Regenerative braking
Similarly, with rheostatic brakes, energy is recovered by using electric motors as generators but is immediately dissipated as heat in resistors.
Early examples of this system in road vehicles were the front-wheel drive conversions of horse-drawn cabs by Louis Antoine Krieger in Paris in the 1890s.
The Krieger electric landaulet had a drive motor in each front wheel with a second set of parallel windings (bifilar coil) for regenerative braking.
[7] The Orwell Electric Truck introduced by Ransomes, Sims & Jefferies in England during WW1 used regenerative braking switched in by the driver.
Slowing the speed of the cars or keeping it in control on descending gradients, the motors worked as generators and braked the vehicles.
[clarification needed][11] Following a serious accident at Rawtenstall, an embargo was placed on this form of traction in 1911;[12] the regenerative braking system was reintroduced twenty years later.
[citation needed] Electric cars used regenerative braking since the earliest experiments, but this initially required the driver to flip switches between various operational modes in order to use it.
Improvements in electronics allowed this process to be fully automated, starting with 1967's AMC Amitron experimental electric car.
[18] Designed by Gulton Industries[19] the motor controller automatically began battery charging when the brake pedal was applied.
Many modern hybrid and electric vehicles use this technique to extend the range of the battery pack, especially those using an AC drive train (most earlier designs used DC power).
[20] The Delhi Metro reduced the amount of carbon dioxide (CO2) released into the atmosphere by around 90,000 tons by regenerating 112,500 megawatt hours of electricity through the use of regenerative braking systems between 2004 and 2007.
It was expected that the Delhi Metro would reduce its emissions by over 100,000 tons of CO2 per year once its phase II was complete, through the use of regenerative braking.
[22] A form of what can be described as regenerative braking is used on some parts of the London Underground, achieved by having small slopes leading up and down from stations.
This heat can be used to warm the vehicle interior, or dissipated externally by large radiator-like cowls to house the resistor banks.
These two locomotives ran the steam water over the resistor packs, as opposed to air cooling used in most dynamic brakes.
In areas where there is a constant need for power unrelated to moving the vehicle, such as electric train heat or air conditioning, this load requirement can be utilized as a sink for the recovered energy via modern AC traction systems.
This method has become popular with North American passenger railroads where head end power loads are typically in the area of 500 kW year round.
Kinetic energy recovery systems (KERS) were used for the motor sport Formula One's 2009 season, and are under development for road vehicles.
[31] Xtrac and Flybrid are both licensees of Torotrak's technologies, which employ a small and sophisticated ancillary gearbox incorporating a continuously variable transmission (CVT).
[35] The second was less than a week later when a BMW Sauber mechanic was given an electric shock when he touched Christian Klien's KERS-equipped car during a test at the Jerez circuit.
McLaren Mercedes became the first team to win a F1 GP using a KERS equipped car when Lewis Hamilton won the 2009 Hungarian Grand Prix on 26 July 2009.
At the following race, Lewis Hamilton became the first driver to take pole position with a KERS car, his teammate, Heikki Kovalainen qualifying second.
It was the first time that KERS contributed directly to a race victory, with second placed Giancarlo Fisichella claiming "Actually, I was quicker than Kimi.
[41] The fail-safe settings of the brake-by-wire system that now supplements KERS came under examination as a contributing factor in the fatal crash of Jules Bianchi at the 2014 Japanese Grand Prix.
Peugeot planned to campaign the car in the 2009 Le Mans Series season, although it was not capable of scoring championship points.
[53] Peugeot was the first manufacturer to unveil a fully functioning LMP1 car in the form of the 908 HY at the 2008 Autosport 1000 km race at Silverstone.
The United States Environmental Protection Agency, working with students from the University of Michigan, developed the hydraulic Regenerative Brake Launch Assist (RBLA).
[61] Power consumption is reduced by regenerative braking on streetcars (AE) or trams (CE) in Oranjestad, Aruba.
Designed and built by TIG/m Modern Street Railways in Chatsworth, USA,[62] the vehicles use hybrid/electric technology: they do not take their power from external sources such as overhead wires when running but are self-powered by lithium batteries augmented by hydrogen fuel cells.
This can be represented by: A diagram by the United States Department of Energy (DoE) shows cars with internal combustion engines as having efficiency of typically 13% in urban driving, 20% in highway conditions.
