KInetic Energy Recovery System (KERS)

KERSKinetic Energy Recovery System

By: Akheel Ahamed 1OX09ME004

Guide: C.V. Raja Reddy Professor , Mechanical Dept T.O.C.E

KERS - Introduction

• The acronym KERS stands for Kinetic Energy Recovery System. The device recovers the kinetic energy that is present in the waste heat created by the car’s braking process. It stores that energy and converts it into power that can be called upon to boost acceleration.

• 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 stores this energy and converts this into power, Upto 80 BHP for 6.67 secs or 400 kj of energy can be stored.

KERS - History

• In development since 90’s . It was first introduced to the general public through the 2009 series of Formula one motor sport.

• KERS builders, Flybrid Systems demonstrated a working Formula One-spec device at the Autosport International show. (24kg , 400kj energy capacity, power boost-60kw).

• FIA introduced KERS in 2009 GP series to Increase Overtaking and also as defensive tool to block faster car

• But many F1 teams Opposed it , as it was an Expensive system, so it was banned in 2010 season

• But with improvements and increase in manufacturers for KERS it was reintroduced in 2011.

KERS - History

• In the parallel Universe of Stock/Commercial cars many hybrid manufactures like Honda and Toyota developed similar, but less powerful system (23 kw) in Civic and Prius.

• At the 2011North American International Auto Show, Porsche unveiled a RSR variant of their Porsche 918 concept car which uses a flywheel-based KERS

• A motorcycle racing company called KTM Racing, secretly tested this kinetic energy system in their vehicle, but they were banned as that system was illegal and unstable for motorcycles.

KERS – Working Schematics

Basic Elements of KERS

In essence a KERS systems is simple, you need a component for generating the power, one for storing it and another to control it all. Thus KERS systems have three main components: 1. The MGU (Motor/Generator Unit)2. The PCU (Power Control Unit)3. The batteries/flywheel. (Power Storage Unit)

Basic Elements of KERS

1. 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.

Basic Elements of KERS

2. Power Control Unit ( PCU ) It serves two purposes, to invert & control the switching of current from the batteries to the MGU and to monitor the status of the individual cells with the battery.

Basic Elements of KERS

3. 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.

Types of KERS

The KERS can be divided in the way they convert the energy and how that energy is stored within the vehicle. Depending on this, KERS has two types: 1. Mechanical Kinetic Energy Recovery System2. Electrical Kinetic Energy Recovery System

Mechanical KERS

• The concept of transferring the vehicle’s kinetic energy using flywheel energy storage was postulated by physicist Richard Feynman in the 1950.

• 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.

Mechanical KERS

Mechanical KERS

VIDEO

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 which in turn powers boosts the driveline

Electrical KERS

Electrical KERS

VIDEO

Advantages of Mechanical KERSOver 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%

• 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.

• Chemical batteries heat up during charging process and could cause the batteries to lose energy over the cycle or worse even explode.

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

KERS in Formula One• KERS was introduced by the International Automobile

Federation (FIA) with a view to increase overtaking during Formula One Grand Prix races, as the boost button provides extra power. In effect, the KERS has also been used to act as a defensive tool to block a faster car, inhibiting overtaking.

• In the 2009 season KERS was not a huge success, the system had a FIA cap on the amount of energy that could be re-used, only 400kJ could be stored, which when used for 6.7s per lap, the car gained some 80hp. Thus although a 0.3s boost to lap times was achieved, the system was ultimately limited in its potential to improve lap times

KERS in Formula One - Features• A flywheel made of steel and carbon fibre that rotated at

over 60,000 RPM inside an evacuated chamber. and casing featured containment to avoid the escape of any debris.

• The flywheel was connected to the transmission of the car on the output side of the gearbox via several fixed ratios, a clutch and a Continuously Variable Transmission

• 80 BHP developed for 6.67 secs per lap reducing the circuit time by 3 – 4 secs, which can used all at a time or as and when required 60 kW power transmissions in either storage or recovery. 400 kJ of usable storage (after accounting for internal losses).A total system weighs 25kg.

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)

Advantages of KERS

• Reduced CO2 Emissions/Pollutants• Enhanced Performance• Environmentally Sound• High power capability• Light weight and small size with Long system life• Completely Safe and a Truly Green Solution• High efficiency Storage and Recovery

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, 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 and Trucks.

References• Presentation on KERS by Harsh Gupta.• Kinetic Energy Recovery System by means of Flywheel

Energy Storage by Cibulka, J.• Towards Sustainable Racing by Simon Watkins , RMIT

University.• Shell Engineering• Formula One • Torotrak• WikiPedia• http://www.oxbridgewriters.com/essays/engineering/

kers.php

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