding mode control system structure based on generalized ESO is constructed.By treating the mismatched disturbance in system as a new state variable,a generalized ESO is applied to estimate the original state of the system and mismatched disturbance.By selecting a suitable dynamic disturbance compensation gain,a composite control law based on disturbance dynamic compensation and sliding mode variable structure control is constructed.It effectively eliminates the influence of parameter perturbation on the system output.According to the small gain theorem,the system stability conditions are obtained,and the separation design procedures of the generalized ESO and sliding mode controller are given.Through numerical simulation analysis,it shows that the state of the proposed DC-DC buck converter system of can converge to the desired equilibrium point,and it has satisfactory transition process performance,steady state performance and robustness.