3 Electric and Hybrid Vehicles requirement on the vehicles. Connectivity within the vehicle and with the infrastructure for both autonomous and shared vehicles is likely to be easier for implementation with EVs. The trend in using alternative vehicles is increasing today with EVs serving as ZEVs and hybrid vehicles filling in for ultra-low-emission vehicles. The core technologies for these alternative vehi- cles beyond the energy storage system are quite the same. The primary objective of this book is to introduce the system of alternative vehicle and the core enabling technologies embedded in that system.
Chapters have also been dedicated for introducing autonomous vehicle technologies and power system charging infrastructure in this book. 1.1 ELECTRIC VEHICLES An electric vehicle is a vehicle having the two features: (i) The energy source is portable and elec- trochemical or electromechanical in nature, and (ii) traction effort is supplied only by an electric motor. Figure 1.1 shows the block diagram of an EV system driven by a portable energy source. The electromechanical energy conversion linkage system between the vehicle energy source and the wheels is the powertrain of the vehicle. The powertrain has electrical as well as mechanical components.
More will be discussed on the components for EVs in a later section. The fuel for EVs is stored in an energy storage device, such as a battery-pack, for energy delivery upon demand. The primary source of energy for electricity generation for these vehicles is varied ranging from fossil fuels to solar energy. The BEV requires fuel delivered in electrical form to the vehicle through the electric power transmission system. Solar EVs use solar panels and a power con- verter to charge the batteries on the vehicle. The special feature of these EVs is that these are ZEVs as far as pollution within the vehicle is concerned.
The FCEV can also be ZEVs if pure hydrogen is used as fuel on board the vehicle. 1.2 HYBRID ELECTRIC VEHICLES The terms hybrid electric vehicle and hybrid vehicle generally refer to vehicles that use an IC engine in conjunction with one or more electric machines for propulsion. A hybrid road vehicle is one in which the propulsion energy during specified operational missions is available from two or more kinds or types of energy stores, sources or converters, of which at least one store or converter must be on board. The definition of hybrid road vehicle is proposed by the technical committee 69 of Electric Road Vehicles of the International Electrotechnical Commission.
The definition of hybrid vehicles can be extended to vehicles that have engines different from IC engines. The vehicle in which energy from fuel cells and battery-packs is utilized to deliver propulsion power through an electric motor is also a hybrid vehicle. The fuel cell is essentially an engine where stored chemical energy in the fuel is converted into electrical energy directly without the involvement of any combustion process. Triple hybrids are also possible where a fuel cell engine, electric machine and IC engine are all used to provide propulsion power.
The traction electric motors can operate independently or in association with the IC engine to power the wheels of the vehicle depending on the type of vehicle architecture. The blending of the power from two or Charger Drive Control Signals Powertrain Energy Storage (Battery) Power Converter Electric Motor Transmission, Driveshaft Wheels FIGURE 1.1 An EV system.