Research On Application Of Model Predictive Control In Dual-Active-Bridge Converters

The battery management system has the characteristics of bidirectional energy transmission and requires a bidirectional DC-DC converter to connect the DC bus and the battery pack to ensure the bidirectional transmission of electric energy.The Dual-ActiveBridge converter is a bidirectional isolated DC-DC converter,which commonly used in battery management systems.Dual-Active-Bridge converter are flexible control,and easy to accomplish soft switching.However,the Dual-Active-Bridge converter has many controllable variables,so it is complicated to control Dual-Active-Bridge converter。 The converter performance is not good when the traditional closed-loop control is used.Model predictive control is a new type of control method based on predictive models that solves an open-loop optimization problem online to obtain the optimal control output,and act on the system.This article focuses on the research on the control method of the DualActive-Bridge converter.Based on the model predictive control,a hybrid Phase-Shift optimization control method is proposed,which reduces the loss and improves the efficiency.Firstly,the article analyzes the working principles of Dual-Active-Bridge converters under Single-Phase-Shift control,Dual-Phase-Shift control and Triple-Phase-Shift control.The duty cycle range of all switching tubes under these Phase-Shift modes to achieve soft switching are calculated.Next,this paper calculates the relationship between the effective value of the inductor current and the duty cycle of the Dual-Active-Bridge converter under Dual-Phase-Shift control and Triple-Phase-Shift control,and calculates the conditions for achieving the minimum inductor current.Since DAB converters cannot achieve effective soft switching at the critical point in Dual-Phase-Shift control,a critical point frequency hopping method to solve the soft switching problem in the full power range is proposed.Finally,by arranging the above optimization methods,a hybrid PhaseShift optimization model was obtained,which achieved the optimization goal.In order to verify the feasibility of the hybrid Phase-Shift optimization model,this paper uses MATLAB-Simulink software to build a model using MATLAB Function module and conduct simulation verification.The results show that the hybrid Phase-Shift optimization model can realize the soft switching of all switching tubes in a wide output voltage range and full power range,and at the same time the effective value of the inductor current is smallest.Compared with traditional PI closed-loop control,model predictive control has the advantages of rapid response and no static errors.