附录A.英文文献Conventional vehicles with IC engines provide good performance and long operating range by utilizing the high-energy-density advantages of petroleum fuels. However, conventional IC engine vehicles have the disadvantages of poor fuel economy and environmental pollution. The main reasons for their poor fuel economy are (1) mismatch of engine fuel efficiency characteristics with the real operation requirement (refer to Figures 2.34 and 2.35); (2) dissipation of vehicle kinetic energy during braking, especially while operating in urban areas; and (3) low efficiency of hydraulic transmission in current automobiles in stop-and-go driving patterns (refer to Figure 2.21). Battery-powered EVs, on the other hand, possess some advantages over conventional IC engine vehicles, such as high-energy efficiency and zero environmental pollution. However, the performance, especially the operation range per battery charge, is far less competitive than IC engine vehicles, due to the much lower energy density of the batteries than that of gasoline. HEVs, which use two power sources(a primary power source and a secondary power source), have the advantages of both IC engine vehicles and EVs and overcome their disadvantages.1,2 In this chapter, the basic concept and operation principles of HEV power trains are discussed.5.1 Concept of Hybrid Electric Drive TrainsBasically, any vehicle power train is required to (1) develop sufficient power to meet the demands of vehicle performance, (2) carry sufficient energy onboard to support the vehicle driving a sufficient range, (3) demonstrate high efficiency, and (4) emit few environmental pollutants. Broadly, a vehicle may have more than one power train. Here, the power train is defined as the combination of the energy source and the energy converter or power source, such as the gasoline (or diesel)heat engine system, the hydrogenfuel cellelectric motor system, the chemical batteryelectric motor system, and so on. A vehicle that has two or more power trains is called a hybrid vehicle. A hybrid vehicle with an electrical power train is called an HEV. The drive train of a vehicle is defined as the aggregation of all the power trains. A hybrid vehicle drive train usually consists of no more than two power trains. More than two power trains will make the drive train very complicated. For the purpose of recapturing braking energy that is dissipated in the form of heat in conventional IC engine vehicles, a hybrid drive train usually has a power train that allows energy to flow bidirectionally. The other one is either bidirectional or unidirectional. Figure 5.1 shows the concept of a hybrid drive train and the possible different power flow routes. A hybrid drive train can supply its power to the load by a selective power train. There are many available patterns of operating two power trains to meet the load requirement:1. Power train 1 alone delivers its power to the load.2. Power train 2 alone delivers its power to the load.3. Both power train 1 and power train 2 deliver their power to the load simultaneously.4. Power train 2 obtains power from the load (regenerative braking).5. Power train 2 obtains power from power train 1.6. Power train 2 obtains power from power train 1 and the load simultaneously.7. Power train 1 delivers power to the load and to power train 2 simultaneously.8. Power train 1 delivers its power to power train 2, and power train 2 delivers its power to the load.9. Power train 1 delivers its power to the load, and the load delivers the power to power train 2.In the case of hybridization with a gasoline (diesel)IC engine (power train 1) and a batteryelectric machine (power train 2), pattern (1) is the engine alone propelling mode. This may be used when the batteries are almost completely depleted and the engine has no remaining power to charge the batteries, or when the batteries have been fully charged and the engine is able to supply sufficient power to meet the power demands of the vehicle. Pattern (2) is the pure electric propelling mode, in which the engine is shut off. This pattern may be used for situations where the engine cannot operate effectively, such as very low speed, or in areas where emissions are strictly prohibited. Pattern (3) is the hybrid traction mode and may be used when large power is needed, such as during sharp accelerating or steep hill climbing. Pattern (4) is the regenerative braking mode, by which the kinetic or potential energy of the vehicle is recovered through the electric motor functioning as a generator. The recovered energy is then stored in the batteries and reused later on. Pattern (5) is the mode in which the engine charges the batteries while the vehicle is at a standstill, coasting, or descending a slight grade, in which no power goes into or comes from the load. Pattern (6) is the mode in which both regenerating braking and the IC engine charge the batteries simultaneously. Pattern (7) is t