Research On Buck DC-DC Switching Power Based On Sliding Mode Variable Structure Control

With the advent of the new energy era,switching power have become an indispensable part of the power supply system of electrical devices with the advantage of high conversion efficiency,and are widely used in communications,military,aerospace and other major fields.How to control the switching power supply system to obtain high-performance output response has become one of the research hotspots in the field of power electronics.This paper takes Buck DC-DC switching power as the research object,proposes a nonlinear sliding mode variable structure control algorithm,and on this basis,proposes a control algorithm with improved performance,which makes the system insensitive to external parameters and strong antiinterference and good robustness.Considering that the actual Buck DC-DC switching power system will be affected by system parameter disturbances,external noise and other factors,a mathematical model containing disturbance terms is established on the basis of analyzing the working principle of the circuit.Designed double closed-loop control architecture with the voltage outer loop sliding mode variable structure controller and current inner loop PI controller.In the optimization of sliding mode variable structure control algorithm,a composite sliding mode variable structure control algorithm is designed by combining the neural network and the relevant theoretical knowledge of the disturbance observer.In view of the neural network has the advantage of better fitting nonlinear functions,the classical radial basis function network and the extreme learning machine are used to adaptively approximate the uncertain disturbance term in the Buck DC-DC switching power system model and design control law.Based on the ideal estimation of the system’s lumped disturbance by the disturbance observer,a control law containing disturbance estimation compensation terms is designed.According to the design of the control architecture and control algorithm,a simulation circuit model is built in the PSIM environment for simulation,and the DSP TMS320F28335 chip is used as the control core.The experiment is carried out on the hardware experimental platform.The experimental results show that the proposed three composite control algorithms have faster tracking speed,better stability effect,and stronger robust performance compared with the traditional sliding mode variable structure control algorithm.In the compound control algorithm,the steady-state error is as low as 0.21%,which is lower than the traditional sliding mode variable structure control algorithm0.25%,indicating that the compound control algorithm can effectively suppress chattering.