基于单电机混合动力系统的发动机离合器起步控制
发布时间：2018-07-25 15:23
【摘要】：混合动力汽车是一种介于传统燃料汽车与纯电动汽车之间的汽车,兼具两者的优点。本文研究的CVT混合动力采用多片湿式离合器取代了传动效率较低、结构较复杂的液力变矩器,使得传动系统不但具有传动效率高、结构简单、制造成本低、维护保养方便等优点,还同时保留了原来CVT的无级变速特性。起步控制作为CVT关键技术中的难点之一,其性能的优劣直接关系到CVT传动系统的整体性能。发动机起步是混合动力汽车重要的起步方式,是必不可少的一种方式。本文对采用多片湿式离合器的CVT混合动力汽车的发动机起步主要开展如下几部分的分析与研究:(1)简述本文研究的CVT混合动力汽车传动系统的结构特点与工作原理;总结了离合器起步控制国内外研究现状。(2)简述了离合器的结构、工作原理以及对传动系统的两种起步装置进行了分析;通过分析多片湿式离合器扭矩的传递特性,建立了相应的数学计算模型;分析了多片湿式离合器起步的客观评价指标和影响因素、起步控制策略以及接合过程,确定了以发动机恒转速控制策略为基础的离合器控制策略。(3)通过得到的发动机试验数据构建了发动机扭矩稳态输出模型,对离合器接合过程进行了动力学分析并构建了传动系统的动力学模型,确定了起步时车辆的阻力矩;根据发动机恒转速起步控制机理,分析制定了发动机目标转速、目标发动机扭矩、离合器油压变化率、离合器传递扭矩达到目标值所需时间等主要控制数表。(4)简述了发动机恒转速控制策略中常采用的节气门分段线性控制和模糊控制方法,并在Matlab/Simulink中构建相应的模型进行仿真分析;针对这两种控制方法存在的问题,提出根据发动机需求扭矩,采用PID方法对节气门进行控制,通过建立相应Simulink模型得到的结果,表明此方法的控制性能更佳。(5)总结了发动机恒转速起步控制策略中出现的问题;采用BP神经网络对目标油门踏板开度进行预估,建立相应的仿真模型,并对比分析了预估前后仿真结果;提出利用模糊理论建立驾驶员的起步意图模型,并以此对发动机恒转速控制中发动机目标转速和离合器液压缸油压变化率两个控制参数进行修正,通过建立的仿真模型得到的仿真结果,表明此方法可以很好的体现驾驶员的起步意图同时实现实际条件下的发动机恒转速起步。
[Abstract]:Hybrid electric vehicle (HEV) is a kind of vehicle between traditional fuel vehicle and pure electric vehicle, which has the advantages of both. The CVT hybrid power system studied in this paper uses multi-disc wet clutch to replace the hydraulic torque converter with low transmission efficiency and complicated structure, which makes the transmission system have not only high transmission efficiency, simple structure, but also low manufacturing cost. Convenient maintenance and other advantages, but also retain the original CVT stepless speed characteristics. Starting control is one of the key technologies in CVT. Its performance is directly related to the overall performance of CVT transmission system. Engine starting is an important way of starting hybrid electric vehicle, is an indispensable way. In this paper, the engine start of CVT hybrid electric vehicle with multi-disc wet clutch is analyzed and studied as follows: (1) the structural characteristics and working principle of the CVT hybrid electric vehicle drive system studied in this paper are briefly described. The research status of clutch starting control at home and abroad is summarized. (2) the structure and working principle of clutch and two starting devices of transmission system are analyzed, and the transmission characteristics of torque of multi-disc wet clutch are analyzed. The corresponding mathematical calculation model is established, and the objective evaluation index and influencing factors of multi-disc wet clutch starting, starting control strategy and joint process are analyzed. The clutch control strategy based on engine constant speed control strategy is determined. (3) the steady output model of engine torque is constructed through the obtained engine test data. The dynamic analysis of clutch engagement process and the construction of dynamic model of transmission system are carried out, and the resistance moment of vehicle is determined when starting, and the engine target speed is analyzed according to the starting control mechanism of engine constant speed. The main control tables such as target engine torque, clutch oil pressure change rate, and the time required for clutch transmission torque to reach the target value are presented. (4) the throttle piecewise linear control and fuzzy control methods commonly used in engine constant speed control strategy are briefly described. According to the problems existing in these two control methods, the throttle is controlled by PID method according to the torque of engine demand, and the results obtained by establishing the corresponding Simulink model are obtained. It shows that the control performance of this method is better. (5) the problems in engine starting control strategy of constant speed are summarized, and the target throttle pedal opening degree is estimated by BP neural network, and the corresponding simulation model is established. The simulation results before and after the prediction are compared and analyzed, and the fuzzy theory is used to establish the starting intention model of the driver. The two control parameters of engine target speed and clutch hydraulic cylinder pressure change rate in constant engine speed control are modified, and the simulation results are obtained by the established simulation model. It shows that this method can well reflect the driver's starting intention and realize the engine constant speed starting under the actual conditions.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U469.7
[Abstract]:Hybrid electric vehicle (HEV) is a kind of vehicle between traditional fuel vehicle and pure electric vehicle, which has the advantages of both. The CVT hybrid power system studied in this paper uses multi-disc wet clutch to replace the hydraulic torque converter with low transmission efficiency and complicated structure, which makes the transmission system have not only high transmission efficiency, simple structure, but also low manufacturing cost. Convenient maintenance and other advantages, but also retain the original CVT stepless speed characteristics. Starting control is one of the key technologies in CVT. Its performance is directly related to the overall performance of CVT transmission system. Engine starting is an important way of starting hybrid electric vehicle, is an indispensable way. In this paper, the engine start of CVT hybrid electric vehicle with multi-disc wet clutch is analyzed and studied as follows: (1) the structural characteristics and working principle of the CVT hybrid electric vehicle drive system studied in this paper are briefly described. The research status of clutch starting control at home and abroad is summarized. (2) the structure and working principle of clutch and two starting devices of transmission system are analyzed, and the transmission characteristics of torque of multi-disc wet clutch are analyzed. The corresponding mathematical calculation model is established, and the objective evaluation index and influencing factors of multi-disc wet clutch starting, starting control strategy and joint process are analyzed. The clutch control strategy based on engine constant speed control strategy is determined. (3) the steady output model of engine torque is constructed through the obtained engine test data. The dynamic analysis of clutch engagement process and the construction of dynamic model of transmission system are carried out, and the resistance moment of vehicle is determined when starting, and the engine target speed is analyzed according to the starting control mechanism of engine constant speed. The main control tables such as target engine torque, clutch oil pressure change rate, and the time required for clutch transmission torque to reach the target value are presented. (4) the throttle piecewise linear control and fuzzy control methods commonly used in engine constant speed control strategy are briefly described. According to the problems existing in these two control methods, the throttle is controlled by PID method according to the torque of engine demand, and the results obtained by establishing the corresponding Simulink model are obtained. It shows that the control performance of this method is better. (5) the problems in engine starting control strategy of constant speed are summarized, and the target throttle pedal opening degree is estimated by BP neural network, and the corresponding simulation model is established. The simulation results before and after the prediction are compared and analyzed, and the fuzzy theory is used to establish the starting intention model of the driver. The two control parameters of engine target speed and clutch hydraulic cylinder pressure change rate in constant engine speed control are modified, and the simulation results are obtained by the established simulation model. It shows that this method can well reflect the driver's starting intention and realize the engine constant speed starting under the actual conditions.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U469.7
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