考虑动力系功率损失和CVT响应滞后集成发动机-CVT控制的性能

本文考虑由于CVT速比变化引起动力系功率损失和惯性转矩推荐了一种集成发动机一无级变速器(CVT)控制算法。此外还提出了减少CVT速比响应滞后对驱动转矩影响的补偿算法。实验结果表明，最佳发动机速度补偿算法给出最佳发动机工作点在最佳工作线附近。当加速度响应接近相等时和最佳转矩补偿比较。建议把集成发动机-CVT控制算法的特点和传统CVT相比较，加速时采用集成控制来实现在最佳工作线上找到最佳发动机工作点。     

混合电动车辆复式电力机械无级变速器的控制策略

本文为双型电力机械无级变速器(EVT)混合电动车辆推荐了一个操纵策略,首先,进行网络分析估算复式EVT与速比有关的效率,由网络分析发现,当功率循坏发生在电驱动变速器时,EVT效率降低,而EVT在速比范围内工作时,可提供相对高的系统的效率,这就要求操纵策略应从动力系总效率观点出发而不只是内燃机的热效率.为了开发复式EVT的操纵策略,采用反向基础控制求出包括EVT的HEV动力系的动力学方程式,以及指定马达转矩控制算法.在HEV动力系动态模型的基础上,采用Cruise和MAT-LAB/Simulink开发了一个HEV模拟器.该模拟结果指出,本文推荐的操纵策略可以操纵发动机在预定速比范围内具有相对高的效率,它比常规控制方法提供的燃油经济性有所改进.这是基于变速器效率可以用于HEV复式EVT设计要求的操纵策略.     

采用金属推带无级变速器换档控制改进燃油经济性

推荐采用CVT换档速度控制的一种算法来改进金属推块无级变速器车辆的燃油经济性.重新调整CVT换档动力学方程式,可以找到CVT换档速度与工作油压以及初始油压有关,绘制换档速度图估算工作油压对换档速度的影响,以求出换档速度为目标,提出工作油压计算的一种算法.为了估算换档速度和液体的损耗,采用考虑CVT换档动力学的试验证实求得工作油压控制阀和比例控制阀的动力学模型.根据仿真的结果,尽管由于工作压力增加液体损失增加,发觉燃油经济改进为2%.     

基于CVT变速器的燃油经济性优化潜力研究

为了获得某CVT车型速比参数优化对燃油经济性直接改善的潜力,首先,获得了NEDC循环中的发动机运行工况分布特征,市区循环中绝大部分工况都处于最佳燃油经济性曲线以下。随后,根据速比控制方法评估了可以优化的区域,其中市区循环中7%的工况可以优化,市郊循环中部分工况(车速达到70 km/h和100 km/h时),由于速比限值限制无法优化调整。根据仿真结果,仅调整CVT变速器的速比参数,包括调整部分工况至最佳燃油经济性曲线上,或在全部区域内优化,或放宽CVT变速器的速比范围,最大节油潜力的直接贡献达到3. 12%。     

金属带式无级变速器速比控制的改进算法

针对常规PID算法在无级变速器(CVT)速比控制中产生积分饱和与对干扰敏感的问题,分析了CVT速比控制及其常规PID控制算法原理,在对遇限削弱积分与不完全微分两种算法分析的基础上,提出了CVT速比控制改进PID算法。采用改进PID算法和常规PID算法,分别进行了发动机节气门开度6%～55%的汽车起步加速、55%～80%急加速、80%～25%减速等工况的MatlabSimulink对比仿真试验。试验结果表明,改进PID算法有效的减少了CVT速比控制系统的超调量、缩短了滞后时间、提高了系统的控制性能。     

金属带式无级变速器速比变化对车辆加速度的影响规律研究

搭建了金属带式无级变速器传动系统的数学模型,并通过实例仿真分析了CVT速比变化特性对车辆加速度的影响。研究结果证明,CVT速比变化率能够在一定程度上影响车辆加速度,应当根据速比变化的方向适当地控制速比变化率。该项研究工作为CVT速比变化率的控制策略提供了理论上的依据和方法。     

基于模糊免疫PID的CVT速比控制研究

针对装备金属带式无级变速器的某款车型,确定了发动机的目标转速调节特性曲线和无级变速器的目标速比,建立了CVT液压控制执行机构的数学模型。考虑到CVT速比控制的时变非线性和时滞耦合性的特点,借鉴生物免疫系统中的免疫反馈原理,结合模糊控制和PID控制各自的优点,设计了模糊免疫PID速比控制器,并在Simulink环境下对CVT整车模型起步、急加速和上坡工况进行了仿真分析。结果表明,模糊免疫PID速比控制能够很好地跟踪目标速比,具有良好的动态响应性能和较高的稳态控制精度。     

复合式汽车变速器最佳动力性匹配研究

以复合式汽车变速器为研究对象,对该变速器的最佳动力性速比优化匹配方法进行了研究。建立了动力传动系统的数值模型,以驱动功率为动力性目标,建立了无极变速传动装置最佳动力性速比优化目标函数模型。基于simulation X软件,建立了装有复合式变速器的汽车仿真模型,按照最佳动力性的原则对CVT的速比进行了优化,并对比分析了速比优化前后汽车的动力性和燃油经济性。仿真结果表明提出的复合式汽车变速器最佳动力性速比优化匹配算法具有良好的有效性。     

复合式汽车变速器最佳经济性速比优化算法研究

复合式汽车变速器,由金属带式无级变速器(continuously variable transmission,CVT)和有级变速传动装置组成,可根据汽车工况的需要分别实现无级变速传动和有级变速传动。综合考虑了发动机效率和CVT效率对汽车油耗的影响,提出了一种复合式汽车变速器最佳经济性速比优化方法。首先建立了动力传动系统的数值模型,为系统优化匹配和仿真分析奠定了基础。其次,建立了CVT最佳经济性速比匹配优化目标函数模型。基于simulation X软件,建立了装有复合式变速器的汽车仿真模型,对CVT的最佳经济性速比进行了优化,并对比分析了速比优化前后汽车的动力性和燃油经济性,证明了本文算法的有效性和实用性。     

基于改进PID的CVT速比控制器设计

针对常规PID速比控制器在无级变速器(CVT)速比控制过程中存在的稳定性差、反应慢等问题,对其积分项和微分项分别采用抗积分饱和及不完全微分进行改进,设计了改进PID速比控制器。设计了CVT速比控制仿真模型,仿真模型中速比控制器子模型分别采用常规PID速比控制器和改进PID速比控制器,在Simulink环境下进行了阶跃速比跟踪对比仿真试验。试验结果表明,改进PID速比控制器与常规PID速比控制器相比能够使CVT速比控制过程的超调量减小、反应速度加快、振荡次数减少,CVT实际速比对目标速比跟踪良好,系统的稳态特性和动态特性得到改善。     

CVT ratio control for improvement of fuel economy by considering powertrain response lag

A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.     

Integrated engine-CVT control considering powertrain response lag in acceleration

In this paper, an engine-CVT integrated control algorithm is suggested by considering the inertia torque and the CVT ratio change response lag in acceleration. In order to compensate for drive torque time delay due to CVT response lag, two algorithms are presented: (1) an optimal engine torque compensation algorithm, and (2) an optimal engine speed compensation algorithm. Simulation results show that the optimal engine speed compensation algorithm gives better engine operation around the optimal operation point compared to the optimal torque compensation while showing nearly the same acceleration response. The performance of the proposed engine-CVT integrated control algorithms are compared with those of conventional CVT control, and It is found that optimal engine operation can be achieved by using integrated control during acceleration, and improved fuel economy can be expected while also satisfying the driver’s demands.     

A study on regenerative braking for a parallel hybrid electric vehicle

In this paper, a regenerative braking algorithm is presented and performance of a hybrid electric vehicle (HEV) is investigated. The regenerative braking algorithm calculates the available regenerative braking torque by considering the motor characteristics, the battery SOC and the CVT speed ratio. When the regenerative braking and the friction braking are applied simultaneously, the friction braking torque corresponding to the regenerative braking should be reduced by decreasing the hydraulic pressure at the front wheel. To implement the regenerative braking algorithm, a hydraulic braking module is designed. In addition, the HEV powertrain models including the internal combustion engine, electric motor, battery, CVT and the regenerative braking system are obtained using AMESim, and the regenerative braking performance is investigated by the simulation. Simulation results show that the proposed regenerative braking algorithm contributes to increasing the battery SOC which results in the improved fuel economy. To verify the regenerative braking algorithm, an experimental study is performed. It is found from the experimental results that the regenerative braking hydraulic module developed in this study generates the desired front wheel hydraulic pressure specified by the regenerative braking control algorithm.     

Optimal engine operation by shift speed control of a CVT

In this paper, an algorithm to increase the shift speed is suggested by increasing the line pressure for a metal belt CVT. In order to control the shift speed, an algorithm to calculate the target shift speed is presented from the modified CVT shift dynamics. In applying the shift speed control algorithm, a criterion is proposed to prevent the excessive hydraulic loss due to the increased line pressure. Simulations are performed based on the dynamic models of the hydraulic control valves, powertrain and the vehicle. It is found from the simulation results that performance of the engine operation can be improved by the faster shift speed, which results in the improved fuel economy by 2% compared with that of the conventional electronic control CVT in spite of the increased hydraulic loss due to the increased line pressure.     

Evaluation of fuel economy for a parallel hybrid electric vehicle

In this work, the fuel economy of a parallel hybrid electric vehicle is investigated. A vehicle control algorithm which yields operating points where operational cost of HEV is minimal is suggested. The operational cost of HEV is decided considering both the cost of fossil fuel consumed by an engine and the cost of electricity consumed by an electric motor. A procedure for obtaining the operating points of minimal fuel consumption is introduced. Simulations are carried out for 3 variations of HEV and the results are compared to the fuel economy of a conventional vehicle in order to investigate the effect of hybridization. Simulation results show that HEV with the vehicle control algorithm suggested in this work has a fuel economy 45% better than the conventional vehicle if braking energy is recuperated fully by regeneration and idling of the engine is eliminated. The vehicle modification is also investigated to obtain the target fuel economy set in PNGV program.     

轻度混合动力电动汽车多能源动力总成控制器的开发

以某轻度混合动力电动汽车为对象研究整车功率分配策略,详细分析驾驶员功率需求确定、发动机工作区域优化和制动能量回收控制策略,并在此基础上开发了多能源动力总成控制器的硬软件系统。通过对多能源动力总成控制器的硬件在环仿真试验和实车匹配测试,不仅证明该控制器能高效、可靠地运行,而且取得了降低整车油耗16．9％,排放指标远低于欧III标准的控制效果。     

基于遗传算法的商用车传动系的参数优化

研究了综合考虑动力性和燃油经济性指标的汽车动力传动系数学模型。以燃油经济性最佳为优化目标以及整车动力性作为约束条件,根据指定柴油机和整车参数,运用遗传算法对某商用货车的传动系参数进行优化计算。结果显示,优化后的传动系参数,使得整车在原地起步加速时间基本不变的情况下最高车速提高了2.98%,使得整车混合百公里油耗降低了0.67%。表明优化参数使整车的动力性和燃油经济性得到了不同程度的改善。     

汽车无级变速器原理与控制

随着节能和环保要求的日益提高,能够连续改变传动比,进而改善汽车动力性、经济性和排放指标的无级变速器成为汽车变速器的主要发展方向。在简单说明采用无级变速器的原因之后,对当前汽车无级变速器的主要形式———金属带式无级变速器的工作原理和发展过程进行了详细介绍;并对当前基于无级变速器的汽车动力传动系的主要控制方法做了简单分析,分别阐述了在不同工况下的控制方法以及先进控制理论在基于无级变速器的控制中的应用。     

新型功率分流式混合动力传动系统工作模式分析与参数设计

提出一种基于金属带式无级变速传动(Continuously variable transmission, CVT)与行星齿轮机构的新型功率分流式混合动力汽车动力传动系统方案,分析该系统所具有的各种工作模式,并针对长安某车型参数完成了动力系统和传动系的参数匹配设计.在MatLab/Simulink环境下建立基于该系统的整车性能仿真模型,进行整车动力性能及UDDS/10～15循环工况下的燃油经济性仿真计算分析,结果表明所提出的新型混合动力传动系统百公里加速时间仅为9.65 s,UDDS和10～15循环工况下的等效百公里油耗分别为4.32、3.74 L.