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How does Tesla car work?

          Tesla is an American multinational company that specializes in electric vehicles,energy storage and solar panel manufacturing.It is based in Palo Alto, California.Tesla made into the news with its amazing electric car the Model S which became the fastest electric car. The success of Tesla electric cars is due to the fact that the company also focused on the aesthetics of the car unlike other electric cars which were not so aesthetically pleasing!
          But have you ever wondered how Tesla car works? Well the prime mover of it is the induction motor invented by the great scientist Nikola Tesla. The other main components include a Battery Pack,Inverter and a Drive Train.
  
Tesla Model S (Source-Engadget.com)

          Let me explain how each and every component works. The soul of Tesla car induction motor consists of two main parts- Stator(stationary) and Rotor(Rotating). Stator is a 3 coil winding and a 3 phase power input is given to it. This 3 phase current produces a rotating magnetic field (RMF). Now if a rotor is placed in this RMF by Faraday's law an electric current is induced in the rotor due to which the rotor starts rotating. Since electricity is induced in the rotor it is called an induction motor. The speed of the RMF is known as the synchronous speed Ns.The rotor speed (N) is always less than the synchronous speed.N<Ns                               
            Image result for induction motor stator 
Stator and Rotor of an induction motor(Source-Learn Engineering) 

           In addition the induction motor is efficient for a wide range of speed (0-18000 rpm) thus it does not need a transmission. On the other hand an IC Engine is efficient only over a limited speed range ( 2000-4000 rpm) thus needs a gearbox.
           The induction motor recieves its power from a huge reservoir of battery pack. The battery pack consists of lithium ion cells which are connected in series and parallel combination to produce the power required to run the car. The lithium ion cells are placed in a module. There are over 16 modules and each module consists of around 400-450 cells. These modules combined make up the battery pack and this battery pack is placed on the floor of the car.
 
Battery pack in Tesla car(Source-Bloomberg)

           Now the battery supplies DC power which has to be converted to AC. This is done by an inverter. The question here arises that why is there a need to convert the DC power into AC? This is because it enables to control the speed of induction motor.This can be explained by getting back to the  working of induction motor. The synchronous speed of the rotating magnetic field (RMF) is directly proportional to the frequency of current supplied i.e Ns α f. Since the rotor constantly tries to chase the speed of the RMF we can say that N α f. If alternating current is supplied which has variable frequency the speed of the induction motor can be varied. Thus the inverter is used to vary the speed of the induction motor and thus that of the car.
             Finally there is the drivetrain. A drivetrain can be simply defined as the group of components that deliver power to the drive wheels. Here the power produced by the motor is transferred to the wheels via a single speed gearbox. In addition, achieving reverse gear is quite easy! This can be done just by reversing the power phase by a programmed controller and the motor rotates in opposite direction. The main function of transmission in Tesla is speed reduction and also to provide the necessary torque. An open differential is also a part of the transmission for traction control.
The Model S has a top speed of 155 mph (250 kmph) and it can accelerate from 0 to 60 miles per hour (0 to 97 km/hr) in 3.2 seconds.

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