Research On Sliding Mode Control Method Of DC-DC Buck Converter Base On DSPACE

DC-DC converter has been widely used in practical scenarios such as new energy generation,smart phones and medical devices because of its low cost and simple topology.The existence of switch leads to strong nonlinearity of DC-DC converter,which increases the complexity of its control.Sliding mode control,as a typical non-linear control method,can be adjusted quickly in the control process,and is less affected by external interference.It is applied to motor speed regulation and converter control system.In this paper,DC-DC buck converter is taken as the research object,and using state space average to build its model.Around the problem of control system accuracy and resistance to load disturbance,a single-loop sliding mode control strategy based on load estimator is proposed.The estimator is used to estimate the load of the buck converter and the estimated value is used to construct the sliding mode controller.Secondly,aiming at the problem of low steady-state error and control precision caused by chattering in single-loop sliding mode control,a dual-loop control structure is adopted.The buck converter is divided into voltage loop and current loop,and the controller is designed for each loop.Based on this,a cascaded double-loop second-order sliding mode control strategy based on load estimator is designed.The controller based on Super-Twisting algorithm is used to ensure the tracking of the output voltage.The load parameters are estimated by the output of the estimator;the inner current loop is designed to track the inductance current by the output of the outer current loop as its expected current value.Finally,for the two control strategies designed,the feasibility is verified by simulation,and then the hardware-in-the-loop simulation platform is built by using dSPACE realtime simulation system to verify the actual effect of the control method.Compared with cascaded double-loop PI controller,the cascaded double-loop second-order sliding mode controller based on load estimator has the best dynamic characteristics and antiinterference performance.