12-04-2012, 05:00 PM
Flywheel based Regenerative Braking
Flywheel based Regenerative Braking.pptx (Size: 2.17 MB / Downloads: 221)
What is Regenerative Braking or KERS
One of the key feature of Electric and hybrid vehicle.
KERS (Kinetic Energy Recovery System) technology takes a moving vehicle’s kinetic energy, which is otherwise wasted during braking, stores it, and then releases it back into the drivetrain as the vehicle accelerates.
As the name suggests in such brake mechanisms energy lost in conventional brake due to friction is converted to some form that can be reused again
Scope for KERS..?
On an average automobile brakes accounts for around 50% of the total losses that occur in an urban vehicle. Hence making it the largest share holder of the total energy lost.
The regenerative braking captures about 70% of the kinetic energy produced during braking.
Fully loaded medium sized Diesel truck weighing 25 tons, running at 30 km/hr. for an urban service truck which is supposed to cover a distance of 10 km, with expected stop at every 200 m due to traffic and service compulsions, can have a loss of about 60% only due to braking.
Advantages of Regenerative Braking
Only “waste energy” is utilized.
Increases fuel economy by 25-45%.
Wear Reduction, So brakes life increases.
CO2 emissions also decreases because of higher fuel economy.
e.g.-DMRC stopped the emission of 90,004 tonnes of carbon dioxide from 2004 to 2007 by adoption of regenerative braking systems in the Delhi Metro trains.
Prerequisites for Understanding KERS…..
CVT-Continuously Variable Transmissions don't have a gearbox with a set number of gears, which means they don't have interlocking toothed wheels. The most common type of CVT operates on an ingenious pulley system that allows an infinite variability between highest and lowest gears with no discrete steps or shifts.
Hybrid Vehicle-The most basic definition of a hybrid vehicle is one that uses two methods of providing power to the wheels.
The different categories are:
1. Micro hybrids, which could be based on a 12 Volt Belted Alternator Starter system, approximately 1 to 5 kW.
2. Mild hybrids which are the next step in hybridization enabling additional features such as regenerative braking and launch assist.,is in the range from 5 to 20 kW.
3. Full hybrid, which uses the same features as the two earlier mentioned hybrid types but it, has a greater installed electric power than the other two ranging from 20 kW to more than 100kW and system voltages up to 500 Volts or even more.
Types of Regenerative braking on HESS basis
There are basically 3 types of regenerating Braking possible on the basis of HESS (Hybrid Energy Storage Systems)-
1.Mechanical or flywheel based
2.Hydraulic based
3.Electrical-
3.a –Battery
3.b-Battery with Ultra Capacitor
3.c-Battery ,Ultra Capacitor, Switch and BMS
Hydraulic KERS
Hydraulic systems are used to mechanically store energy from a vehicle in motion. Hydraulic accumulators incorporated in passenger cars and buses store and provide energy.