Research On Driving Integrated On-board Charging System Based On Dual Active Bridge Converter

In the national ’double carbon’ policy requirements,electric vehicles become the mainstream of the automotive market,which also put forward higher requirements for electric vehicle technology.Battery charging technology profoundly impacts charging efficiency of electric vehicles,and motor drive technology is directly related to the user’s driving experience.Both controllers occupy a lot of space inside the electric vehicle,raising the weight of the vehicle.Based on the traditional electric vehicle on-board charger,this thesis extends the function of the on-board charger by multiplexing the three-phase bridge full-control circuit into an interleaved parallel totem pole power factor correction(PFC)circuit and a three-phase inverter circuit in the form of a bidirectional AC/DC converter,so that it can also realize the control of the motor.The DC/DC converter part realizes the energy exchange from the power supply to the battery or the battery to the motor through the dual active bridge(DAB)converter.The main circuit structure of the drive integrated on-board charging system and the two working modes of charging and driving are described in detail.On the basis of fully grasping the working principle of the front and rear circuits,the working characteristics of the front circuit and the soft switching range of the rear circuit are explored.On this basis,the mathematical model of the pre-stage and post-stage circuits is built by small signal analysis,and the control strategy of the pre-stage double closed loop and the post-stage double loop competition is formulated.The PI controller parameters are designed by using the built mathematical model,and the stability of the compensated system is verified by drawing the open-loop amplitude-frequency characteristic curve.According to the system parameter index,the parameters of the energy storage element are reasonably designed,and the simulation model of the driving integrated charging system is built in Simulink with the corresponding control strategy.The rationality and effectiveness of the control system design are verified by the realization of the PFC function and phase shift control in the charging mode simulation and the fast response of the motor in the driving mode simulation.The experimental platform of driving an integrated on-board charging system with TMS320F28335 as the core control chip is built.The effectiveness of the charging mode is verified by using an electronic load and high-voltage DC source to simulate a power battery,and the effectiveness of the driving mode is verified by using a 5k W permanent magnet synchronous motor.The experimental results show that the drive integrated on-board charging system can realize the functions of charging and motor driving,thus verifying its feasibility.