WEBVTT

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Electric cars are making big waves in the automobile world

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These noise-free, pollution-fre and high-performance] vehicles are expected to make their IC engine counterparts obsolete by 2025

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This video will unveil the hidden technologies behind the Tesla model S which recently became the world's fastest accelerating car

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We will see how electric cars have achieved superior performance by analyzing the technology behind the induction motor,

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inverter

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Lithium-Ion battery Power source,

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and, above all, the synchronized vehicle mechanism, in a logical step-by-step Manner

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The powerhouse of the tesla car is an invention made by the great scientist Nikola Tesla around 100 Years back: the induction motor

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The induction Motor has two main parts: the stator and the rotor

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You can see the construction details of the motor here

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

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

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The three-phase alternating current in the coils produces a rotating magnetic field. The tesla motor produces a four-pole Magnetic field.

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

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

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An induction motor has neither brushes nor a permanent magnet. At the same time it is robust and powerful.

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The beauty of an induction motor is that its speed depends on the frequency of the AC power supply.

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So just by varying the frequency of the power supply, we will be able to alter the drive wheel speed

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This simple fact makes electric car speed control easy and reliable

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The motor Supply is from a variable frequency drive, which in turn controls motor speed.

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

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This is the most sizable advantage electric cars have when compared to internal combustion cars.

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An Internal Combustion engine produces usable torque and power output only within limited speed range

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

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A transmission must be introduced to vary the drive wheel speed

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

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Thus no speed varying transmission is needed for an electric car

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moreover an IC engine does not produce direct rotational motion

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

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This causes major problems for mechanical balancing

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

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further, the power output of an IC engine is always uneven

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Many accessories are needed to solve these issues

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On the other hand you will have direct rotational motion and uniform power output with an induction motor

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many components in the IC engine can be avoided here

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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

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vehicle Performance

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But from where does the motor receive power?

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From a battery pack

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the battery Produces DC power

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so before supply get to a motor it has to be converted to AC

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An inverter is used for this purpose

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This power electronic device also controls the Ac power frequency thus controlling the motor speed

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Moreover the Inverter can even vary the amplitude of the ac power which in turn will control the motor power output

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Thus the inverter acts as the brain of the electric car

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Now let's turn our focus to the battery pack

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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

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The cells are connected in a combination of series and parallel to produce the power required to run your electric car

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Glycol coolant is passed through metallic inner tubes through the gap between the cells

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This is one principal innovation of Tesla

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by using many small cells instead of a few big cells

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Effective cooling is guaranteed

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This minimizes thermal hot spots and even temperature distribution is achieved leading to higher battery pack life

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The cells are arranged as detachable modules

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

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The heated Glycol is cooled down by passing through a radiator, which is fitted at the front of the vehicle

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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

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The lower of gravity improves the stability of the car considerably

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The large battery pack is also spread across the floor offering structural rigidity against side collisions

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Now let's get back to Tesla's drivetrain

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

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As previously discussed, tesla model s uses a simple

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Single speed transmission because the motor is efficient in a wide range of operating conditions

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

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Even achieving the reverse gear is quite easy in an electric car. Just change the order of the power phase for this

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The only purpose of electric car transmission is speed reduction and associated torque multiplication

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The second component in the Gearbox is a differential

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The reduced speed drive is passed to it

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You can see this is a simple open differential. However, open differentials, have a problem of traction control

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But why does such an advanced car use an open differential rather than a limited slip differential?

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

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A problem that occurs in an open differential can effectively be overcome with help of two methods:
selective braking and

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cutting the power supply

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In an Internal combustion engine this power supply cut by cutting the fuel is not so responsive

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In an induction motor, however, the power supply cut is quite responsive and an effective means for obtaining traction control

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In the tesla this can all be accomplished using a state-of-the-art algorithm with help from Sensors and controllers

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

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responsive software

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Did you know an electric car could be driven efficiently with the help of just one pedal?

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This is due to its powerful regenerative braking system

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That means saving the huge kinetic energy of the car in the form of electricity without wasting it as heat

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In an electric car, as soon as you release the accelerator pedal the regenerative braking comes into action

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The interesting thing is that during the regenerative braking the same induction motor acts as a generator

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Here the wheels drive the rotor of the induction motor

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

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To convert the motor to a generator. You just have to make sure that the rotor speed is greater than the RMF speed

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The inverter plays a crucial role here in adjusting the input power frequency and keeping the RMF speed below the rotor speed

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This will generate electricity in the stator coils, which is way higher than the supplied electricity

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The generated electricity can then be stored in the battery pack after the conversion

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An opposing electromagnetic force acts on the rotor during this process, so the drive wheels and the car will slow down

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This way vehicle speed can be accurately controlled during the drive using a single pedal

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The brake Pedal can be applied for a complete stop

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As you might already be aware, electric cars are much safer than internal combustion cars

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The cost of maintaining and driving an electric car is much lower than that of an IC engine car

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With the drawbacks of the electric car evaded through the advent of improved technology, electric cars promise to be the cars of the future

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We think mr.. J. Who Garcia an electric car expert and youtuber for his technical support for this video?

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