Regenerative brake

The regenerative braking regenerative braking or when braking wins a motor vehicle, the kinetic energy as electrical energy back. This is achieved in an electric or hybrid vehicles, characterized in that the drive electromotor operates as a generator; by the mechanical power of the braking effect is achieved. In contrast to the pure resistance brake recovered from the kinetic energy of electric energy is not lost in the regenerative brake.

A regenerative brake wear-free, the regeneration occurs in the power supply cable or overhead line or an energy storage device, such as a battery or high-performance capacitor. This makes it a special design of the electric motor brake. It is used for electric vehicles, hybrid electric vehicles, and Nitro car with electricity storage, electric locomotives, railcars, trams, trolleybuses, conveyors in mining or all cable cars in particular ore transport and ropeways.

Rail vehicles

Electric drive

Even in the early days of electric railways, some locomotives were equipped with regenerative braking, for example, the SBB Ce 6 /8 " crocodile ".

During braking, the traction motors are switched to generators. The electricity produced is in old conventional locomotives and railcars, which are operated with alternating current, over complex circuits headed back to the transformer and fed into the catenary. With this technique, first, a recovery of only about five percent of the energy consumed was possible, the braking force was also weak and irregular.

For three-phase railway systems, particularly the northern Italian network of about 1902 to 1976, but also some mountain railways such Gornergrat near Zermatt, much higher feedback gains were ( by 50 %) at a very reliable braking power with simple asynchronous reached ( see History of the electric drive of rail vehicles (Italy ) )

With traction converters equipped modern vehicles, the braking energy can exploit much better. The traction motors of the locomotive dine while the inverter with AC. This, in turn, convert the energy into alternating current which is stepped up and applied to the driving line. This circuit works in the entire speed range and up to the full power of the drive motors, and allows the recovery of about 25 to 30 percent of the energy required for driving.

AC overhead line networks can always absorb the power produced by locomotives in the normal case, since they are capable of energy recovery and the current in the entire railway power network can be used ( only with massive other problems there may be congestion, resulting in a power outage, such as in Switzerland on 22 June 2005). DC grids are only partially receptive, since they are not often capable of energy recovery; the injected current can then be used only locally - if no electricity is needed, can not be fed - the catenary voltage would rise otherwise inadmissible. In order to allow in DC systems, an intermediate storage of electrical energy, there are attempts, for example, with flywheels ( tram network Hannover). Modern DC and multi-system locomotives are equipped with braking resistors so that even in situations where the electric power can not be fed back, the wear- free electrical brakes may be used.

Trams can save (double layer capacitors) on board, in order to use the next time you start the braking energy in capacitors. Furthermore, there is the possibility to build capacitor stations along the routes in order to absorb the energy can.

Piston engines

So-called steam locomotives memory had a fire loose steam engine and " fueled " vapor which stood in industrial areas or in the vicinity of power plants available. They were used during maneuvering in industrial areas. This, as well as the similar, only with compressed air driven test models could change strategy and their machine for braking as a piston pump and so return a part of the braking energy into the boiler. The efficiency is limited principally by the laws of thermodynamics.

Road vehicles

Cars with electric, hybrid or Gyroantrieb are mostly used for regenerative braking in the situation. Perform the braking energy back into their accumulators, accumulators in buffering supercapacitors or flywheel.

Also, electric bikes are isolated to regenerative braking in the situation.

BMW has, inter alia, incorporated in the year 2003 for the majority of its vehicles under the heading of a EfficientDynamics Brake Energy Regeneration in its petrol and diesel vehicles. However, these are not a recovery in the real sense, but the loading of the aircraft battery is (if possible) only performed when the vehicle is in overrun ( engine braking ). Result, the power consumption of the generator is reduced in travel operation, which has a favorable effect on fuel consumption.

Racing

In Formula 1 since the 2009 season, a variant of regenerative braking, the so-called KERS used. Porsche has built a regenerative brake when race car 911 GT3 R Hybrid (2010), in which the energy generated is fed into a flywheel accumulator.