kinetic energy recovery system (all types of KERS )
A Seminar on
PRESENTED BY-MR.LOHAR PRASAD MADHAV
GUIDED BY-PROF.AMIT KUMAR
DEPT OF MECHANICAL ENGINEERING
EXAM SEAT NO-T121150877
TYPES OF KERS
ADVANTAGES OF KERS
APPLICATIONS OF KERS
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.
WHAT IS KERS?
The acronym KERS stands for Kinetic Energy Recovery System.
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 a 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 way to store and then return energy to the
power train and
Second, a place to store this energy.
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: The MGU, the PCU
and the batteries/flywheel.
While a motor-generator set may consist of distinct motor and
generator machines coupled together, a single unit motor-
generator will have both rotor coils of the motor and the generator
wound around a single rotor, and both coils share the same outer
field coils or magnets 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. Managing the
battery is critical as the efficiency of a pack of Li-
ion cells will drop if one cell starts to fail. A failing
cell can overheat rapidly and cause safety issues.
As with all KERS components the PCU needs
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:
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 engines
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
The most difficult part in designing electrical KERS is how to
store the electrical energy. Most racing systems use a lithium
battery, which is essentially a large mobile phone battery.
Batteries become hot when charging them so many of
the KERS cars have more cooling ducts since charging
will occur multiple times throughout a race.
Super-capacitors can also be used to store electrical
energy instead of batteries; they run cooler and are
debatably more efficient.
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.
The kinetic energy of the vehicle ends up as kinetic energy of a rotating
flywheel through the use of shafts and gears.
Unlike electrical KERS, this method of storage prevents the need to transform
energy from one type to another. Each energy conversion in electrical KERS
brings its own losses and the overall efficiency is poor compared to mechanical
To cope with the continuous change in speed ratio between the flywheel and
road-wheels, a continuously variable transmission (CVT) is used, which is
managed by an electro-hydraulic control system. A clutch allows disengagement
of the device when not in use.
Braking at the wheels dissipates the kinetic energy of the vehicle
that is therefore completely lost. Conversely, KERS may store the
kinetic energy of the vehicle during braking and return it under
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.
The CVT is used because the ratios of vehicle and flywheel speed
are different during a braking or an acceleration event. can change
sleeplessly through an infinite number of effective gear ratios
between maximum and minimum values. This contrasts with other
mechanical transmissions that offer a fixed number of gear ratios.
ADVANTANGE OF MECHANICAL
KERS OVER ELECTRICAL KERS
Battery-based electric hybrid systems require a
number of energy conversions each with
corresponding efficiency losses. On reapplication
of the energy to the driveline, the global energy
conversion efficiency is 31–34%. The mechanical
hybrid system storing energy mechanically in a
rotating fly wheel eliminates the various energy
conversions and provides a global energy
conversion efficiency exceeding 70%, more than
twice the efficiency of an electric system.
ADVANTAGES OF KERS
This potential advantages and features of this
technology in the field of automobiles are:
High power capability
Light weight and small size
Long system life of upto 250,000 kms
A truly green solution
High efficiency storage and recovery
Low embedded carbon content
CURRENT APPLICATIONS OF
A consortium led by a Jaguar Land Rover is developing a
flywheel-hybrid system that it says boosts performance by 60
kilowatts (about 80 horsepower) while improving fuel
efficiency 20 percent. Jaguar is testing its purely mechanical
flywheel system, which reportedly weighs 143 pounds, in an
prototype XF sedan.
At the 2011North American International Auto Show Porsche
unveiled a RSR variant of their Porsche 918 concept car
which uses a flywheel-based KERS system that sits beside the
driver in the passenger compartment and boosts the dual
electric motors driving the front wheels and the 565 BHP V8
gasoline engine driving the rear to a combined power output
of 767 BHP.
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
Sreevalsan S Menon, “Design And Analysis Of Kinetic Energy Recovery System In
Bicycles”, Vol. 2, Issue 8, August 2013, International Journal of Innovative Research
in Science, Engineering and Technology ISSN: 2319-8753  pp 1029
Kevin Ludlum, “Optimizing Flywheel Design for use as a Kinetic Energy Recovery
System for a Bicycle”, 3/6/13  pp 1029
Alberto. Boretti, “A fun-to-drive, economic and environmental friendly mobility
solution”, Journal of power technologies 93 (4) -2013 pp 1030
Mugunthan, U. Nijanthan, “Design & Fabrication of Mechanism for Recovery of
Kinetic Energy in Bicycle Using Flywheel”, ISSN 2250-2459, ISO 9001:2008 Certified
Journal, Volume 5, Issue 5, May 2015, International Journal of Emerging Technology
and Advanced Engineering pp 1029