外文翻译(4.20)

（本文截取的是一篇国外学生的毕业论文中的一段论文名字是“A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles”）

The automotive industry is facing unprecedented challenges due to energy and environmental issues. The emission regulation is becoming strict and the price of oil is increasing. Thus, the automotive industry requires high-efficiency powertrains for automobiles to reduce fuel consumption and emissions. Among high-efficiency powertrain vehicles, Hy-brid Electric Vehicles (HEVs) are under development and in production as one potential solution to these problems. Thus, one of the most critical objectives of the HEV development is improving fuel economy. There are many ways of maximizing the fuel econo-my of a vehicle such as brake power regeneration，efficient engine operation，parasitic loss minimization，reduction of vehicle aerodynamic drag, and engine idle stop. Figure 1 compares the balance of the energy of a conventional vehicle with a hybrid electric vehicle。As can be seen in Figure 1, the hybrid vehicle saves fuel by utilizing engine idle stop, brake power regeneration, and efficient engine operation. Figure 1 also shows that the fuel consumed by the accessories, which include Vehicle Cooling System (VCS), Climate Control System (CCS), and electric accessories, is not negligible compared with the fuel consumed by the vehicle propulsion system. In addition, the portion of the energy consumption of the accessories in HEVs is bigger than that of conventional vehicles. This observation suggests that the efficient accessory system, particularly the VCS and CCS, is more important in high-efficiency vehicles because they have more effect on the fuel economy. The effect of the auxiliary load on the fuel economy of high-efficiency vehicles studied by Farrington et al [2]. They examined the effect of auxiliary load on vehicle fuel economy via a focus on climate control system. Figure 2 compares the impact of auxiliary load, i.e. the power consumed by accessory systems, on the fuel economy of the conventional and high fuel economy vehicle. As shown in the figure, a high fuel economy vehicle is much more affected by the auxiliary load than a conventional vehicle. Therefore, more efficient thermal management systems including VCS and CCS are essential for

HEV.

Figure 1. Energy flow for various vehicle configurations. (A) ICE, the conventional internal combustion, spark ignition engine; (B) HICE, a hybrid vehicle that includes an electric motor and parallel drive train which eliminates idling loss and captures some energy of braking [1].]

Figure 2. Comparison of fuel economy impacts of auxiliary loads between a conventional vehicle and a high fuel economy vehicle [2]

Achieving efficient VCS and CCS for HEVs requires meeting particular design challenges of the VCS and CCS. The design of the VCS and CCS for HEVs is different from those for conventional vehicles. VCS design for HEVs is much more complicated than that of conventional vehicles because the powertrain of HEVs has additional powertrain components. Furthermore, the additional powertrain components are operated at different temperatures and they are operated independently of the engine operation. The design of CCS for HEVs is also different from that of conventional vehicles because the temperature of the battery pack in HEVs is controlled by the CCS. Thus, the heat load for the C CS of HEVs is much higher than that for the CCS of conventional vehicles. Thus, this is another challenge for the design of the VTMS for HEVs.

As noted above, these additional powertrain components such as a generator, drive motors, a large battery pack, and a power bus require proper thermal management to prevent thermal run away of the power electronics used for the

electric powertrain components. Thus, the thermal management of the power electronics and electric machines is one of the challenges for the HEV development and various studies have been conducted [3-7]. Generally, dedicated VCS for the hybrid components are required as a result of the considerable heat rejections and different cooling requirements of the electric components. In the cooling system of HEVs, a cooling pump driven by an electric motor, rather than a pump driven by the engine, is used for the cooling circuit of the electric powertrain components because they need cooling even when the engine is turned off. The benefits of a controllable electric pump over the mechanical pump were studied by Cho et al. [8] in the case of the cooling system for a medium duty diesel engine. They used numerical simulations to assess the fuel economy and cooling performance and it is found that the usage of an electric pump in place of the mechanical pump can reduce power consumption by the pump and permit downsizing of the radiator. In addition to those benefits, the use of an electric pump makes the configuration of the cooing circuits in hybrid vehicles relatively flexible in terms of grouping components in different circuits. However, this flexibility raises an issue in optimizing cooling circuit architecture because of the complexity of the system and the parasitic power consumption of the cooling system. The performance and power consumption of the cooling system are also very sensitive to the powertrain operation. The powertrain operation is determined by the power management strategy, which changes in response to driving conditions of HEVs. Therefore, the effects of driving conditions must be considered during the design process of the cooling system. Thus, in light of these additional components, design flexibility, and the effects by vehicle driving condition, it is clear that the design of the VCS for HEVs demands a strategic approach compared with the design of the VCS for conventional vehicles.

Another challenge in designing the VTMS for HEVs is managing the cabin heat load generated as a result of the placement of the battery pack in the passenger compartment. In HEVs, the battery pack is located on board because of its lower

operating temperature compared with powertrain components. Therefore, battery thermal management system is a part of the Climate Control System (CCS) because the battery is cooled by using the CCS. Thus, the load on the CCS of HEVs is higher than that of conventional vehicles because the battery is the major heat source in the cabin. In addition, battery thermal management is important for the health and life of the battery. Although high temperature operation is better for the battery performance due to reduced battery loss and reduced battery thermal management power, high temperature operation is limited due to the battery durability and safety. Figure 3 shows the temperatu re dependency of the cycle life of Liion battery. As can be seen in the figure, the battery life drops dramatically when the battery is operated at higher than 60°C. The same happens at lower temperature. In extreme cases, lithium ion battery can explode by a chain reaction. Generally, the battery operating temperature is limited lower than 60°C for the lithium ion and lead acid battery [9-10]. Accordingly, battery thermal management associated with climate control system is a critical part of vehicle thermal management system design of HEVs. Therefore, a comprehensive vehicle thermal management system analysis including VCS and CCS is needed for the HEV vehicle thermal management system design.

Figure 3. Temperature dependency of the life cycle of Li-ion battery [11].

Recognizing the need for the efficient vehicle thermal management system (VTMS) design for HEVs, many researchers have tried to deal with the VTMS design for HEVs from various view-points. Because of the complexity and the necessity for the design flexibility of the thermal management system of HEVs, numerical modeling can be an efficient way to assess various design concepts and architectures of the system during the early stage of system development compared with experiments relying on expensive prototype vehicles. Traci et al.

[12] demonstrated that a numerical approach could be successfully used for thermal management system design of HEVs. They simulated a cooling system of an all-electric combat vehicle that uses a diesel engine as a prime power source and stores the power in a central energy storage system. They conducted parametric studies on the effect of the ambient temperature on the fan power consumption and the effect of the coolant temperature on the system size. Park and Jaura [13] used a commercial software package to analyze the under-hood thermal behavior of an HEV cooling system and studied the effect of the additional hardware on the performance of cooling system. They also

investigated the effect of an electronic module cooler on the conventional cooling system. These previous studies, however, focused on parametric studies and did not deal with the architecture design of the vehicle thermal management system considering the power consumption of the system.

There also have been many efforts to analyze the impact of the CCS on the HEV. Bennion and Thornton [6] compared the thermal management of advanced powertrains using an integrated thermal management system model and studied on the peak heat load over a transient vehicle driving cycle to minimize the size of cooling system. They also studied the cases involving efforts to minimize the cooling circuit by integrating low temperature circuits with high temperature circuits or A/C circuits. Kim and Pesaran [14] studied battery thermal management of HEV focused on the battery temperature distribution in the battery pack. Pesaran [15-16] studied the battery thermal models and the various methods of battery cooling in HEVs. However, these previous studies did not deal with the battery thermal management integrated with the A/C system, which is a part of the vehicle thermal management system.

As introduced above, although HEVs need more efficient VTMS than conventional vehicles, these previous studies do not present design guidelines to improve the efficiency and performance of the VTMS for HEVs. Thus, this st udy is focused on the design of the efficient VTMS for HEVs. The objective of this study is to develop guidelines and methodologies for the architecture design of the VTMS for HEVs, which are used to improve the performance of the VTMS and the fuel economy of the vehicle. To achieve the goal, a numerical modeling and simulation is adapted to develop the guidelines and methodologies. For the numerical simulations, a comprehensive model of the VTMS for HEVs which can predict the thermal response of the VTMS during transient operations is developed. A vehicle powertrain model for HEVs is also developed to simulate the operating conditions of the powertrain components because the VTMS components interact with the powertrain components. The developed model is

used for the system analyses and the design explorations of the VTMS for HEVs. Thus, this thesis is organized as follows. Chapter 2 describes the modeling approach for the vehicle powertrain system. Chapter 3 and 4 explain the VCS modeling approach and the CCS modeling approach respectively. Chapter 5 presents the results of integrated simulations. The vehicle powertrain system and VTMS including VCS and CCS are integrated to simulate the thermal response of the VTMS when the vehicle is driven over a specified driving schedule. The design guidelines which improve the efficiency and performance of the VTMS for HEVs are developed from the observations of the simulation results. In Chapter 6, the guidelines developed in Chapter 5 are applied to the architecture design of the VTMS for HEVs. Three VTMS architecture options designed based on the guidelines are compared based on the performance of the VTMS and the fuel economy of the vehicle. Chapter 7 summarizes this study and presents the conclusions made in the numerical study on the architecture design of VTMS for HEVs.

由于能源和环境问题，汽车行业正面临着前所未有的挑战。日益严格的排放法规和石油价格的不断增加。因此，汽车行业需要高效率的动力系统，以减少汽车油耗和排放。在高效率的动力系统的车辆里，HY -布里德电动汽车（HEV）正在开发和生产，作为这些问题的一个潜在解决方案。因此，HEV 的发展最重要的目标之一是提高燃油经济性。有许多方法能够最大限度地提高燃油经济，比如车辆制动功率再生，发动机的高效运行，摩擦损耗最小化，减少车辆的空气阻力，和发动机怠速停止。图1比较了混合动力电动汽车的传统车辆的能量平衡。在图1中可以看到，混合动力汽车可以节省燃料，利用发动机怠速停止，制动功率再生，高效的发动机操作。图1还显示，汽车配件其中包括汽车冷却系统（VCS），气候控制系统（CCS ），电器配件，消耗的燃料与车辆推进系统所消耗的燃料相比，是不可忽略的。此外，在混合动力汽车的配件部分能源消耗比传统汽车更大。这一结果表明，有效的辅助系统，特别是VCS与CCS，是高效率的车辆更重要的，因为他们有更多

的燃油经济性的影响。辅助负载的高效率车辆的燃油经济性的影响来自富华等人的研究[2]。他们通过对气候控制系统为重点的辅助负载，研究出其对车辆的燃油经济性的影响。图2比较了辅助负载的影响，即由附件系统消耗的功率，对传统和高燃油经济性车辆的燃油经济性。正如图中所示，燃油经济性高的车辆更比传统的车辆辅助负载的影响。因此，更高效的热管理系统，包括VCS与CCS对HEV来说是必不可少的。

图1，各种车辆配置的能量流。（一）ICE，传统的内燃机，火花点火发动机; （二）HICE ，混合动力汽车，其中包括一个电动马达和并联驱动列车，从而消除了空载损耗和制动捕捉一些能源[1]

图 2 ,比较传统车辆和高燃油经济性车辆之间辅助负载的燃油经济性的影响[2]

实现高效的VCS和CCS的混合动力车，VCS和CCS的设计将是一个巨大的挑战。VCS与CCS的混合动力汽车的设计是有别于传统汽车。VCS的混合动力汽车的设计是比传统汽车复杂得多，因为有更多的混合动力电动汽车动力总成的零部件。此外，额外的动力总成部件运行在不同温度下，它们是独立运作的发动机运转。因为在混合动力汽车电池的温度控制在于CCS ，CCS混合动力汽车的设计也有别于传统汽车。因此，混合动力车在CCS的热负荷是比传统汽车的CCS高得多。因此，这是另一混合动力车VTMS设计的挑战。

如上所述，这些额外的动力总成部件，如发电机，驱动电机，一个大型的电池组，电源总线需要适当的热管理，以防止热运行的电动动力总成零部件所使用的电力电子过热。因此，热管理，电力电子和电机的混合动力汽车的发展和各种研究已进行的挑战之一。一般来说，混合组件专用的VCS都需要相当大的热量拒绝和不同的冷却要求的电热元件。在混合动力汽车，由一个电动马达，而不是由发动机驱动泵驱动冷却泵，冷却系统，用于电动动力总成零部件的冷却回路，因为它们需要降温，甚至当发动机关闭时。Cho等进行

了研究可控电泵在机械泵的好处。[8]为中型柴油发动机冷却系统的情况下。他们利用数值模拟评估的燃油经济性和散热性能，它被发现使用的机械泵，电动泵由泵可以减少功耗，并允许散热器裁员。除了这些好处, 电泵的使用，使在不同的电路配置在混合动力汽车的咕咕相对灵活的电路分组组件. 然而，这种灵活性提出了一个问题，因为系统的复杂性和冷却系统的寄生功耗优化冷却电路架构。冷却系统的性能和功耗也非常敏感的动力总成业务。动力总成的操作取决于电源管理策略，在于驾驶混合动力车条件的改变。因此，驾驶条件的影响，必须考虑在冷却系统的设计过程。因此，在这些额外的组件，设计的灵活性，车辆行驶条件的影响，它是明确混合动力汽车VCS的设计要求的战略方针，与传统汽车设计的VCS区别。

在混合动力车的设计VTMS面临的另一个挑战是管理舱内的热负荷导致作为一个安置在乘客舱的电池。在混合动力汽车，电池组位于船上，因为与动力总成零部件相比其工作温度较低。因此，电池热管理系统是一个气候控制系统（CCS）的一部分，因为电池使用CCS冷却。因此，混合动力汽车在CCS 上的负载是高于传统汽车，因为电池是在机舱内的主要热源。此外，电池热管理对电池的健康和寿命是非常重要的。虽然高温作业对电池的性能更好，这是因为能够减少电池的损耗和降低电池热管理权力，由于电池的耐用性和安全性，高温作业是有限的。图3显示了锂离子电池的循环寿命的温度依赖性。图中可以看出，当电池在高于60°C操作时电池的寿命急剧下降，同样在较低温度下的情况也会这样。在极端情况下，锂离子电池可能发生爆炸的连锁反应。一般来说，电池的工作温度低于60℃的锂离子电池和铅酸电池有限[9-10]。因此，电池热管理与气候控制系统是混合动力汽车的热管理系统设计的一个重要组成部分。因此，需要一个全面的汽车热管理系统的分析，包括VCS与CCS的混合动力汽车热管理系统的设计。

图3 ，锂电池生命周期的温度依赖性[11]。

认识到需要高效车辆热管理系统（VTMS）的混合动力汽车的设计，许多研究人员一直试图从各种观点处理VTMS设计的混合动力车。由于混合动力电动汽车的热管理系统的复杂性和设计灵活性，在系统开发的早期阶段，与依靠昂贵的原型实验车辆相比，数值模拟可以成为一个有效的方式来评估不同的设计理念和系统架构。崔西等人[12]表明，数值方法，可以成功地用于混合动力电动汽车的热管理系统设计。他们模拟了全电战斗车辆采用柴油发动机作为一个主要的动力源和电源存储在一个中央能源存储系统的冷却系统。环境温度对风扇的电源消耗和冷却液温度对系统的规模效应的影响，他们进行了参数研究。Park和Jaura [ 13 ]采用商业软件包分析的发动机罩下的混合动力汽车冷却系统的热行为和对冷却系统的性能研究额外的硬件的效果。他们还研究了传统的冷却系统，电子模块散热器的效果。然而，这些以往的研究，重点参数研究，并没有处理车辆的热管理系统而只是考虑了系统功耗的架构设计。

也有很多努力，分析了CCS对HEV的影响。尼恩和桑顿[ 6 ]比较热管理和使用先进的动力系统的综合热管理系统模型研究了一个短暂的机动车驾驶周

期的峰值热负荷，以尽量减少冷却系统的大小。他们还研究了案件的努力，以尽量减少低温与高温电路或的A / C电路电路集成冷却回路。金正日和，Pesaran [ 14]研究电池的HEV集中在电池组的电池温度分布的热管理。pesaran [ 15-16 ]研究了电池的热模型和混合动力电动汽车电池冷却的各种方法。然而，这些研究没有处理电池热管理与集成的A / C系统，这是车辆热管理系统的一部分。

正如上面介绍的，虽然混合动力电动汽车需要比传统汽车更高效的VTMS ，这些以往的研究做不存在的设计指引，以提高效率和性能的混合动力汽车的VTMS 。因此，这项研究是专注于混合动力汽车的效率VTMS的设计。本研究的目的是发展混合动力车，这是用来改善VTMS和车辆的燃油经济性的表现VTMS建筑设计的指导方针和方法。为了实现这一目标，数值模拟和仿真，适应发展的指导方针和方法。对于数值模拟，在瞬变工作期间，可以预测的VTMS热反应的混合动力汽车的VTMS的综合模型。还开发一种混合动力电动汽车的汽车动力总成模型模拟动力总成零部件的经营状况，因为VTMS组件与动力总成部件交互。发达国家的模型用于混合动力汽车的VTMS系统的分析和设计探索。因此，本论文组织如下。第2章介绍了汽车动力总成系统的建模方法。第3和第4章分别解释VCS建模方法和CCS建模方法。第5章介绍了集成模拟的结果。汽车动力总成系统，包括VCS与CCS的VTMS 集成模拟了当车辆在一个指定的驾驶时间表驱动VTMS的热响应。设计指引，提高效率和性能的混合动力汽车的VTMS开发从仿真结果的意见。在第6章，第5章中制定的准则适用于建筑设计的混合动力汽车的VTMS 。三VTMS 的建筑设计基础上的指引进行比较的基础上的VTMS和车辆的燃油经济性的表现。第7章总结了本研究，并提出在建筑设计上的混合动力车VTMS的数值研究作出的结论