Seminar on

Kinetic Energy Recovery System

(KERS)

ABHILASH A 1NH14MMD01

CONTENTS

• KERS- INTRODUCTION• BASIC ELEMENTS• WORKING PRINCIPLE• TYPES OF KERS• ADVANTAGES• LIMITATIONS• CONCLUSION• REFERENCES

KERS Introduction• The acronym KERS stands for Kinetic Energy Recovery

System.• KERS is a collection of parts which takes some of the

kinetic energy of a vehicle under deceleration, stores this energy and then releases this stored energy back into the drive train of the vehicle, providing a power boost to that vehicle.

• For the driver, it is like having two power sources at his disposal, one of the power sources is the engine while the other is the stored kinetic energy.

• Kinetic energy recovery systems (KERS) store energy when the vehicle is braking and return it when accelerating.

• During braking, energy is wasted because kinetic energy is mostly converted into heat energy or sometimes sound energy that is dissipated into the environment.

• Vehicles with KERS are able to harness some of this kinetic energy and in doing so will assist in braking.

• By touch of a button, this stored energy is converted back into kinetic energy giving the vehicle extra boost of power.

BASIC ELEMENTS OF KERS

• First, a place to store this energy.• Second, a way to store and then return energy to

the power train and,Thus KERS systems have three main components:

1. The MGU, 2. The PCU and 3. The batteries/flywheel.

MGU (MOTOR-GENERATOR UNIT)

• Its a single unit which has both motor-generator rotor coils wound around a single rotor, and both coils share the same outer field coils working in two modes.

• The MGU both creates the power for the batteries when the car is braking, then return the power from the batteries to add power directly to the engine, when the KERS button is deployed.

PCU (Power Control Unit)• It serves two purposes, firstly to invert & control

the switching of current from the batteries to the MGU and secondly to monitor the status of the individual cells with the battery.

Power Storage Unit (Flywheel/Batteries)

• It stores power for immediate usage and gives power as and when required. Flywheel used in Mechanical KERS and Batteries are used in Electrical KERS.

WORKING PRINCIPLE• Basically, it’s working principle involves storing the

energy involved with deceleration and using it for acceleration. That is, when a car breaks, it dissipates a lot of kinetic energy as heat. The KERS tries to store this energy and converts this into power, that can be used to boost acceleration.

• A standard KERS operates by a ‘charge cycle and a ‘boost cycle’. As the car slows for a corner, an actuator unit captures the waste kinetic energy from the rear brakes. This collected kinetic energy is then passed to a Central Processing Unit (CPU) and onto the storage unit. The storage unit are positioned centrally to minimize the impact on the balance of the car.

TYPES OF KERS

• There are two basic types of KERS systems:• Electrical• Mechanical

• The main difference between them is in the way they convert the energy and how that energy is stored within the vehicle.

ELECTRICAL KERS• In electrical KERS, braking rotational force is captured by an

electric motor / generator unit (MGU) mounted to the engines crankshaft.

• This MGU takes the electrical energy that it converts from kinetic energy and stores it in batteries. The boost button then summons the electrical energy in the batteries to power the MGU.

MECHANICAL KERS

• The mechanical KERS system has a flywheel as the energy storage device and it does away with MGUs by replacing them with a transmission to control and transfer the energy to and from the driveline.

• The system utilizes a flywheel as the energy storage device and a Continuously Variable Transmission (CVT) to transfer energy to and from the driveline to the rotating flywheel.

• The transfer of the vehicle kinetic energy to the flywheel kinetic energy reduces the speed of the vehicle and increases the speed of the flywheel. The transfer of the flywheel kinetic energy to the vehicle kinetic energy reduces the speed of the flywheel and increases the speed of the vehicle.

ADVANTANGE OF MECHANICAL KERS OVER ELECTRICAL KERS

• In electrical KERS , energy has to be converted twice , where as in Mechanical no need of conversion. Hence electrical energy conversion efficiency is 31- 34 % where as in mechanical KERS its 70%

• Energy lose in Electrical KERS is more , Whereas not so much in Mechanical KERS

• Lithium-ion batteries take 1-2 hours to charge completely due to low specific power hence not good for F1 , so they use Super Capacitor.

ADVANTAGES OF KERS This potential advantages and features of this technology in the

field of automobiles are:

• High power capability• Reduced CO2 Emissions/Pollutants• Light weight and small size• Long system life of upto 250,000 kms• Completely safe• A truly green solution• High efficiency storage and recovery• Low embedded carbon content• Low cost in volume manufacture

KERS in Road Cars

• Transport Buses in Sverdon, Switzerland (1950)

• Honda Civic Hybrid(2002)• Ford Escape Hybrid(2005)• Jaguar XF sedan (Prototype)• Porsche 918 RSR variant concept car (2011)• KERS in Road Cars

Limitations of KERS

• Only one KERS for car which has only one braking system.• 60 kw is the maximum input and output power of the KERS

system. • The energy recovery system is functional only when the car

is moving.• The recovery system must be controlled by the same

electronic control unit.• If in case the KERS is connected between the differential and

the wheel the torque applied to each wheel must be same.• It is very costly. Engineers are trying hard to make it more

cost effective.

CONCLUSION

• It’s a technology for the present and the future because it’s environment-friendly, reduces emissions, has a low production cost, increases efficiency and is highly customizable and modifiable. Adoption of a KERS may permit regenerative braking and engine downsizing as a means of improving efficiency and hence reducing fuel consumption and CO2 emissions.

• The KERS have major areas of development in power density, life, simplicity, effectiveness and first and foremost the costs of the device. Applications are being considered for small, mass-production passenger cars, as well as luxury cars, buses and trucks.

REFERENCE

• Wikipedia• autosport.com• saeindia.org • Cross, Douglas. "Optimization of Hybrid Kinetic

Energy Recovery Systems (KERS) for Different Racing Circuits." SAE Digital Library. SAE International. Web. 25 Sept. 2009.

• Sorniotti, Aldo, and Massimiliano Curto. "Racing Simulation of a Formula 1 Vehicle with Kinetic Energy Recovery System." SAE Digital Library. SAE International. Web. 25 Sept. 2009.

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