thinktank Sept 2013 | Page 4

KINETIC ENERGY RECOVERY SYSTEM

(KERS)

Kimi Räikkönen took the lead of the 2009 Belgian Grand Prix with a KERS-aided overtake and subsequently won the race.

he word KERS stands for Kinetic Energy Recovery System. It is a collection of parts which takes some of the kinetic energy of a vehicle under deceleration i.e. under braking, stores this energy & then releases this stored energy back into the drive train of vehicle.

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.

KERS is simple, you need a component for generating the power, one for storing it and another to control it all. Thus KERS has three main components: The MGU, the PCU and the batteries/flywheel.

A motor-generator set may consist of distinct motor and generator machines coupled together. The MGU 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.

The PCU 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.

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. KERS stores 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.

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. 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.

Thus KERS with FES (Flywheel Energy Storage) provides much higher power output and energy efficiency than electrical type KERS.

Thus it is a technology for the present and the future because it is environment-friendly, reduces emissions & fuel consumption and increases efficiency. Whatever is the waste energy in braking or deceleration, can be used efficiently for the use again and thus we can have more power for acceleration.

There are two basic types of KERS, Electrical and Mechanical.

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. Super-capacitors can also be used to store electrical energy instead of batteries; they run cooler and are debatably more efficient.

The mechanical KERS system has a flywheel as the energy storage device replacing MGUs

NITISH SHINDE

T

4 SEPTEMBER, 2013

TT