How does an Electric Car work ? | Tesla Model S

Electric cars are making big waves
in the automobile world.

These noise-free, pollution-free
and high-performance vehicles

are expected to make their IC engine
counterparts obsolete by 2025.

This video will unveil the hidden
technologies behind the Tesla model S,

which recently became the world's
fastest accelerating car.

We will see how electric cars have
achieved superior performance

by analyzing the technology
behind the induction motor,

inverter,

lithium-ion battery power source,

and, above all, the synchronized
vehicle mechanism,

in a logical step-by-step manner.

The powerhouse of the Tesla
car is an invention

made by the great scientist Nikola Tesla
around 100 years back:

the induction motor.

The induction motor has two main parts:

the stator and the rotor.

You can see the construction
details of the motor here.

The rotor is simply a collection of conducting
bars short-circuited by end rings.

A three-phase AC power input
is given to the stator.

The three-phase alternating current in
the coils produces a rotating magnetic field.

The Tesla motor produces
a four-pole magnetic field.

This rotating magnetic field that induces
current on the rotor bars to make it turn.

In an induction motor,
the rotor always lags behind the RMF.

An induction motor has neither
brushes nor a permanent magnet.

At the same time it is robust and powerful.

The beauty of an induction motor is that

its speed depends on
the frequency of the AC power supply.

So just by varying the frequency
of the power supply,

we will be able to alter
the drive wheel speed.

This simple fact makes electric car
speed control easy and reliable.

The motor supply is from
a variable frequency drive,

which in turn controls motor speed.

The motor speed can range
from 0 to 18,000 rpm.

This is the most sizable
advantage electric cars have

when compared to internal combustion cars.

An internal combustion engine
produces usable torque

and power output only
within limited speed range.

Therefore,

directly connecting the engine rotation
to the drive wheel is not a clever idea.

A transmission must be introduced
to vary the drive wheel speed.

On the other hand, an induction motor
will work efficiently in any speed range.

Thus, no speed varying transmission
is needed for an electric car.

Moreover, an IC engine does not
produce direct rotational motion.

The linear motion of the piston has
to be converted to rotational motion.

This causes major problems
for mechanical balancing.

Not only is the internal combustion engine
not self-started like an induction motor.

Further, the power output of
an IC engine is always uneven.

Many accessories are needed
to solve these issues.

On the other hand, you will
have direct rotational motion

and uniform power output
with an induction motor.

Many components in the IC engine
can be avoided here.

As a result of these factors,

a great response rate and
higher power to weight ratio

comes naturally to an induction motor
resulting in superior vehicle performance.

But from where does
the motor receive power?

It's from a battery pack.

The battery produces DC power.

So before supply get to a motor
it has to be converted to AC.

An inverter is used for this purpose.

This power electronic device also
controls the AC power frequency,

thus controlling the motor speed.

Moreover, the inverter can even
vary the amplitude of the AC power

which in turn will control
the motor power output.

Thus, the inverter acts as
the brain of the electric car.

Now, let's turn our focus
to the battery pack.

You will be amazed to find

that they are just a collection
of common lithium-ion cells

similar to those used in your daily life.

The cells are connected in a combination
of series and parallel

to produce the power required
to run your electric car.

Glycol coolant is passed
through metallic inner tubes

through the gap between the cells.

This is one principal innovation of Tesla.

By using many small cells
instead of a few big cells

effective cooling is guaranteed.

This minimizes thermal hot spots and
even temperature distribution is achieved

leading to higher battery pack life.

The cells are arranged
as detachable modules.

There are 16 such modules in the battery
pack constituting around 7,000 cells.

The heated Glycol is cooled down
by passing through a radiator,

which is fitted at
the front of the vehicle.

Moreover, you can see how
such a low height battery pack,

when fitted close to the ground level,
will lower the vehicle center of gravity.

The lower of gravity improves
the stability of the car considerably.

The large battery pack is
also spread across the floor

offering structural rigidity
against side collisions.

Now let's get back to Tesla's drive-train.

The power produced by the motor is
transferred to the drive wheels via a gearbox.

As previously discussed, Tesla Model S
uses a simple single speed transmission

because the motor is efficient in
a wide range of operating conditions.

You can see that output speed from
the motor is reduced in two steps.

Even achieving the reverse gear
is quite easy in an electric car.

Just change the order of
the power phase for this.

The only purpose of electric
car transmission

is speed reduction and
associated torque multiplication.

The second component in
the gearbox is a differential.

The reduced speed drive is passed to it.

You can see this is
a simple open differential.

However, open differentials,
have a problem of traction control.

But, why does such an advanced
car use an open differential

rather than a limited slip differential?

The answer is that the open differential
is more rugged and can carry more torque.

The traction control problem that
occurs in an open differential

can effectively be overcome
with help of two methods:

selective braking

and cutting the power supply.

In an internal combustion engine,

this power supply cut by cutting
the fuel is not so responsive.

In an induction motor, however,
the power supply cut is quite responsive

and an effective means for
obtaining traction control.

In the Tesla,

this can all be accomplished using
a state-of-the-art algorithm

with help from Sensors and controllers.

In short, Tesla Motors has replaced
a complex mechanical hardware system

with smart responsive software.

Did you know an electric car
could be driven efficiently

with the help of just one pedal?

This is due to its powerful
regenerative braking system.

That means saving the huge
kinetic energy of the car

in the form of electricity
without wasting it as heat.

In an electric car, as soon as
you release the accelerator pedal,

the regenerative braking
comes into action.

The interesting thing is that,
during the regenerative braking

the same induction motor
acts as a generator.

Here the wheels drive the rotor
of the induction motor.

We know in an induction motor
the rotor speed is less than the RMF speed.

To convert the motor to a generator,

you just have to make sure that the rotor
speed is greater than the RMF speed.

The inverter plays a crucial role here
in adjusting the input power frequency

and keeping the RMF speed
below the rotor speed.

This will generate electricity
in the stator coils,

which is way higher than
the supplied electricity.

The generated electricity
can then be stored

in the battery pack after the conversion.

An opposing electromagnetic force acts
on the rotor during this process,

so the drive wheels and
the car will slow down.

This way vehicle speed can
be accurately controlled

during the drive using a single pedal.

The brake pedal can be applied
for a complete stop.

As you might already be aware,

electric cars are much safer
than internal combustion cars.

The cost of maintaining and
driving an electric car

is much lower than that
of an IC engine car.

With the drawbacks of the electric car evaded

through the advent of improved technology,

electric cars promise to
be the cars of the future.

We thank Mr. Jehu Garcia,

an electric car expert and YouTuber
for his technical support for this video.

Your support at patreon.com
is highly appreciated.

It enables us to make additional
free educational videos for you.

Thank you.