2. Introduction to Regenerative Braking Systems
A regenerative brake is an apparatus, a device or system which allows a vehicle to recapture and store part of the kinetic energy that would otherwise be 'lost' to heat when braking. Or, A regenerative brake is a mechanism that reduces vehicle speed by converting some of its kinetic energy into a storable form of energy instead of dissipating it as heat as with a conventional brake. The captured energy is stored for future use or fed back into a power system for use by other vehicles.

Electrical regenerative brakes in electric railway vehicles feed the generated electricity back into the supply system. In battery electric and hybrid electric vehicles the energy is stored in a battery or bank of capacitors for later use.

Figure 1 (Regenerative brakes in a car) As the figure indicates the axle is coupled with the electric motor mechanically and the motor is connected to the battery (The blue arrows in the figure denote the power supplied by the batteries and the green arrows denotes the power supplied to the batteries for storage) Every time you step on your car's brakes, you're wasting energy. Physics tells us that energy cannot be destroyed. So when your car slows down, the kinetic energy that was propelling it forward has to go somewhere. Most of it simply dissipates as heat and becomes useless. That energy, which could have been used to do work, is essentially wasted. Is there anything that you, the driver, can do to stop wasting this energy? Not really. In most cars it's the inevitable byproduct of braking and there's no way you can drive a car without occasionally hitting the brakes. But automotive engineers have given this problem a lot of thought and have come up with a kind of braking system that can recapture much of the car's kinetic energy and convert it into electricity, so that it can be used to recharge the car's batteries. This system is called regenerative braking.
All throughout the country, gas prices are still climbing to numbers that seem to unhinge wallets, yet jaws even wider. Car advertisements now highlight gas mileage efficiency rather than the quality of steering and handling. Thus, the era of the Hybrid has begun, and with it, revolutions in saving power and energy have become the forefront innovations in recent cars. As hybrids rely primarily on the battery, recharging this mechanism to exhume the maximum power is vital to prolonging the existence of this car. One such way is via the braking system.
Everyone is quite familiar with the concept of friction, a force that resists the direction of motion and reduces the force causing that motion. Now the braking system of most hybrids transfers the torque from the wheels into the motor shaft through chains and gears. The electric motor inside, maintains the ability to convert electric energy into mechanical (normal) as well as mechanical energy, such as heat, a byproduct of friction, back into electric (regenerative). Located on the shaft of the motor, also known as a rotor, are magnets that move past electric coils on the stator, the stationary part of a motor.
This creates electricity which is delivered to the battery in the form of electrical energy. In laymen’s terms, this process is defined as turning the electric motor backwards to convert the mechanical energy into electric energy. The regenerative nature of the braking system and the conversion of mechanical energy into electrical energy are very efficient processes and contribute to saving the cars power
At present, these kinds of brakes are primarily found in hybrid vehicles like the Toyota Prius, and in fully electric cars, like the Tesla Roadster. In vehicles like these, keeping the battery charged is of considerable importance. However, the technology was first used in trolley cars and has subsequently found its way into such unlikely places as electric bicycles and even Formula One race cars. In a traditional braking system,