91948246 Regenerative Braking Ppt Final

7/28/2019 91948246 Regenerative Braking Ppt Final

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STVINCENT PALLOTTICOLL6 OF

ENGINRIN6AND TCHNOLOGY NAGPUR


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BRAKES

A BRAKE IS A MACHINE ELEMENT AND ITSPRINCIPLE OBJECTIVE IS TO ABSORB ENERGYDURING DECELERATION.

BY CONNECTING THE MOVING MEMBER TOSTATIONARY FRAME, NORMALLY BRAKECONVERTS KINETIC ENERGY TO HEAT ENERGY.

THIS CAUSES WASTAGE OF ENERGY AND ALSOWEARING OF FRICTIONAL LINING MATERIAL.


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DEFINITION

BRAKING METHOD IN WHICH THE MECHANICAL

ENERGY FROM THE LOAD IS CONVERTED INTO

ELECTRIC ENERGY AND REGENERATED BACK

INTO THE LINE IS KNOWN AS REGENERATIVE

BRAKING. THE MOTOR OPERATES AS GENERATOR.


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NECESSITY OF THE REGENERATIVE

BRAING SYSTEM

IN LOW-SPEED, STOP-AND-GO TRAFFIC WHERE LITTLEDECELERATION IS REQUIRED; THE REGENERATIVE BRAKINGSYSTEM CAN PROVIDE THE MAJORITY OF THE TOTAL BRAKING

FORCE. THIS VASTLY IMPROVES FUEL ECONOMY WITH AVEHICLE, AND FURTHER ENHANCES THE ATTRACTIVENESS OFVEHICLES USING REGENERATIVE BRAKING FOR CITY DRIVING.

AT HIGHER SPEEDS, TOO, REGENERATIVE BRAKING HAS BEENSHOWN TO CONTRIBUTE TO IMPROVED FUEL ECONOMY BY AS

MUCH AS 20%.


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REGENERATIVE BREAKING -

OVERVIEW

REGENERATIVE BRAKING IS USED TO

IMPROVE THE EFFICIENCY (FUEL ECONOMY)

OF:

ELECTRIC VEHICLESHYBRID VEHICLES

INDUSTRIAL APPLICATIONS

LOWERS OPERATION COST


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Batteries Motor

Brakes

Batteries MotorKineticEnergy


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WORKING

REGENERATIVE BRAKING SYSTEM IS THE WAY OF SLOWING VEHICLE BYUSING THE MOTORS AS BRAKES. INSTEAD OF THE SURPLUS ENERGY OFTHE VEHICLE BEING WASTED AS UNWANTED HEAT, THE MOTORS ACT ASGENERATORS AND RETURN SOME OF IT TO THE OVERHEAD WIRES ASELECTRICITY.

THE VEHICLE IS PRIMARILY POWERED FROM THE ELECTRICAL ENERGY

GENERATED FROM THE GENERATOR, WHICH BURNS GASOLINE. THISENERGY IS STORED IN A LARGE BATTERY, AND USED BY AN ELECTRICMOTOR THAT PROVIDES MOTIVE FORCE TO THE WHEELS.

THE REGENERATIVE BARKING TAKING PLACE ON THE VEHICLE IS A WAYTO OBTAIN MORE EFFICIENCY; INSTEAD OF CONVERTING KINETIC

ENERGY TO THERMAL ENERGY THROUGH FRICTIONAL BRAKING, THEVEHICLE CAN CONVERT A GOOD FRACTION OF ITS KINETIC ENERGY BACKINTO CHARGE IN THE BATTERY, USING THE SAME PRINCIPLE AS ANALTERNATOR.


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WEFi


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TYPES OF REGENERATIVE BRAKING

SYSTEM1. HYDRAULIC REGENERATIVE BRAKES

VEHICLE'S KINETIC ENERGY IS USED TO POWER A REVERSIBLE PUMP, WHICH SENDS

HYDRAULIC FLUID FROM A LOW PRESSURE ACCUMULATOR (A KIND OF STORAGE

TANK) INSIDE THE VEHICLE INTO A HIGH PRESSURE ACCUMULATOR. THE PRESSURE

IS CREATED BY NITROGEN GAS IN THE ACCUMULATOR, WHICH IS COMPRESSED AS

THE FLUID IS PUMPED INTO THE SPACE THE GAS FORMERLY OCCUPIED. THIS SLOWS

THE VEHICLE AND HELPS BRING IT TO A STOP.

2. FLY WHEELS

ROTATING PART OF THE ENGINE INCORPORATES A WHEEL WITH A VERY HEAVYMETAL RIM, AND THIS DRIVES WHATEVER MACHINE OR DEVICE THE ENGINE IS

CONNECTED TO. IT TAKES MUCH MORE TIME TO GET A FLYWHEEL-ENGINE TURNING

BUT, ONCE IT'S UP TO SPEED, THE FLYWHEEL STORES A HUGE AMOUNT OF

ROTATIONAL ENERGY.

3. USE IN COMPRESSED AIR

REGENERATIVE BRAKES COULD BE EMPLOYED IN COMPRESSED AIR CARS TO REFILL

THE AIR TANK DURING BRAKING. BY ABSORBING THE KINETIC ENERGY (NECESSARY

FOR BARKING), USING THE SAME FOR COMPRESSING THE AIR AND REUSE THESE

COMPRESSED AIR WHILE POWERING THE CAR.


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BRAKING PARAMETERS

Safe Interval Should Be > 3 seconds 6 seconds

Speed Distance Travelled For These Conditions > Good Marginal

25 m.p.h. 37 ft. per second 111 ft. 222 ft.



55 m.p.h. 81 ft. per second 243ft. 486 ft.



Safe Following Distance in Feet


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Regenerative Brakes Try To Slow Down The Vehicle And It Is Quite Difficult

To Bring It To Complete Halt.

In Cities Many A Times There Is Necessity To Bring The Vehicle To Complete Halt

Suddenly Due To Heavy Traffic

In Such Situation Use Of Regenerative Brakes Alone Is Dangerous

To Overcome This Issue Regenerative Braking System Is Accompanied With

Traditional Barking System.


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Traditional friction-based braking is used in conjunction with mechanical

regenerative braking for the following reasons:

The regenerative braking effect drops off at lower speeds; therefore thefriction brake is still required in order to bring the vehicle to a complete

halt. Physical locking of the rotor is also required to prevent vehicles from

rolling down hills.

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

Most road vehicles with regenerative braking only have power on some

wheels (as in a two-wheel drive car) and regenerative braking power only

applies to such wheels, so in order to provide controlled braking underdifficult conditions (such as in wet roads) friction based braking is

necessary on the other wheels.


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The amount of electrical energy capable of dissipation is limited by either the capacity

of the supply system to absorb this energy or on the state of charge of the battery or

capacitors. No regenerative braking effect can occur if another electrical component on

the same supply system is not currently drawing power and if the battery or capacitors

are already charged. For this reason, it is normal to also incorporate dynamic braking to

absorb the excess energy.

Under emergency braking it is desirable that the braking force exerted be the maximum

allowed by the friction between the wheels and the surface without slipping, over theentire speed range from the vehicle's maximum speed down to zero. The maximum

force available for acceleration is typically much less than this except in the case of

extreme high-performance vehicles. Therefore, the power required to be dissipated by

the braking system under emergency braking conditions may be many times the

maximum power which is delivered under acceleration. Traction motors sized to handlethe drive power may not be able to cope with the extra load and the battery may not be

able to accept charge at a sufficiently high rate. Friction braking is required to absorb

the surplus energy in order to allow an acceptable emergency braking performance.


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ADVANTAGES OF REGENERATIVE

BRAKING ACCOMPANIED WITH

CONVENTIONAL BRAKING

ENERGY CONSERVATION

WEAR REDUCTION

LOW FUEL CONSUMPTION

BRAKING IS NOT TOTAL LOSS

ENHANCED SAFETY OF DRIVER


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CONCLUSION

THE BEGINNING OF THE 21ST CENTURY COULD VERY WELL MARK THE FINAL

PERIOD IN WHICH INTERNAL COMBUSTION ENGINES ARE COMMONLY USED

IN CARS.

ALREADY AUTOMAKERS ARE MOVING TOWARD ALTERNATIVE ENERGYCARRIERS, SUCH AS ELECTRIC BATTERIES, HYDROGEN FUEL AND EVEN

COMPRESSED AIR.

REGENERATIVE BRAKING IS A SMALL, YET VERY IMPORTANT, STEP TOWARD

OUR EVENTUAL INDEPENDENCE FROM FOSSIL FUELS AND CAN OPEN A NEW

REALM IN SAFETY ON ROADS.


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THANK YOU...

91948246 Regenerative Braking Ppt Final

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