Research On DAB Converter Based On TPS Control System

With the rapid development of the global economy,the lack of fuel has become a major concern for countries around the world.The transformation of energy structure from clean energy to electric energy has become a top priority,which puts high demands on the transmission and storage of energy.Among the many isolated bidirectional DCDC converter topologies,dual-active-bridge converter has become a popular topic of research because of its symmetric structure,soft-switching characteristics,flexible control mode and other good performance.However,the overall optimization strategies for inductor current stress and soft-switching range still need to be improved.In addition,the traditional PI control method is still inadequate in terms of dynamic performance.This thesis focuses on full-bridge dual-active-bridge converters and uses triple-phase-shift control method as the phase shift control,studied and improved on the above issues.This thesis proposes a direct power control with sliding mode control method based on triple-phase-shift minimum inductor current stress optimization strategy to optimize the traditional PI control method,which can optimize both the steady state performance and dynamic performance of the converter.Firstly,Lagrangian multiplier method combined with Caro required-Kuhn-Tucker condition is used to obtain a phase shift ratios combination that satisfies the minimum inductor current stress,which also satisfies the soft switching condition.Secondly,the dynamic equation of the output voltage is obtained by the reduced-order model of the DAB converter,and the slidingmode control function is further obtained,which can return to the new status as quickly as possible when the system status is changed by the design of the sliding-mode surface and the convergence law.Finally,according to the idea of direct power control,the control function is used to invert the phase shift ratios to modulation.In this thesis,the proposed method is compared with the conventional PI control method in terms of steady-state performance and dynamic performance by building a MATLAB/Simulink simulation platform and a hardware circuit experimental platform.The results show that the steady-state inductor current stress of the proposed method is lower than that of the single phase shift control,and the dynamic response time of the proposed method is shorter than that of the traditional PI control method when the reference output voltage changes,which verifies the feasibility of the theory.