By designing a slim-line battery pack positioned below the floor and combining the motor and power electronics into a compact module between the rear wheels, the Tesla engineering team developed a car that truly integrates Tesla’s proven powertrain. The innovative integration is the key to exploiting the advantages of an electric car and creates new opportunities in safety and performance while maximizing interior space.
The battery pack is a lightweight, high-performance structure in its own right, but when married to the state-of-the-art body structure, the result is a platform with unsurpassed integrity. The Tesla Vehicle Platform enables efficiency, safety, and design not possible in an architecture conceived around the combustion engine.
PREPARING FOR PRODUCTION
The expanded display, unveiled at the 2011 North American International Auto Show, represents Model S at the Alpha phase and publicly demonstrates Tesla’s vehicle engineering prowess.
Before Model S enters production, characteristics such as aerodynamics, stability and handling, crash safety, performance, and range,will have been thoroughly tested using both computer simulations and prototype vehicles. Tesla will complete two vehicle testing phases, Alpha and Beta.The Alpha phase began in 2010 and has already excelled as the meticulous computer simulations predicted.
Quality is a philosophy, and is designed-in from the outset. Computer simulations aided in developing a quality product with modular components and a built-in Quality Manufacturing process using an assembly line running at 20,000 units per year.
BEAUTY IN MOTION
The streamlined Model S is a product of unprecedented teamwork between aerodynamicists and designers. Every millimeter of the body has been evaluated using computer simulations and wind tunnel testing to produce second-to-none aerodynamic qualities.
The perfectly flat battery pack provides an ideal starting point for all-important under-car airflow and is supplemented by a flat front under-tray and rear diffuser. The result is aerodynamic perfection more commonly expected of the upper echelons of race cars. Gizmos such as vortex generators and spoilers employed by other vehicles to fix inefficient design are unnecessary on Model S.
Air flows smoothly around Model S, enhancing efficiency and range. Wind tunnel testing has demonstrated a best-in-class drag coefficient, as Tesla computer simulations predicted.
NOT JUST ALONG FOR THE RIDE
To realize the benefits of its electric powertrain, Tesla employed a holistic approach to vehicle architecture, tightly packaging components throughout the car. The battery pack exemplifies this approach: in addition to protecting the cells it contains, the pack performs many additional roles.
When combined with the body structure, the pack contributes to the overall torsional stiffness, providing an unparalleled stiffness-to-weight ratio amongst production vehicles. The pack integration augments the strength of the passenger cabin, endowing Model S with superior safety. The pack improves underbelly and wheel well aerodynamics and lowers the center of gravity for better handling.
The location of the battery pack below the floor also enables rapid interchangeability. The system is engineered to recharge in 45 minutes. Model S will be available with three range options: 255 km, 370 km, 480 km.
Tesla has poured its learning from the Roadster’s proven, road-tested technology into Model S. The powertrain comprises the battery pack, motor, single-speed gear box, drive inverter, and control software. The system benefits from innovative liquid temperature management.
The Tesla motor is nearly three times as efficient as a gasoline engine, and enables Model S to accelerate from 0 to 60 mph in less than six seconds.
The motor and power electronics are tightly integrated to mount within the rear sub-frame module. The packaging innovations result in more usable, cabin space and a center of gravity lower than is possible in combustion vehicles.
ELECTRIC GIVES YOU MORE
When the Tesla design team asked, “what do we put where the gasoline engine traditionally goes?” The answer was a second trunk. With the motor integrated into the rear axle, Model S provides about twice the storage space of other vehicles in its class. The rear trunk cavity is spacious enough to allow for rear-facing child seats. Gone are space-limiting compromises such as a gas tank, catalytic converter, tailpipe, and engine.
Model S will provide drivers premium ride quality combined with precision handling. The Tesla-designed advanced suspension systems were created to work in harmony with the rigid and light Tesla platform.
The double-wishbone, virtual-steer-axis front suspension and multi-link rear are both lightweight, aluminum intensive designs that optimize tire contact with the road. A gasoline engine forces a typical steering rack to hang below the car, which creates a feeling of numbness when steering. Not so with Model S: the programmable electric power steering, mounted in a rigid structure optimizes feedback from the road to the driver. The battery pack endows Model S with an exceptionally low center of gravity, enhancing stability and minimizing corner roll.
Both suspensions are modular assemblies. The rear module includes not only the sub-frame and suspension, but the motor, gearbox, power electronics, and drive shafts. The complete assembly, an example of Tesla’s aptitude for compact and efficient package design, can be installed on the assembly line as one module.
OBSESSED WITH EFFICIENCY, COMMITTED TO SAFETY
When engineering Model S, Tesla focused on three tenets to increase efficiency: enhanced aerodynamics, weight reduction, and decreased rolling resistance. Weight-saving benefits made aluminum a natural choice for the body and pack structure. Extrusions, stampings, and castings were combined to provide exceptional rigidity and strength.
Together, the body and pack structures work in harmony to efficiently benefit the whole. In the event of collision, the strong frame protects occupants as crumple zones soften and absorbs the energy of an impact. Without the obstructions a combustion engine presents, the front of Model S can be truly optimized for crash safety. Model S is engineered with the intent to achieve 2012 five-star NHTSA safety ratings.