3 Vehicle Architectures and Design The propulsion component that is common in advanced vehicle technologies alternative to the con- ventional internal combustion engine vehicles (ICEVs) is the electric powertrain. Electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid vehicles (PHEV) and fuel cell electric vehi- cles (FCEV) all have an electric powertrain component whether or not they have another engine- equipped mechanical powertrain component. The placement of the different powertrain components in the EVs and hybrid vehicles with respect to each other is referred to as the architecture of the vehicle.
The motivation for exploring and developing new configurations is higher carbon emission reduction and enhanced driver experience benefits. The configuration of a battery electric vehicle (BEV) has the simplest architecture with the pow- ertrain consisting of an electric machine, a power electronics converter and a gearbox. In HEVs, there is an additional powertrain, and at least two fuel sources feeding into their respective energy converters. Consequently, HEVs offer the possibility of various different types of powertrain archi- tectures. This chapter presents the architectures and design of these alternative vehicle technologies.
This chapter starts with the components used and their sizing in EVs. The classification of hybrid architectures and component sizing of HEVs are discussed. The features of PHEV and FCEV are also included in this chapter. Further details of fuel cells and fuel cell vehicles appear in Chapter 6. The fuels in alternative vehicles can be derived from sources alternative to the fossil fuels. Many of these vehicles also use a combination of alternative fuels and conventional fuels.
The EVs may appear to be operating solely on alternative fuels by the use of modern battery technology, but the ultimate source may be the conventional fossil fuels depending on how the electricity to recharge the batteries was generated. EVs with batteries charged from renewable energy sources, such as wind, solar and hydro, provide the best scenario of alternative energy transportation. 3.1 ELECTRIC VEHICLES EVs, as defined in Chapter 1, have portable energy source and the tractive effort comes solely from one or more electric machines. The BEV powered by only one or more electric machines has the most straightforward architecture without the need for power blending.
The detailed structure of an EV system along with the interaction among its various components is shown in Figure 3.1. The primary components of an EV system are the motor, controller, power source and transmission. Battery Charger Wheel Vehicle Controller Motor Controller Transmission Diff. Acceleration Braking Wheel FIGURE 3.1 Major electrical components and choices for an EV system. 51 User inputs User inputs Accel. pedal Brake pedal Battery Storage Power Electronic Inverter Electric Motor