农用车离合器的设计【机械类毕业-含CAD图纸】
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译文题目： 农用车离合器设计 外文原文7Design Principle of Series (Electrical Coupling) Hybrid Electric Drive TrainThe concept of a series hybrid electric drive train was developed from the EV drive train.As mentioned in Chapter 4, EVs, compared with conventional gasoline- or diesel-fueled vehicles,have the advantages of zero mobile pollutant emissions, multienergy sources, and high efficiency. However, EVs using present technologies have some disadvantages: a limited drive range due to the shortage of energy storage in the on-board batteries, limited payload and volume capacity due to heavy and bulky batteries, and long battery charging time. The initial objective of developing a series HEV was aimed at extending the drive range by adding an engine/alternator system to charge the batteries on-board.A typical series hybrid electric drive train configuration is shown in Figure 7.1. The vehicle is propelled by a traction motor. The traction motor is powered by a battery pack and/or an engine/generator unit. The powers of both power sources are merged together in a power electronics-based and controllable electrical coupling device. Many operation modes are available to choose, according to the power demands of the driver and the operation status of the drive train system.Vehicle performance (in terms of acceleration, gradeability, and maximum speed) is completely determined by the size and characteristics of the traction motor drive. Motor power capability and transmission design are the same as in the EV design discussed in Chapter 4. However, the drive train control is essentially different from the pure electric drive train due to the involvement of the additional engine/generator unit. This chapter will focus on the design principles of the engine/alternator system, the drive train control, and the energy and power capacity of the battery pack. In this chapter,the term “peak power source” will replace “battery pack” because, in HEVs,the major function of the batteries is to supply peaking power and they can be replaced with other kinds of sources such as ultracapacitors, flywheels, or Combinations. 7.1 Operation PatternsIn series hybrid electric drive trains, the engine/generator system is mechanically decoupled from the driven wheels as shown in Figure 7.1. The speed and torque of the engine are independent of vehicle speed and traction torque demand, and can be controlled to any operating point on its speed-torque plane.Generally, the engine should be controlled in such a way that it always operates in its optimal operation region, where fuel consumption and emissions of the engine are minimized (see Figure 7.2). Due to the mechanical decoupling of the engine from the driven wheels, this optimal engine operation is realizable. However, it heavily depends on the operating modes and control strategy of the drive train.The drive train has several operating modes, which can be used selectively according to the driving conditions and wish of the driver. These operating modes are as follows:1. Hybrid traction mode: When a large amount of power is demanded,that is, the driver depresses the accelerator pedal deeply, both engine/generator and peaking power source (PPS) supply their powers to the electric motor drive. In this case, the engine should be controlled to operate in its optimal region for efficiency and emission reasons as shown in Figure 7.2. The PPS supplies the additional power to meet the traction power demand. This operation mode can be expressed asPdemand=Pe/g+Ppps,2. Peak power source-alone traction mode: In this operating mode, the peak power source alone supplies its power to meet the power demand,that is,Pdemand= Ppps. (7.2)3. Engine/generator-alone traction mode: In this operating mode, the engine/generator alone supplies its power to meet the power demand,that is,Pdemand= Pe/g. (7.3)4. PPS charging from the engine/generator: When the energy in the PPS decreases to a bottom line, the PPS must be charged. This can be done by regenerative braking or by the engine/generator. Usually,engine/generator charging is needed, since regenerative braking charging is insufficient. In this case, the engine/generator power is divided into two parts: one to propel the vehicle and the other to charge the PPS. That is,Pdemand= Pe/g+ Ppps. (7.4)It should be noticed that the operation mode is only effective when the power of the engine/generator is greater than the load powerdemand. It should be noted that PPS power is given a negative sign when it is being charged.5. Regenerative braking mode: When the vehicle is braking, the traction motor can be used as a generator, converting part of the kinetic energy of the vehicle mass into electric energy to charge the PPS.As shown in Figure 7.1, the vehicle controller commands the operation of each component according to the traction power (torque) command from the driver, the feedback from each of the components, and also the drive train and the preset control strategy. The control objectives are to (1) meet the power demand of the driver, (2) operate each component with optimal efficiency,(3) recapture braking energy as much as possible, and (4) maintain the state of charge (SOC) of the PPS in a preset window.7.2 Control StrategiesA control strategy is a control rule that is preset in the vehicle controller and commands the operation of each component. The vehicle controller receives operation commands from the driver and feedback from the drive train and all the components, and then makes decisions to use proper operation modes.Obviously, the performance of the drive train relies mainly on control quality,in which control strategy plays a crucial role.In practice, there are a number of control strategies that can be employed in a drive train for vehicles with different mission requirements. In this chapter,two typical control strategies are introduced: (1) maximum state-of-charge of peaking power source (Max. SOC-of-PPS) and (2) engine turn-on and turn-off(engine on/off) or thermostat control strategies.7.2.1 Max. SOC-of-PPS Control StrategyThe target of this control strategy is to meet the power demand commanded by the driver and, at the same time, maintain the SOC of the PPS at its high level. The engine/generator is the primary power source, and the PPS is the secondary source. This control strategy is considered to be the proper design for vehicles in which performance (speed, acceleration, gradeability, etc.) is the first concern, such as vehicles with frequent stopgo driving patterns and military vehicles in which carrying out their mission is the most important objective. A high SOC level in the PPS will guarantee the high performance of vehicles at any time.The Max. SOC-of-PPS control strategy is depicted in Figure 7.3, in which points A, B, C, and D represent the power demands that the driver commanded in either traction mode or braking mode. Point A represents the commanded traction power that is greater than the power that theengine/generator can produce. In this case,the PPS must produce its power to make up the power shortage of the engine/generator. Point B represents the commanded power that is less than the power that the engine/generator produces when operating in its optimal operation region (refer to Figure 7.2).In this case, two operating modes may be used, depending on the SOC level of the PPS. If the SOC of the PPS is below its top line, such as less than 70%, the engine/generator is operated with full load. (The operating point of the engine/generator with full load depends on the engine/generator design. For details, see the next section.) Part of its power goes to the traction motor to propel the vehicle and the other part goes to the PPS to increase the energy level. On the other hand, if the SOC of the PPS has reached its top line, the engine/generator traction mode alone is supplied,that is, the engine/generator is controlled to produce power equal to the demanded power, and the PPS is set at idle. Point C represents the commanded braking power that is greater than the braking power the motor can produce (maximum regenerative braking power).In this case, a hybrid braking mode is used, in which the electric motor produces its maximum braking power and the mechanical braking system produces the remaining braking power. Point D represents the commanded braking power that is less than the maximum braking power that the motor can produce. In this case, only regenerative braking is used. The control flowchart of the Max. SOC-of-PPS is illustrated in Figure 7.4.7.2.2 Engine OnOff or Thermostat Control StrategyThe Max. SOC-of-PPS control strategy emphasizes maintaining the SOC of the PPS at a high level. However, in some driving conditions, such as drivingfor a long time (with a low load) on a highway at constant speed, the PPS can be easily charged to its full level, and the engine/generator is forced to operate with power output smaller than its optimum. Hence, the efficiency of the drive train is reduced. In this case, the engine onoff or thermostat control strategy would be appropriate. This control strategy is illustrated in Figure 7.5. The operation of the engine/generator is completely controlled by the SOC of the PPS. When the SOC of the PPS reaches its preset top line, the engine/generator is turned off and the vehicle is propelled only by the PPS. On the other hand,when the SOC of the PPS reaches its bottom line, the engine/generator is turned on. The PPS gets its charging from the engine/generator. In this way,the engine can be always operated within its optimal deficiency region.7.3 Design Principles of a Series (Electrical Coupling)Hybrid Drive TrainSuccessful design of the drive train system means ensuring the vehicle being capable of achieving the desired performance, such as acceleration, grade-ability, high speed, and high operating efficiency. The traction motor drive,engine/generator unit, PPS, and electrical coupling device are the major design components of concern. Their design should primarily be considered at the system level so as to ensure that all the components work harmoniously.7.3.1 Electrical Coupling DeviceAs mentioned above, the electrical coupling device is the sole linkage point for combining the three sources of powers together: engine/generator, PPS, and traction motor. Its major function is to regulate the power (electric current)flow between these power sources and sinks. The power (current) regulation is carried out based on the proper control of the terminal voltages. The simplest structure is to connect the three terminals together directly as shown in Figure 7.6.This configuration is the simplest and has the lowest cost. Its major feature is that the bus voltage is equal to the rectified voltage of the generator and that of the PPS. The bus voltage is determined by the minimum of the two voltages above. The power flow is solely controlled by the voltage of the generator. To deliver its power to the traction motor and/or the PPS, the open circuit voltage(zero current) of the generator, rectified, must be higher than the PPS voltage.This can be done by controlling the engine throttle and/or the magnetic field of the generator. When the engine/generator is controlled to generate the rectified terminal voltage equal to the open circuit voltage of the PPS, the PPS does not deliver power and the engine/generator alone powers the electric motor. When the rectified voltage of the engine/generator is lower than the PPS voltage, the PPS alone powers the electric motor. In regenerative braking,the generated bus voltage by the traction motor must be higher than the PPS voltage. However, the voltage generated by the traction motor is usually proportional to the rotational speed of the motor. Therefore, the regenerative braking capability in low speed will be rather limited for this design. It is also obvious that this simple design requires the engine/generator and the PPS to have the same rated voltage. This constraint may result in a heavy PPS due to the high voltage.Adding a DC/DC converter, and thus releasing the voltage constraints,may significantly improve the performance of the drive train.Two alternative configurations are shown in Figures 7.7 and 7.8. In the configuration of Figure 7.7, the DC/DC converter is placed between the PPS and the DC bus and the enginegeneratorrectifier is connected directly to the DC bus.In this configuration, the PPS voltage is allowed to be different from the DC bus voltage, and the rectified voltage of the engine/generator is always equal to the DC bus voltage. In the configuration of Figure 7.8, the DC/DC converter is placed between the enginegeneratorrectifier and the DC bus and the PPS is directly connected to the DC bus. Contrary to the configuration of Figure 7.7, the DC/DC converter conditions the rectified voltage of the engine/generator and the voltage of the PPS is always equal to the DC bus voltage.Among these two configurations, the one in Figure 7.7 seems to be more appropriate. Its advantages over the other one are mainly the following: (1)changes in the voltage of PPS do not affect the DC bus voltage, (2) the energy in the PPS can be fully used, (3) the voltage of the DC bus can be maintained by controlling the engine throttle and/or the magnetic field of the generator, (4)a low PPS voltage can be used, which may lead to small and light PPS pack and less cost, and (5) the charging current of PPS can be regulated during regenerative braking and charging from the engine/generator.It is obvious that the DC/DC converter in this configuration has to be bidirectional. In the case of the rated voltage of the PPS being lower than the DC bus voltage, the DC/DC converter has to boost the PPS voltage to the level of the DC bus to deliver its power to the DC bus and buck the DC bus voltage to the level of the PPS charging voltage to charge the PPS. In regenerative braking, if the voltage generated by the traction motor at a given low speed is still higher than the voltage of the PPS, the buck DC/DC converter in the PPS charging direction is still usable. However, if the voltage generated by the traction motor at the given low speed is lower than the terminal voltage of the PPS, the DC/DC converter may need to boost the DC bus voltage to charge the battery. In this case, a buck/boost (step down/step up) converter is needed. The basic functions of the DC/DC required converter are summarized in Figure 7.9.中文译文系列的设计原理（电耦合）的混合动力传动系串联式混合动力电动传动系的概念是从EV开发传动系。正如在第4章，电动汽车，与传统的汽油或柴油为燃料的汽车相比，具有零移动污染物的排放，多能量源，效率高的优点。然而，使用本技术的电动车具有一些缺点：由于在车载电池，有限的有效载荷和体积容量能量储存器的短缺的有限驱动范围由于笨重的电池，和长的电池充电时间。开发一系列的HEV的初步目标是针对通过将发动机/交流发电机系统的车载电池充电延伸的驱动范围。一个典型的串联式混合动力传动系统的配置如图7.1所示。车辆由一个牵引电动机推动。牵引电机由电池组和/或发动机/发电机单元供电。两个电源的功率被合并在一起，基于电力电子的和可控的电耦合装置。许多操作模式来选择，根据驾驶和驱动系系统的操作状态的电力需求。车辆性能（在加速，爬坡能力，和最大速度方面）完全由大小和牵引电动机驱动器的特性来确定。马达功率能力和传输设计是相同的如在第4章中讨论的电动汽车的设计但是，传动系控制是从纯电动驱动系本质上的不同，由于附加的发动机/发电机单元的参与。本章将集中在发动机/交流发电机系统，该传动系控制，以及对电池组的能量和功率容量的设计原则。在这一章中，术语“峰值功率源”将代替“电池组”，是因为，在混合动力汽车中，电池的主要功能是提供峰值功率，它们可以被替换为其他种类的来源，如超级电容器，飞轮，或组合。7.1操作模式在串联式混合动力驱动系统中，发动机/发电机系统被机械地从从动轮解耦，如图7.1。所述的速度以及发动机的扭矩是独立的车速和牵引转矩的需求，并且可被控制以在它的速度转矩平面上的任何工作点。通常，发动机应该以这样一种方式，它总是在它的优化运行区域进行操作，其中，燃料消耗和发动机的排放最小化的控制（见图7.2）。由于从驱动轮的发动机的机械去耦，这最佳发动机操作是可实现的。然而，它在很大程度上取决于传动系的操作模式和控制策略。传动系具有多种操作模式，其中可以有选择地根据驱动条件和驾驶员的愿望被使用。这些操作模式如下：1. 混合牵引模式：当大量的功率被要求，也就是，驾驶员尽力踩下加速器踏板，发动机/发电机和峰值功率源（PPS）即提供其功率给电动马达驱动。在这种情况下，发动机应控制在提高效率和发射的原因及其最佳区域中操作，如图7.2。该PPS提供的额外功率，以满足所需牵引功率。这种操作模式可以表示为：Pdemand=Pe/g+Ppps。这里Pdemand是指驾驶员所需求的能量，Pe/g是指发动机/发电机所提供的能量，Ppps是指峰值功率源所提供的能量。2. 峰值功率源单独牵引模式：在此操作模式中，峰值功率源单独提供其功率，以满足电力需求，也就是Pdemand=Ppps3. 发动机/发电机单独牵引模式：在此操作模式中，发动机/发电机单独提供其功率，以满足电力需求，也就是Pdemand=Pe/g4. 从发动机/发电机的PPS充电：当在PPS的能量减小到底线，将PPS必须充电。这可以通过再生制动或发动机/发电机来实现。一般，发动机/发电机充电是必要的，因为再生制动充电不足。在这种情况下，发动机/发电机的功率被分成两个部分：一个用于推进车辆，而另一个以将PPS充电。也就是Pdemand=Pe/g+Ppps应当注意到，当发动机/发电机的功率大于负载所需的电源的操作模式是唯一有效的。应当指出的是，PPS功率被赋予负号时，它被充电。5. 再生制动模式：当车辆处于破碎，牵引电机可以用作发电机，将所述车辆质量的动能的一部分转换成电能，以将PPS充电。如图7.1，车辆控制器根据所述牵引动力（转矩）命令从驱动，从各成分的反馈，并且也驱动系和预置控制策略命令的每个组件的操作。控制目标是：（1）满足驾驶员的要求功率;（2）操作的每个组件具有最佳效率，（3）夺回制动能量尽可能，和（4）保持的充电量（SOC）的状态将PPS在预先设定的窗口。7.2控制策略控制策略是预置在车辆控制器和命令每个组件的操作的控制规则。车辆控制器接收从传动系驱动器和反馈和所有的部件操作命令，然后做出决定，以使用正确的操作模式。显然，传动系的性能主要依赖于控制质量，在这种控制策略中起着至关重要的作用。在实践中，有许多可在传动系被用于车辆具有不同的任务要求的控制策略。在这一章中，两个典型的控制策略进行了介绍：（1）（最大充电状态的PPS）最大状态的充电调峰电源和（2）发动机的导通和关断（发动机/关）或恒温器控制策略。7.2.1最大充电状态的PPS这种控制策略的目标是满足由驾驶员指令，并在同一时间的电力需求，维持将PPS的SOC在其高的水平。发动机/发电机是主电源，和PPS是辅助源。这种控制策略被认为是正确的设计，车辆在性能（速度，加速度，爬坡能力等）是第一个关注，如频繁的车辆走走停停的驾驶模式和军用车辆在执行他们的任务是最重要的目标。在PPS高充电水平将保证车辆在任何时间处于高性能状态。最大充电状态的PPS控制策略示于图7.3，其中点A，B，C和D表示，司机指令在任一牵引模式或制动模式的电力需求。点A表示所命令的牵引动力，其大于该发动机/发电机能够产生的功率。在这种情况下，PPS必须产生它的力量来弥补发动机/发电机的电力短缺。点B代表命令的功率小于在其最佳工作区域工作时，该发动机/发电机产生的功率（参见图7.2）。在这种情况下，两种工作模式可以被使用，这取决于PPS的SOC水平。如果PPS的SOC水平低于其顶线，诸如小于70，在发动机/发电机进行满载操作时。（发动机/发电机满负荷的工作点取决于发动机/发电机的设计，具体请参见下一节。）它的功率的一部分进到牵引马达来推进车辆，另一部分进入到PPS增加能量水平。另一方面，如果将PPS的SOC水平已经达到最大值，该发动机/发电机的牵引单独模式被提供时，即发动机/发电机受到控制，PPS设定在闲置，以产生功率等于所述需要的功率
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