New drive concepts need completely new platforms for electric cars to optimize range and driving performance. In recent years, for example, numerous newly developed platforms from global vehicle manufacturers have appeared for the coming generations of electric vehicles, from pre-series production to production readiness. We take a look at the special requirements for emission-free bodies.
While the placement of the engine and the drive axles were still in the foreground in conventional vehicles with combustion engines, completely different criteria have now come to the fore. In the case of battery-electric vehicles, this includes scalable installation of batteries in the underbody of the vehicle, a compact installation space for the electric motors and a spacious interior. In addition, criteria for suitability for everyday use come into focus. The trend is towards charging with faster 800-volt fast charging technology, which means that the charging stop at the fast charging station can be significantly reduced again. At a 350-kilowatt charging station, the battery can be charged in less than half the time with the help of the 800-volt technology under optimal conditions than with the 400-volt technology. Charging for a range of 100 kilometers according to WLTP is then possible in just under 5 minutes.
Flexibility in the charging systems
Flexible charging systems and bidirectional charging capabilities increase the chances of competitiveness in the hotly contested market for electromobility. A conversion of the charging voltage can shift the charging current to higher voltages regardless of the actual voltage and generate a faster charging capacity. The high-voltage battery can also be used as a power bank and then supply external electrical devices such as notebooks, PLEV or pedelecs with 230-volt alternating current while driving or when stationary. For this purpose, a household socket is often installed in the vehicle interior in the trunk. Other possible uses, such as breakdown assistance for electric vehicles, can also be implemented.
The placement of the battery with the lowest possible center of gravity between the axles and an optimal weight distribution in a ratio of 50 to 50 between the front and rear axles can be designed with an optimized platform structure. In everyday driving, the most important properties of a car include optimal cornering, rapid acceleration and high driving stability. The use of standardized battery cells and modules in the platform must be guaranteed in the long term. This reduces the working hours for a revision or the exchange of individual components in the event of a possible repair. This is associated with lower repair costs and fewer downtimes.
Leg freedom and safety features
The greatest advantage for passengers in battery-electric cars is the flat battery pack and thus the consistently flat floor in the interior. A relatively long wheelbase and flat floor can allow more leg room. With the freedom of movement gained, comfort increases, especially on long journeys. The front and rear seats can also be moved more flexibly and offer more design options for dividing up the vehicle interior. With a clever design, for example, as with the Volvo XC40, a generously level transport space can be created with the rear bench seat folded down.
A flexible and modular platform forms the basis for different vehicle segments. For the manufacturer, this means that modular adaptation for various vehicle classes is possible in the long term. Elementary areas for the battery housing, the wheel suspensions and absorbing elements against accidents are integrated into the structure. This means that elementary protective functions for passengers and the battery are an integral part of the concept.
The design options are also expanded under the bonnet. Replacing the internal combustion engine with starter, cooling system and exhaust gas treatment for the much more compact electric motor enables a smaller engine compartment. This leaves room for a flatter bonnet for a better view in the direction of travel. The conventional air conditioning and heating system is also more compact. Here clear progress can be seen through the use of flat displays instead of the traditional cockpit with the round instruments. This means that significantly more space can be designed for the driver and front passenger. This gain in space is noticeable through flexibly arranged storage and filing compartments.
At the European ones NCAP-Crash tests focus on the particularly common frontal and side impacts. The platforms have the primary task of absorbing and dissipating the impact energy. In this case, skeletal structures are often integrated in the front part of the frame to absorb energy. The drive battery must be protected particularly in the event of a side impact. The impact energy should be transmitted to the frame as far as possible. For this purpose, the batteries in the platforms in the floor area are usually encased in a frame made of high-strength steel.
The completely new architecture for purely electric cars with more compact installation space for the engine, the flat vehicle floor without a center tunnel and significantly more design freedom in the interior result in much more flexible application possibilities for future vehicle generations. Developments in the direction of a mobile lounge with autonomous driving systems can already be seen in the design studies.
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