Research On Linear Active Disturbance Rejection Control Strategy Of Dual Active Bridge DC-DC Converter

Isolated dual active bridge DC-DC（DAB）converter has many advantages,such as bidirectional power flow,high power density,easy implementation of zero voltage switch,convenient cascade and parallel processing.Therefore,the converter is widely used in distributed power generation systems,DC microgrid systems,electric vehicle charging systems,etc.DAB converter plays a connecting role in the system.Its control effect will directly affect each link of energy conversion system.Therefore,the robustness control of DAB converters is also concerned by many scholars.In this paper,DAB converter in the new energy DC conversion system is taken as the research object,and the stabilization of DC bus voltage is taken as the research objective.First,the application prospect and topological structure of DC-DC converter are introduced in detail.Then,six working modes of DAB converter under single phase shift（SPS）control mode are analyzed in detail In this paper,the mathematical model of the converter is deduced by the small signal modeling method,and the single voltage closed-loop control is designed.In order to improve the robustness of the converter,the controller is optimized based on the above mentioned.An improved LADRC strategy is proposed to solve the problem that the traditional linear active disturbance rejection control（LADRC）has poor observation ability to total disturbance.The differential signal of total disturbance is expanded into a new state variable and applied to the controller of DAB converter,which significantly improves the observation performance of the observer and improves the dynamic response and robustness of the converter.Finally,the advantages of the improved LADRC controller are verified on MATLAB/Simulink simulation platform.In view of the dependence of traditional direct power control on the model,this paper combines linear active disturbance rejection control with direct power control and proposes a new active disturbance rejection-Direct power control strategy（ADR-DPC）.The internal system parameters in the traditional power controller are omitted,and linear extended state observer（LESO）is used to observe and compensate system uncertainty and disturbance in real time,which solves the dependence of traditional direct power control on system parameters and improves the disturbance rejection capability of the system.Finally,the DAB converter model is built on MATLAB/Simulink simulation software.The effectiveness of the proposed control scheme is verified by designing different working conditions on the power side and the load side.