Research On Regenerative Braking Control Strategy Of Pure Electric Semi-trailer

With the worsening of environmental and energy issues,pure electric vehicles,which symbolize new energy vehicles,are in greater demand.In the field of highway transportation,the pure electric semi-trailer of pure electric vehicles not only has the advantages of no pollution,low noise,convenient maintenance and other advantages,but also has the advantages of large cargo load and good economy of semi-trailer,which is the future development direction.However,the pure electric semi-trailer has drawbacks like inadequate range and poor safety and stability during braking.Applying a braking control strategy that includes regenerative braking function can improve both of the above issues.The regenerative braking function can reduce the energy dissipation during braking of the pure electric semi-trailer,while the braking control strategy can allow the vehicle to brake according to the driver’s intention and maintain safety and stability during braking through reasonable distribution of braking force.This research employs a pure electric semi-trailer as the objective model to develop a brake control technique that can implement the regenerative braking function.The main conclusions of the study are as follows:Taking driver-vehicle-condition as the research object,the braking control strategy of vehicle layer is designed,including the driver braking request identification function and the overall target braking force control function.The driver braking request recognition function can calculate the target deceleration of the entire vehicle,and the total target braking force control function can adjust the total target braking force to make the actual deceleration of the entire vehicle approach the target deceleration.Based on the analysis of the braking stability of semi-trailer,based on the existing braking force distribution strategy and combined with the actual requirements of engineering,a braking force distribution strategy for braking force recovery is designed,namely,a braking layer control strategy,which can realize the regenerative braking function while maintaining the safety and stability of braking.The designed control strategy is transformed into an operational algorithm model.According to the parameters of the target vehicle,the vehicle model is built in Truck Sim.Refer to relevant provisions in the national standards and related parameters of competitor models to establish appropriate performance standards.Based on these standards,design the relevant parameters of the drive motor and power battery,and complete the corresponding modeling in Simulink.Experimental validation of the braking control strategy was carried out using a test bench and a real vehicle.The braking control strategy was verified through hardware-in-the-loop testing.Compared to traditional PID control,the vehicle-level braking control strategy can reduce the difference between the actual and target deceleration by over 60% during the main braking process,and the overshoot during the control process is reduced by over 50%.The allocation-level braking control strategy can reasonably allocate braking force and achieve energy recovery during braking.During low-intensity braking,the braking force is allocated only to the front axle and trailer axle,while during medium-intensity braking,more braking force is allocated to the front axle of the tractor and trailer axle.The slip ratio of all axles during the braking process is less than 8%,with no risk of lock-up.Research shows that the regenerative braking control strategy designed in this paper has effectively realized the braking control functions at both the vehicle-level and allocation-level,and has certain application value.