Electric Technology Explained: Part-2 How regenerative braking works and the benefits
Published On Dec 07, 2019
In part I of EV technology, we covered an electric drive in a commercial vehicle. In the second part of our ongoing electric technology stories, we look at the regenerative braking technology and the vital role it plays in an EV.
What is Regenerative Braking?
Regenerative Braking (RB) is a type of mechanism that recovers the energy lost during braking. RB mechanism slows down a vehicle by using the rotating motion of the wheels and convert the energy from the motion into electricity that can be either be fed to the vehicle battery directly or stored in a battery cell.
This technology is not an entirely new innovation; in fact, this technology even precedes the usage of the first mass-produced internal combustion engine-powered vehicles. The early examples of a regenerative braking system is traced back to the 1890s when Louis Antoine Krieger first converted the front-wheel-drive horse-drawn cabs in Paris. This mechanism called the Krieger electric landaulet had a drive motor in each front wheel with a second set of parallel windings (bifilar coil) for regenerative braking. Since then, several innovations and developments have taken in the field of RB and this technology has found extensive use in locomotive design and applications. Nearly all trains use some RB to generate electricity, which used for charging batteries that run various electrical equipment like lights, fans, etc.
However, for the most part of the previous century, all RB mechanisms relied heavily on manual processes, and it was only with the arrival of advanced software solutions since the late 1960s when these systems started becoming more and more automated. Today, RB has found considerable acceptance across the locomotive and automobile industry, and its usage remains to grow at a substantial pace globally. The ‘Mild Hybrid Technology’ uses regenerative braking to create electricity used for various purposes.
How regenerative braking works?
At the core of any RB mechanism is the most basic rule of production of electricity and the functioning of an electric motor. It is known that an electric current that is running through a wire creates a magnetic field. If a permanent magnet in the vicinity of the magnetic field created by the electric wire (that has been formed into a loop), a torque starts getting a build up in the system that eventually makes the looped wire spinning, and that gives an electric motor. If this process is reverse, then this same motor will become a generator, and instead of consuming current, it will start creating it.
Let’s look at how ‘braking’ comes into the picture. Inside the aforementioned electric motor/ generator, the number of magnetic fields that are created cause resistance to build up, it is this resistance that eventually translates into the slowing down of the vehicle, thus regenerative braking in the system.
Today, advanced forms of these electric motors are used at each wheel on an all-electric vehicle or they alongside an internal combustion engine-powered vehicle. When the wheels are moving, these motors are designed to move along in the direction of the rotation of the wheels; however, the moment a vehicle starts to brake or there are no throttle inputs, these motors start getting the above-mentioned resistance built up inside them creating electricity. This mechanism primarily utilizes the momentum of a moving vehicle to recover energy that would be otherwise be lost to the outside environment in the form of heat through the brake discs.
Benefits Regenerative System:
Regeneration through any regenerative braking system in an automobile can help towards substantially extending the life of the braking system. This is mainly due to the parts that do not wear as quickly.
Driving in a city or congested traffic, a staggering 62.5% of energy is lost to the environment as heat under frequent braking. With most of this wasted energy essentially coming through the burning of fuel (in a conventional vehicle) or loss of battery power in an electric vehicle. A smartly designed regenerative braking system can save a staggering amount of fuel 23% saving in fuel consumption.
Any regenerative system involves a tiny number of accessories that are lightweight and easy to maintain. With lower fuel consumption and a decline in the waste heat generation, the regenerative braking mechanism offers an advantage of lower emissions compared to a conventional vehicle.
The transportation industry consumes more than 20% of global energy, of which the urban transit consumes a staggering 40% or more. Usage of regenerative braking systems can increase vehicle driving ranges up to 105 or more. Regenerative braking systems can be retrofitted; however, they should be suitably governed by regulations.