62 Electric and Hybrid Vehicles Battery Charger Converter Motor Controller Motor Drive Control Signals Battery Motor and Inverter Wheels Mechanical Coupling High Voltage Bus FIGURE 3.10 EV equivalent powertrain architecture. FIGURE 3.11 Skateboard chassis layout for EVs. other EV manufacturers. A skateboard chassis layout for EVs is shown in Figure 3.11. The skate- board design provides greater vehicle design freedom, more usable passenger space and a modular platform to increase production scale. With an e-powertrain concept, it is possible to design heavier vehicles with more than e-axles.
3.5 POWERTRAIN COMPONENT SIZING The complete design of a vehicle is complex involving numerous variables, constraints, considerations and understanding of the systems interactions. The interactions are typically interdisciplinary and require multi-physics analysis and simulations. The full treatment of a vehicle design is beyond the scope of this book, but from the roadway fundamentals, the vehicle dynamics and the archi- tectures presented thus far, we can address the fundamental calculations involved in sizing of the powertrain components. The calculations provide the design data for starting computer modeling and simulation for detailed analysis of a complex EV and HEV systems.
The computer modeling and simulation continues with design iterations and subsystem resizing and controller updates until simulation results meet the specifications. The basic equations and principles that lay the founda- tion for the design of electric and hybrid vehicles are presented next. Design considerations will be highlighted when appropriate. The primary design specifications related to powertrain sizing are: (i) the initial acceleration, (ii) rated velocity on a given slope, (iii) maximum % grade and (iv) maximum steady-state velocity. The zero-emission range is the most important specification for sizing the capacity of the battery- pack.
The energy required for a given acceleration and constant steady-state velocity can be used for the sizing of the energy system.