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References

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	[[Category:Vehicle braking technologies]]		[[Category:Vehicle braking technologies]]
	~~[[Category:Locomotive parts]]~~
	[[Category:Electric vehicles]]		[[Category:Electric vehicles]]

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References

← Older revision		Revision as of 15:11, 4 May 2007
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	[[Category:Locomotive parts]]		[[Category:Locomotive parts]]
	[[Category:Electric vehicles]]		[[Category:Electric vehicles]]

	~~[[cs:Rekuperace]]~~
	~~[[de:Nutzbremse]]~~
	~~[[ko:회생 제동]]~~
	~~[[ja:回生ブレーキ]]~~
	~~[[no:Regenerativ bremsing]]~~
	~~[[pl:Hamowanie rekuperacyjne]]~~
	~~[[pt:Frenagem regenerativa]]~~
	~~[[ru:Рекуперативное торможение]]~~
	~~[[sk:Rekuperácia (dopravný prostriedok)]]~~
	~~[[zh:再生制動]]~~

62.87.120.166: /* Use in motor sport */

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Use in motor sport

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	==Use in motor sport==		==Use in motor sport==
	The governing body of international [[motor sport]], the [[FIA]], has allowed the use of 60 kW "Kinetic Energy Recovery Systems" (KERS), in the regulations for the [[2009 Formula One season]].<ref>~~{{cite news \| first = \| last = \| author = \| coauthors =\| url =~~http://www.fia.com/resources/documents/1151088479__2009_F1_TECHNICAL_REGULATIONS.pdf~~\| title =~~2009 Technical Regulations Released by FIA~~\| work = \| publisher =FIA \| pages = \| page = \| date =2006-12-22 \| accessdate =2006-12-22 \| language = }}~~</ref><ref>[http://www.evworld.com/syndicated/evworld_article_1160.cfm EVWorld article: ''Formula One: 'Braking' New Ground'']</ref>		The governing body of international [[motor sport]], the [[FIA]], has allowed the use of 60 kW "Kinetic Energy Recovery Systems" (KERS), in the regulations for the [[2009 Formula One season]].<ref>[http://www.fia.com/resources/documents/1151088479__2009_F1_TECHNICAL_REGULATIONS.pdf 2009 Technical Regulations Released by FIA]</ref><ref>[http://www.evworld.com/syndicated/evworld_article_1160.cfm EVWorld article: ''Formula One: 'Braking' New Ground'']</ref>

	== See also ==		== See also ==

62.87.120.166 at 15:09, 4 May 2007

2007-05-04T15:09:41Z

New page

A '''regenerative brake''' is a mechanism that reduces [[vehicle]] speed by converting some of its [[kinetic energy]] into electrical energy. This electrical energy is then stored for future use or fed back into a power system for use by other vehicles.

Regenerative brakes in electric [[railway]] vehicles feed the generated electricity back into the [[Railway electrification system|supply system]]. In [[Battery electric vehicle|battery electric]] and [[hybrid vehicle|hybrid electric]] vehicles, the energy is stored in a [[battery (electricity)|battery]] or bank of [[capacitors]] for later use.

Regenerative braking should not be confused with ''[[Regenerative brake#Comparison of Dynamic and Regenerative Brakes|dynamic braking]]'', which dissipates the electrical energy as heat.

Traditional [[friction]]-based braking is still used with regenerative braking for the following reasons:<br />
* The regenerative braking effect rapidly reduces at lower speeds.
* The amount of electrical energy capable of dissipation is limited by either the capacity of the supply system to absorb this energy or on the state of charge of the battery or capacitors. No regenerative braking effect can occur if another electric vehicle on the same supply system is not currently drawing power or if the battery or capacitors are already charged. For this reason, it is normal to also incorporate Dynamic Braking to absorb the excess energy.

==The motor as a brake==

Regenerative braking utilizes the fact that an electric motor can also act as a [[Electrical generator|generator]]. The vehicle's electric [[traction motor]] is reconnected as a generator during braking and its output is connected to an electrical load. It is this load on the motor that provides the braking effect.<br />

An early example of this system was the [[Energy Regeneration Brake]], developed in 1967 for the [[Amitron]]. This was a completely [[Battery electric vehicle|battery]] powered urban [[concept car]] whose batteries were recharged by regenerative braking, thus increasing the range of the automobile <ref> Time Magazine, Business Section, ''Next: the Voltswagon?'', December 22, 1967. </ref>.

===Electric railway vehicle operation===

During braking, the traction motor connections are altered to turn them into electrical generators. The motor fields are connected across the main traction generator (MG) and the motor armatures are connected across the load. The MG now excites the motor fields. The rolling locomotive wheels turn the motor armatures, and the motors act as generators. Either sending the generated current through onboard resistors ([[dynamic braking]]) or back into the supply (regenerative braking) provides the braking load.

For a given direction of travel, current flow through the motor armatures during braking will be opposite to that during motoring. Therefore, the motor exerts [[torque]] in a direction that is opposite from the rolling direction.<br />Braking effort is proportional to the product of the magnetic strength of the field windings, times that of the armature windings.

==Comparison of Dynamic and Regenerative Brakes==
{{main|Dynamic brake}}

Dynamic brakes ("rheostatic brakes" in the UK), unlike Regenerative Brakes, dissipate the electric energy as heat by passing the current through large banks of variable [[resistor]]s. Vehicles that use dynamic brakes include [[forklift]]s, [[Diesel-electric]] [[locomotive]]s and [[streetcar]]s. If designed appropriately, this heat can be used to warm the vehicle interior. If dissipated externally, large [[radiator]]-like cowls are employed to house the resistor banks.

The main disadvantage of regenerative brakes when compared with dynamic brakes is the need to closely match the generated current with the supply characteristics. With DC supplies, this requires that the voltage be closely controlled. Only with the development of power electronics has this been possible with AC supplies, where the supply frequency must also be matched (this mainly applies to locomotives where an AC supply is [[rectifier|rectified]] for DC motors).

A small number of [[mountain railway]]s have used [[3-phase]] power supplies and 3-phase [[induction motors]]. This results in a near constant speed for all trains as the motors rotate with the supply frequency both when motoring and braking.

==Use in motor sport==
The governing body of international [[motor sport]], the [[FIA]], has allowed the use of 60 kW "Kinetic Energy Recovery Systems" (KERS), in the regulations for the [[2009 Formula One season]].<ref>{{cite news | first = | last = | author = | coauthors =| url =http://www.fia.com/resources/documents/1151088479__2009_F1_TECHNICAL_REGULATIONS.pdf| title =2009 Technical Regulations Released by FIA| work = | publisher =FIA | pages = | page = | date =2006-12-22 | accessdate =2006-12-22 | language = }}</ref><ref>[http://www.evworld.com/syndicated/evworld_article_1160.cfm EVWorld article: ''Formula One: 'Braking' New Ground'']</ref>

== See also ==

* [[Brake (railway)]]
* [[Electromagnetic brake]]
* [[Dynamic braking]]
==References==
<references />

[[Category:Vehicle braking technologies]]
[[Category:Locomotive parts]]
[[Category:Electric vehicles]]

[[cs:Rekuperace]]
[[de:Nutzbremse]]
[[ko:회생 제동]]
[[ja:回生ブレーキ]]
[[no:Regenerativ bremsing]]
[[pl:Hamowanie rekuperacyjne]]
[[pt:Frenagem regenerativa]]
[[ru:Рекуперативное торможение]]
[[sk:Rekuperácia (dopravný prostriedok)]]
[[zh:再生制動]]

← Older revision		Revision as of 15:11, 4 May 2007
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	== See also ==		== See also ==

	* [[Brake (railway)]]
	* [[Electromagnetic brake]]		* [[Electromagnetic brake]]
	* [[Dynamic braking]]		* [[Dynamic braking]]

	==References==		==References==
	<references />		<references />

Regenerative braking - Revision history

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62.87.120.166 at 15:09, 4 May 2007