Research On Dynamic Load Simulation Method Of Bus Powertrain

At this stage,most cities still use heavy-duty diesel vehicles as passenger cars,which have become a major source of urban pollution due to the large amount of exhaust emissions.Adopting a new power system is one of the most effective ways to solve the exhaust pollution of passenger cars.In the research and development of the power system,the indoor bench dynamic simulation test has become an important test method in the research and development process of the power system due to the advantages of short cycle,low cost and good test repeatability.The load simulation test bench needs to be able to dynamically restore the dynamic load received by the vehicle on the road in real time.Only when the load loaded by the bench and the actual driving load error of the vehicle are controlled within a certain range,the load simulation test is meaningful.How to improve the accuracy of load simulation has always been the focus of research on load simulation systems.Because the system has many factors that affect the accuracy of load simulation,such as model interference,torque interference,noise interference,etc.The development of a highperformance load simulation system is a challenging task.In this regard,this paper proposes a closed-loop torque and speed closed-loop control simulation method based on linear active disturbance rejection control(LADRC).First,based on the analysis of the advantages and disadvantages of the current load simulation method,the load simulation method of torque and speed closed compound control is adopted.In order to suppress the influence of the complex multi-source disturbance of the test platform on the load simulation system,the torque and speed closed compound control method is improved,and the robust LADRC algorithm is introduced into its dynamometer model speed regulator.Experiments have confirmed that the proposed method has good suppression of interference,indicating that the method can further improve the accuracy and robustness of the load simulation system.First of all,this paper analyzes the power system structure of a dual planetary hybrid bus,and designs its power system load simulation test bench on this basis.The model of the powertrain test bench is established on the Matlab/Simulink platform based on the modular modeling idea.It mainly includes power system component models,power system control strategies and load system component models.A basic simulation research experimental platform is proposed for the development,verification and optimization of the load simulation control algorithm in Chapter 4.Secondly,The longitudinal dynamics model of the vehicle is established based on the force analysis of the vehicle.The resistance mainly includes the time-varying resistance(air resistance,ramp resistance and rolling resistance)and the equivalent moment of inertia equivalent to the output end of the power system.Theoretical analysis of the advantages and disadvantages of the various load simulation methods used at this stage,through analysis and comparison,finally adopted the torque and speed closed-loop compound control method as the load simulation method in this paper,and theoretical derivation to verify the correctness of the method Sex.Provide theoretical support for the introduction of LADRC algorithm into the speed regulator in Chapter 4.thirdly,the various disturbances in the load simulation test system are analyzed in detail,and they are divided into model disturbances,torque disturbances and noise disturbances according to the different mechanisms of the disturbance sources.Since it is difficult to measure the disturbances such as non-linear disturbance and uncertainty in the test rig,the control method based on disturbance observer is a more effective method.Based on this point of view,the torque and speed closed-loop compound control method is improved,and LADRC control is introduced into the dynamometer model speed regulator.The simulation results show that the use of LADRC control reference and traditional PID control steering error and torque conversion can be significantly reduced in the presence of interference.It is proved that the improved method can further improve the accuracy of load simulation and is more robust to interference.Finally,a powertrain load simulation test bench was built,the electrical system of the test bench was introduced,and the main equipment of the test bench was selected.The Labview software is used to design the powertrain test control interface.Finally,a load simulation test is carried out using UDC operating conditions,and the test results show the effectiveness of the proposed method.