IntroductionConventional Breaking SystemRegenerative Breaking & Its WorkingKinetic Energy Recovery System(K.E.R.S)Discharge mode of K. E. R. SBenefits of Regenerative Breaking SystemLimitations of Regenerative Breaking SystemConclusionReference

What are brakes?A brake is a device that decelerates a

moving object / prevents an object

from accelerating.

Brakes use friction to convert kinetic

energy into heat

Guiding principle- kinetic energy

increases quadratic ally with velocity

-K = mv2 / 2

When the brake is pushed the caliper

containing piston pushes the pad

towards the brake disc which slows

the wheel down.

Convectional braking system Conventional braking

systems use friction to

counteract the forward

momentum of a moving

car.

As the brake pads rub

against the wheels,

excessive heat energy is

created.

This heat energy

dissipates into the air,

wasting up to 30% of the

car's generated power

Regenerative braking

Regenerative braking technology funnels the energy created by the

braking process back into the system in the form of charging the

battery for further use

In a regenerative braking system the energy normally lost in the

braking process is transferred to the generator from the rotating

axel and then transferred to the battery, thus saving energy

How does it work

The system that drives the vehicle does the majority of the braking. When the driver steps

on the brake pedal of an electric or hybrid vehicle, these types of brakes put the vehicle's

electric motor into reverse mode, causing it to run backwards, thus slowing the car's

wheels. While running backwards, the motor also acts as an electric generator, producing

electricity that's then fed into the vehicle's batteries.

Vehicles driven by electric

motors use the motor as a

generator when using

regenerative braking: it is

operated as a generator

during braking and its output

is supplied to an electrical

load; the transfer of energy to

the load provides the braking

effect.

Many modern hybrid and

electric vehicles use this

technique to extend the range

of the battery pack.

v v

Motor

IC Engine

Generator Battery

Wheel

WheelMotor

Transmission

IC Engine

Generator Battery

Wheel

Wheel

Motor

Transmission

IC Engine

Generator Battery

Wheel

Wheel

Scenario 1: Low speed - Power is provided by electric motor using energy supplied by the DC battery

Scenario 2: Braking – Kinetic energy is converted to electric energy during regenerative braking by electric motor and supplied to battery.

Scenario 3: High speed – Power is provided by IC engine and electric motor via generator. Generator also charge battery during high speed.

Over view

Kinetic energy recovery system

The device recovers the

kinetic energy that is

present in the waste heat

created by the car’s braking

process.

The concept of transferring

the vehicle’s kinetic energy

using Flywheel energy

storage was postulated by

physicist Richard Feynman

in the 1950s

How does K. E.R. S work

When the driver brakes most of the kinetic energy is still converted to

heat energy but a portion is treated differently and is stored up in the

car.

When the driver presses his boost button that stored energy is

converted back into kinetic energy

The mechanical KERS system utilises flywheel technology to recover

and store a moving vehicle’s kinetic energy which is otherwise wasted

when the vehicle is decelerated.

Flywheel of K. E . R. S

Made of steel and carbon fibre

which rotates at over 60,000 RPM.

60 kW power transmission in

either storage or recovery

400 kJ of usable storage

Discharge mode of K. E. R. S

During this stage when the driver pushes the boost button the

flywheel acts as a propulsion motor and discharges the energy to the

wheels

The Flywheel rotor is decelerated during boost discharge mode and

the energy is converted back.

Flywheel acts as a generator and sending energy back to electric

motor, which works as propulsion motor.

Benefits of regenerative braking

Reduction of pollutionIncrease in engine lifeBreaking is not total lossWear Reduction

Reduction in pollutionRailway vehicle – The Delhi Metro saved around 90,000 tons of carbon

dioxide (CO2) from being released into the atmosphere by regenerating

112,500 megawatt hours of electricity through the use of regenerative

braking systems

Regenerative brakes have been able to improve the performance of engines.

This has been exhibited in the Motor sport industry –The system used by F! cars

is called K. E. R. S (Kinetic Energy Recovery System)

Increase engine efficiency

Breaking is not total lossConventional brakes apply friction to convert a vehicle’s kinetic energy into heat. In energy terms, therefore, braking is a total loss: once heat is generated, it is very difficult to reuse. The regenerative braking system, however, slows a vehicle down in a different way.

Wear ReductionAn electric drive train also allows for regenerative breaking which increases Efficiency and reduces wear on the vehicle brakes.

Limitations of regenerative braking system The regenerative braking effect drops off at lower speeds, therefore the

friction brake is still required in order to bring the vehicle to a complete

halt.

The friction brake is a necessary back-up in the event of failure of the

regenerative brake.

Most road vehicles with regenerative braking only have power on some

wheels (as in a 2WD car) and regenerative braking power only applies to

such wheels, so in order to provide controlled braking under difficult

conditions (such as in wet roads) friction based braking is necessary on

the other wheels

Conclusion

The energy efficiency of a conventional brake is only about 20 percent, with the remaining 80 percent of its energy being converted to heat through friction. The miraculous thing about regenerative braking is that it may be able to capture as much as half of that wasted energy and put it back to work. This reduces fuel consumption by 10 to 25 percent. Hence regenerative braking plays an important role in fuel consumption and also in the field of speed

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