Tesla Model S Powertrain Solution
Like many e-cars, the Tesla Model S has no need of numerous car components including a transmission, gears and a clutch. Therefore, this car has fewer elements prone to wear or failures requiring repair. But it also means that the Model S has a wide range of special features which you won’t find in standard cars. In this article, we will consider the powertrain solution implemented in the Model S.
The car is equipped with the asynchronous three-phase AC motor. This electric motor was developed by the company Tesla Motors and is unrivaled throughout the world. The electric motor is installed on the rear axle of the car. The engine capacity amounts to 416 h.p., while the max. torque reaches up to 600 Nm. The electric motor is cooled by means of liquid cooling system.
There is no
transmission (in the traditional sense) in the Model S, the motor is directly
attached to the axle. All Tesla cars are equipped with a single-step reduction
gear unit having a fixed ratio (approximately 9:1). Since the motor can spin
backwards (reverse) and has max. torque at 0 RPM with a max. RPM of 18000 no
transmission is required. Tesla engineers tried to apply a 2-speed gearbox in
the Roadster model, but this solution didn’t go well.
There are
two types of gearbox solutions for cars equipped with IC-engines – automatic
and manual gearboxes. Manual gearboxes require clutch control with the help of
the particular pedal. So, what does all this have to do with the Model S that
has neither gears nor a clutch? The answer is - driving experience.
Model S scheme
Driving a Tesla car feels like driving a car with a manual gearbox. The car will roll if you ease off on the brake pedal when the car runs downhill. Tesla implemented the “hill assist” function in the 5.9 software update, but that only holds the vehicle for a moment before the car starts rolling again. Release of the Model S gas pedal as the driver gets close to a traffic light will lower the car speed via regenerative braking which feels like downward gear change and engine braking, but without the noise. Moreover, Tesla engineers also introduced the «Creep» feature, which emulates the automatic gearbox operation. Thanks to this new feature the car will start moving when the brake pedal is released.
All in all, the reduction gear unit, installed in the Model S, is simple in design and has a high efficiency rate (98-99%). Thus, the electric car does not require ATF fluids, filters (oil and air filter), spark plugs, or timing belt. In other words, electric cars practically do not have components of the “risk group”. It is very convenient, since there is no need for frequent repair services and constant extra expenses.
