Engine Starting Clutch Control Based On Single-Motor Hybrid System

Hybrid Electric Vehicle, HEV, is a kind of automotive between traditional fuel vehicle and electric vehicle, and has advantages of both kinds of vehicles. The HEV with CVT, which we research in this paper, uses multi-plate wet clutch to replace the torque converter that has low transmission efficiency and complex structure. With this,transmission system not only has high transmission efficiency, simple structure, low manufacturecost, convenient maintenance, but also retains the original continuously variable transmission characteristics of the CVT.As one of the difficulties of CVT key technologies, the performance of starting control is directly related to the overall performance of CVT transmission system. Engine starting is an important way to start a HEV, and is an essential way. For the engine starting of the HEV with CVT which using multi-plate wet clutch to replace torque converter, this paper focus on the following sections of research and analysis:First of all, briefly narrate the structure characteristics and working principle of the transmission system researched in this paper. Summarize the research status of the clutch starting control.Second, briefly narrate the structure and working principle of the clutch, and analyze the two starting devices of the transmission system. By analyze the transfer characteristic of the multi-plate wet clutch, establish the corresponding mathematical model. Analyze the evaluation indexes and influence factors of the multi-plate wet clutch and the starting control strategy and the process of engagement. Determine the clutch control strategy basis on the constant engine speed control strategy.Third, construct the steady-state output model of engine torque through the obtained engine test data. Do dynamic analysis for the engagement process of clutch and construct the kinetic model of transmission system. Determine the moment of resistance at the starting of the vehicle. According to the mechanism of the constant engine speed starting, formulate the control tables of the target engine speed, the target engine torque and hydraulic gradient and the time of the clutch transmission torque reaching to its target value.Fourth, briefly narrate the throttle piecewise linear control and fuzzy control often used in constant engine speed control strategy, and construct the corresponding model in MATALB/Simulink for simulation and analysis. For the problems exiting in both control methods, propose to use PID method to control throttle according the request torque of engine. Through the obtained results of constructing corresponding Simulink model, show that the performance of this method is better.At last, summarize the problems appearing in constant engine speed starting control strategy. Use BP Neural Network to estimate the target oil pedal opening and construct corresponding simulation model, and comparative analyze the results of before and after estimate. Propose to use fuzzy theory to establish driver’s starting intention model, and then correct the two control parameters of the target engine speed and the change rate of clutch hydraulic pressure in constant engine speed control. Through the obtained results of constructing simulation model, show that this method can well reflect driver’s starting intention and achieve constant engine speed starting under practical conditions.