Electric vehicles battery architecture

In general, there are two different architectures for BMSs namely, decentralized systems and centralized systems. These two architectures are illustrated for an electric vehicle (EV) application in Fig. 8.3 (decentralized) and Fig. 8.4 (centralized). In the decentralized system (Fig. 8.3), the individual BMS tasks are located in different devices. The charge control is part of the charger, the discharge control is part of the EV drive system, the battery state determination is carried out within a range meter, and so on. Some BMS tasks must be implemented in more than one device, especially in the case of safety management. Normally, there is little or no communication between the devices, so an optimized operation is not possible. Another disadvantage is that the battery-relevant control functions are located in different devices. Thus, each device must be adapted to the particular battery used. 

A typical EV architecture is shown in Fig. 11.27. This architecture is very similar to that for the hybrid battery packs, with the exception that there may be high voltage loads, such as climate control or heaters, that will power directly from the high voltage pack. Electric vehicles are also different from all other electric drives... 

Since the development of electric vehicles differs from that of conventional cars, due for instance to the different architectures of both vehicle types, a different and appropriate way of working is required. From a tools and methods point of view, it is important to define processes and identify the tools that are suitable to tackle that challenge. Especially the influence of the battery on car behavior and stmctuxe is to be analyzed and taken into account, since it is one of the key factors of a battery-driven electrical vehicle. This calls for... 

If the loading duration of the battery is considered, it is evident that a potential buyer would seriously ask himself what would happen the next morning, in the case he would have forget to charge the battery. This emphasizes the fact that many car makers do not seem to take seriously the fact that an electric vehicle requires new and innovative encompassing concepts rather than just introducing a battery into a car with a conventional architecture. 

The optimum energy management of the vehicle and its components is one of the primary challenges of fuel cell hybrid electric vehicles. The difficulties result from the high nonlinearity of the control path (fuel cell, power electronics, battery, and electric machine) and subsequently the complexity of the control architecture. 

Changes to the architecture of the vehicle electric power system are expected to proceed in an evolutionary rather than a revolutionary manner. It is the intention of the automotive industry and its suppliers that the 42-V PowerNet [9,11] will be available for technical situations which require very high power demands. Due to cost considerations as well as to uncertainties with respect to the availability and reliability of newly designed components [35], modifications will be introduced stepwise only when really needed. This process is expected to last many years. Therefore, the long-term solutions to the problems of increased vehicle electric power demand, the implications for battery design and manufacturing, and the possible intermediate steps have all to be considered carefully by the battery industry. 

Changes in vehicle electric system architecture have immediate consequences for the performance profile expected from the battery. More specialized battery designs will be needed. Multiple batteries will be combined to meet demands and battery state detection will help to keep the battery in its best operational window to assure a sufficient power supply for critical components in all vehicle operational conditions. 

---