Experimental Study On NEDC Driving Cycle Of Vehicle Transmission In Test Bench

A large number of bench tests are needed in the design and development of transmission.The traditional indoor bench test is based on steady state and quasi dynamic test.However,with the development of automobile industry,the test of automatic transmission hardware in loop,transmission NVH test and other tests put forward higher requirements of bench simulation technology.The dynamic test technology of transmission is the key problem to be solved in the domestic and international automobile testing companies and research and development departments with the target of NEDC.In this paper,the simulation test of NEDC working condition is taken as the goal,the requirement of the simulation test of NEDC working condition is analyzed,the suitable load simulation algorithm is used to simulate the road resistance,the control logic of starting and shifting in platform are been designed to achieve the start and shift simulation,the feasibility of the road load simulation algorithm and the control strategy of starting and shifting platform are verified by using the method of simulation and actual test.At last,the target of the NEDC simulation of the transmission system is realized.First of all,the time course of "time-speed" of NEDC working condition is analyzed.According to the vehicle speed,acceleration(deceleration)time and gear position,the control logic is established,the cycle time,maximum speed,average speed and other indexes of NEDC were calculated.The mathematical model of the platform system is established according to the system structure of the NEDC test bench and the mathematical model of AC induction motor based on direct torque control is established.These theories provide a theoretical basis for simulation experiments.Then,the vehicle dynamics model is established by using the vehicle dynamics theory under the NEDC operating conditions.The advantages and disadvantages of the road load simulation algorithm based on the inverse model and the forward model are compared and analyzed.The speed tracking algorithm based on forward model is selected to simulate the road load.The driver,gearbox,engine,vehicle longitudinal dynamics model and bench system model are built in the enviroment of Matlab/Simulink software.The simulation experiments are carried out on urban and suburban conditions,the feasibility of load simulation control algorithm is verified by simulation analysis.Finally,in order to realize the NEDC simulation test in the transmission test bench,the computer software of the NEDC system is compiled by using C#.Using TwinCAT softwareto realize the configuration of the hardware system.The reasonable starting and shifting process control strategy is made by analyzing the difference between vehicle and test bench.The road load simulation algorithm based on the forward model and the start and shift control strategy of the vehicle are carried out on the manual transmission test bench.The simulation test of the NEDC working condition in the transmission performance test stand is completed.The test results show that the system can track the vehicle speed within a certain error range,and realize the target of the NEDC simulation.