What is Electric Motor ?

interior, or dissipated externally by large radiator-like cowls to house the resistor banks

General Electric's experimental 1936 steam turbine locos featured true regeneration. These two locomotives ran the steam

water over the resistor packs, as opposed to air cooling used in most dynamic brakes. This energy displaced the oil normally

burned to keep the water hot, and thereby recovered energy that could be used to accelerate again.[19]

The main disadvantage of regenerative brakes when compared with dynamic brakes is the need to closely match the

generated current with the supply characteristics and increased maintenance cost of the lines. With DC supplies, this requires

that the voltage be closely controlled. The AC power supply and frequency converter pioneer Miro Zorič and his first AC power

electronics have also enabled this to be possible with AC supplies. The supply frequency must also be matched (this mainly

applies to locomotives where an AC supply is rectified for DC motors).

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. Using HEP loads in this way has prompted recent electric

locomotive designs such as the ALP-46 and ACS-64 to eliminate the use of dynamic brake resistor grids and also eliminates any need for any external power

infrastructure to accommodate power recovery allowing self-powered vehicles to employ regenerative braking as well.

A small number of steep grade railways have used 3-phase power supplies and induction motors. This results in a near constant speed for all trains, as the motors

rotate with the supply frequency both when driving and braking.

Conversion to mechanical energy

Kinetic energy recovery systems

Kinetic energy recovery systems (KERS) were used for the motor sport Formula One's 2009 season, and are under development for road vehicles. KERS was

abandoned for the 2010 Formula One season, but re-introduced for the 2011 season. By 2013, all teams were using KERS with Marussia starting use for the 2013

season.[20] One of the main reasons that not all cars used KERS immediately is because it raises the car's center of gravity, and reduces the amount of ballast that is

available to balance the car so that it is more predictable when turning.[21] FIA rules also limit the exploitation of the system. The concept of transferring the vehicle's

kinetic energy using flywheel energy storage was postulated by physicist Richard Feynman in the 1950s[22] and is exemplified in such systems as the Zytek, Flybrid,[23]

Torotrak[24][25] and Xtrac used in F1. Differential based systems also exist such as the Cambridge Passenger/Commercial Vehicle Kinetic Energy Recovery System

(CPC-KERS).[26]