Study On The Dynamics And Control Paramants Optimization Of The CDE 1.6L Engine Cold Test System

Engine cold test technology is a kind of engine test technology which is a comprehensive analysis of the mechanical performance of automotive engine without dismantling.During the process of the engine cold test,engine does not ignite and work;So the cold test technology has the advantages of high controllability,low noise and vibration,low using cost and so on.However,in the cold test conditions,the engine crankshaft torque fluctuation exists.So in the cold test process,there are problems such as high fluctuation of the steady state speed of the crankshaft,the overshoot of the rotation speed and the slow dynamic response of the system and so on.So the engine cold test system has high requirements on the hardware structure and the control parameters of the driving system.In this thesis,based on the structure and optimization of control parameters o f CDE 1.6L engine cold test system as research object,through the AMESim platform,the following models were mainly studied:(1)The dynamic model of CDE 1.6L engine during the cold test process;(2)The model of driving system of cold test system.Through the joint simulation of these two models,the influence of the control parameters of cold driving system in the cold test process was analyzed,and according to the requirement of the dynamic performance and static performance of the system,the control parameters of the system were optimized.In the research of the model one,according to the source and characteristics o f the drag torque of the crankshaft in the engine cold test process,the Stribeck friction model and the gas dynamics model in the cylinder were established.Secondly,through the simulation results the model,the characteristics of pressure in engine cylinder change with the speed and the drag torque of the crankshaft with the speed were studied.In the process of cold test,the drag torque of the crankshaft is mainly caused b y the gas compression torque in cylinder.Through engine bench test,the characteristics of engine cylinder pressure at different speeds were measured.The experimental results are compared with the simulation results,the reliability of dynamic model of CDE 1.6L engine during the cold test process was determined.In the research of the model two,firstly,the mathematical model of permanent magnet brushless synchronous motor(PMSM)was established;The difference between direct torque control method and vector control method of PMSM was analyzed;Emphasis laid on the structure and work flow of the vector control system based on voltage method;And through the dynamic response a nd steady state response simulation experiment,the good dynamic response and steady state performance of the system were proved.Finally,the joint simulation of model one and model two was established,Using the orthogonal test,through the analysis of the dynamic performance,steady state performance and system stability of the system,the influence of speed loop PID parameters and the reasonable selection range of the system performance are determined;After that,the speed loop PID parameters optimizatio n functions of the cold driving system were written by the Design Exploration modular,and the optimization operation of the speed loop PID parameters based on genetic algorithm was realized.The dynamic performance,steady state performance and system stability of system were improved obviously.