ABHILASH A 1NH14MMD01
• KERS- INTRODUCTION
• BASIC ELEMENTS
• WORKING PRINCIPLE
• TYPES OF KERS
• The acronym KERS stands for Kinetic Energy Recovery
• 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
• During braking, energy is wasted because kinetic
energy is mostly converted into heat energy or
sometimes sound energy that is dissipated into the
• 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
• It stores power for immediate usage and gives
power as and when required. Flywheel used in
Mechanical KERS and Batteries are used in
• 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
• 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:
• The main difference between them is in the way
they convert the energy and how that energy is
stored within the vehicle.
• In electrical KERS, braking rotational force is captured by
an electric motor / generator unit (MGU) mounted to the
• 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.
• 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
• 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
• The energy recovery system is functional only when the car
• 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
• 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.
• 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.