Regenerative braking - Revision history

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	[[Category:~~Done 2015-10-15~~]] [[Category:~~Automotive~~]]		[[Category:Automotive]]
			[[Category:Done 2018-06-01]]
	[[File:Flybrid_Systems_Kinetic_Energy_Recovery_System.jpg\|360px\|thumb\|right\|Figure 1. A regenerative brake.<ref>Wikimedia Commons. (October 3, 2015). ''Flybird Systems KERS'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/8/8e/Flybrid_Systems_Kinetic_Energy_Recovery_System.jpg</ref>]]		[[File:Flybrid_Systems_Kinetic_Energy_Recovery_System.jpg\|360px\|thumb\|right\|Figure 1. A regenerative brake.<ref>Wikimedia Commons. (October 3, 2015). ''Flybird Systems KERS'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/8/8e/Flybrid_Systems_Kinetic_Energy_Recovery_System.jpg</ref>]]
	<onlyinclude>'''Regenerative braking systems''' (RBSs) are a type of [[kinetic energy recovery system]] that transfers the [[kinetic energy]] of an object in motion into [[potential energy\|potential or stored energy]] to slow the [[vehicle]] down, and ~~increase~~ [[fuel efficiency]].</onlyinclude><ref>M. Bodie and K. Majeed, “Regenerative braking method,” 5,707,1151998.</ref> These systems are also called kinetic energy recovery systems. There are multiple methods of energy conversion in RBSs including spring, flywheel, electromagnetic and hydraulic. More recently, an electromagnetic-flywheel hybrid RBS has emerged as well. Each type of RBS utilizes a different energy conversion or storage method, giving varying efficiency and applications for each type.		<onlyinclude>'''Regenerative braking systems''' (RBSs) are a type of [[kinetic energy recovery system]] that transfers the [[kinetic energy]] of an object in motion into [[potential energy\|potential or stored energy]] to slow the [[vehicle]] down, and as a result increases [[fuel efficiency]].</onlyinclude><ref>M. Bodie and K. Majeed, “Regenerative braking method,” 5,707,1151998.</ref> These systems are also called kinetic energy recovery systems. There are multiple methods of energy conversion in RBSs including spring, flywheel, electromagnetic and hydraulic. More recently, an electromagnetic-flywheel hybrid RBS has emerged as well. Each type of RBS utilizes a different energy conversion or storage method, giving varying efficiency and applications for each type.

	RBSs are installed along the [[drive train]] or fitted to the drive wheels of a vehicle where they inhibit the motion of the wheels using [[magnetic field]]s or mechanical [[torque]]. These methods of motion inhibition allow [[energy]] to be generated under braking, as opposed to [[Braking\|friction brakes]] which simply waste away energy to slow the vehicle by turning the kinetic energy into [[thermal energy]]. Due to the maximum charging rate of the energy storage mechanisms, the braking force from a RBS is limited. Therefore, a traditional friction brake system is required to maintain the safe operation of a vehicle when heavy braking is necessary. RBS can improve fuel consumption and reduce the overall braking load taken on by the vehicles friction brakes, reducing the wear on the brake pads.<ref>Robert Bosch GmbH, “Regenerative braking Active safety - Regenerative Braking Systems,” Bosch Automotive Technology. [Online]. Available: http://www.bosch-automotivetechnology.com/en/de/component/SF_PC_AS_Regenerative-Braking-Systems_SF_PC_Active-Safety_2575.html. [Accessed: 27-Oct-2013].</ref><br />		RBSs are installed along the [[drive train]] or fitted to the drive wheels of a vehicle where they inhibit the motion of the wheels using [[magnetic field]]s or mechanical [[torque]]. These methods of motion inhibition allow [[energy]] to be generated under braking, as opposed to [[Braking\|friction brakes]] which simply waste away energy to slow the vehicle by turning the kinetic energy into [[thermal energy]]. Due to the maximum charging rate of the energy storage mechanisms, the braking force from a RBS is limited. Therefore, a traditional friction brake system is required to maintain the safe operation of a vehicle when heavy braking is necessary. RBS can improve fuel consumption and reduce the overall braking load taken on by the vehicles friction brakes, reducing the wear on the brake pads.<ref>Robert Bosch GmbH, “Regenerative braking Active safety - Regenerative Braking Systems,” Bosch Automotive Technology. [Online]. Available: http://www.bosch-automotivetechnology.com/en/de/component/SF_PC_AS_Regenerative-Braking-Systems_SF_PC_Active-Safety_2575.html. [Accessed: 27-Oct-2013].</ref><br />

	RBSs are used in almost every [[electric vehicle]]s and [[hybrid electric vehicle]]s. ~~As well~~, public transportation such as buses and bullet trains make use of RBSs ~~for~~ to decrease the environmental impacts of the transportation fleet and save money.<ref>R. Chicurel, “A compromise solution for energy recovery in vehicle braking,” Energy, vol. 24, no. 12, pp. 1029–1034, Jan. 1999.</ref>		RBSs are used in almost every [[electric vehicle]]s and [[hybrid car\|hybrid electric vehicle]]s. In addition, public transportation such as buses and bullet trains make use of RBSs to decrease the environmental impacts of the transportation fleet and save money.<ref>R. Chicurel, “A compromise solution for energy recovery in vehicle braking,” Energy, vol. 24, no. 12, pp. 1029–1034, Jan. 1999.</ref>

	==History==		==History==
	The idea of a brake that could take the kinetic energy it absorbs and turn it into potential energy for later use has been around since the late 1800s. Some of the early attempts of this technology were to install spring type RBS on front wheel drive bicycles or horse-drawn cabs.<ref>B. RIEDER, “Regenerative Braking System for Bicycles,” 2340641880.</ref><ref name=book1>W. W. Clark II and G. Cooke, Global Energy Innovation: Why America Must Lead. Praeger, 2011.</ref><br />		The idea of a brake that could take the kinetic energy it absorbs and turn it into potential energy for later use has been around since the late 1800s. Some of the early attempts of this technology were to install spring type RBS on front wheel drive bicycles or horse-drawn cabs.<ref>B. RIEDER, “Regenerative Braking System for Bicycles,” 2340641880.</ref><ref name=book1>W. W. Clark II and G. Cooke, Global Energy Innovation: Why America Must Lead. Praeger, 2011.</ref><br />

	The Baku-Tbilisi-Batumi railway started applying RBS in the early 1930s~~, this~~ is one example of early using of this technology in railway system.<ref name=book1/>		The Baku-Tbilisi-Batumi railway started applying RBS in the early 1930s. This is one example of early using of this technology in railway system.<ref name=book1/>

	In the 1950s, Swiss company Oerlikon developed the gyrobus, which utilized flywheel as its energy storage method. The effects of [[Gyroscopic motion\|gyroscopic motion]] on the bus soon resulted in it being discontinued.<ref>J. Hampl, “Concept of the Mechanically Powered Gyrobus,” Trans. Transp. Sci., vol. 6, no. 1, pp. 27–38, Jan. 2013.</ref>		In the 1950s, Swiss company Oerlikon developed the gyrobus, which utilized flywheel as its energy storage method. The effects of [[Gyroscopic motion\|gyroscopic motion]] on the bus soon resulted in it being discontinued.<ref>J. Hampl, “Concept of the Mechanically Powered Gyrobus,” Trans. Transp. Sci., vol. 6, no. 1, pp. 27–38, Jan. 2013.</ref>
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	=== Electromagnetic ===		=== Electromagnetic ===
	In electromagnetic system, the drive shaft of the vehicles is connected to an [[Electric generator\|electric generator]], which uses magnetic fields to restrict the rotation of the drive shaft, slowing the vehicle and generating electricity. In the case of electric and hybrid vehicles, the electricity generated is sent to the [[battery\|batteries]], giving them a recharge. In gas powered vehicles, the electricity can be used to power the cars electronics or sent to a battery where it can later used to give the vehicle an extra boost of power ~~- this~~ technique is currently used in some Le Mans Prototype racing cars.<ref>“Mercedes-Benz SLS Electric Drive driven full road test car review - BBC Top Gear - BBC Top Gear.” [Online]. Available: http://www.topgear.com/uk/mercedes-benz/sls/road-test/electric-drive-driven. [Accessed: 02-Dec-2013].</ref>		In electromagnetic system, the drive shaft of the vehicles is connected to an [[Electric generator\|electric generator]], which uses magnetic fields to restrict the rotation of the drive shaft, slowing the vehicle and generating electricity. In the case of electric and hybrid vehicles, the electricity generated is sent to the [[battery\|batteries]], giving them a recharge. In gas powered vehicles, the electricity can be used to power the cars electronics or sent to a battery where it can later used to give the vehicle an extra boost of power. This technique is currently used in some Le Mans Prototype racing cars.<ref>“Mercedes-Benz SLS Electric Drive driven full road test car review - BBC Top Gear - BBC Top Gear.” [Online]. Available: http://www.topgear.com/uk/mercedes-benz/sls/road-test/electric-drive-driven. [Accessed: 02-Dec-2013].</ref>

	=== Flywheel ===		=== Flywheel ===
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	=== Electromagnetic-flywheel ===		=== Electromagnetic-flywheel ===
	Electro flywheel regenerative brake is a hybrid model of electromagnetic and flywheel RBSs. It shares the basic power generation methods with the electromagnetic system; however, the energy is stored in a flywheel rather than in batteries. In this sense, the flywheel serves as a mechanical battery, where electrical energy can be stored and recovered.<ref>B. Bolund, H. Bernhoff, and M. Leijon, “Flywheel energy and power storage systems,” Renew. Sustain. Energy Rev., vol. 11, no. 2, pp. 235–258, Feb. 2007.</ref> Due to the longevity of ~~the~~ flywheel ~~battery~~ compared to lithium-ion batteries, electric flywheel RBS is the more cost effective electricity storage method. <ref>J. Li, E. Murphy, J. Winnick, and P. . Kohl, “Studies on the cycle life of commercial lithium ion batteries during rapid charge–discharge cycling,” J. Power Sources, vol. 102, no. 1–2, pp. 294–301, Dec. 2001.</ref>		Electro flywheel regenerative brake is a hybrid model of electromagnetic and flywheel RBSs. It shares the basic power generation methods with the electromagnetic system; however, the energy is stored in a flywheel rather than in batteries. In this sense, the flywheel serves as a mechanical battery, where electrical energy can be stored and recovered.<ref>B. Bolund, H. Bernhoff, and M. Leijon, “Flywheel energy and power storage systems,” Renew. Sustain. Energy Rev., vol. 11, no. 2, pp. 235–258, Feb. 2007.</ref> Due to the longevity of flywheel batteries compared to lithium-ion batteries, electric flywheel RBS is the more cost effective electricity storage method. <ref>J. Li, E. Murphy, J. Winnick, and P. . Kohl, “Studies on the cycle life of commercial lithium ion batteries during rapid charge–discharge cycling,” J. Power Sources, vol. 102, no. 1–2, pp. 294–301, Dec. 2001.</ref>

	=== Spring ===		=== Spring ===
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	Modern hybrid and electric cars both utilize an electric engine to power the car which makes applying regenerative braking very simple and efficient. In the vast majority of these cars, the transmission of the car is set up such that when the driver applies the brakes, the electric motor reverses itself and applies a resistance to the wheels rather than power. The resistance applied to the wheels is then put through the electric motor where it is used to recharge the batteries.		Modern hybrid and electric cars both utilize an electric engine to power the car which makes applying regenerative braking very simple and efficient. In the vast majority of these cars, the transmission of the car is set up such that when the driver applies the brakes, the electric motor reverses itself and applies a resistance to the wheels rather than power. The resistance applied to the wheels is then put through the electric motor where it is used to recharge the batteries.

	In high performance electric cars, improving the feel of the car is very important to car manufacturers. Many customers support electric super-cars are against purchasing them because of the lack of high performance feel. One important aspect of this feel is engine braking. In a standard internal combustion engine, once power is not being applied to the engine, the natural friction inside the engine works to slow the vehicle down. In electric cars, this friction force does not apply; however, car companies such as Mercedes and Porsche have begun to use regenerative braking systems to give the driver the same feel of a gas-powered car while recovering energy for the batteries.<ref>Mercedes-Benz SLS Electric Drive driven full road test car review - BBC Top Gear - BBC Top Gear. (n.d.). Retrieved from http://www.topgear.com/uk/mercedes-benz/sls/road-test/electric-drive-driven</ref>		In high performance electric cars, improving the feel of the car is very important to car manufacturers. Many customers support electric super-cars but are against purchasing them because of the lack of high performance feel. One important aspect of this feel is engine braking. In a standard internal combustion engine, once power is not being applied to the engine, the natural friction inside the engine works to slow the vehicle down. In electric cars, this friction force does not apply; however, car companies such as Mercedes and Porsche have begun to use regenerative braking systems to give the driver the same feel of a gas-powered car while recovering energy for the batteries.<ref>Mercedes-Benz SLS Electric Drive driven full road test car review - BBC Top Gear - BBC Top Gear. (n.d.). Retrieved from http://www.topgear.com/uk/mercedes-benz/sls/road-test/electric-drive-driven</ref>

	=== Auto Racing ===		=== Auto Racing ===

	In 2009, Formula 1 introduced a regenerative braking system called the Kinetic Energy Recovery System (KERS). The uptake of the system was slow at first and had no teams using it in the 2010 season; however, improvements to the system in the 2011 season made it extremely beneficial to cars and almost all teams adopted some form of the system. Formula one cars use either a four flywheel or electric generator system to store energy under braking. This stored energy can then be utilized by the driver by pushing a button on thier steering wheel. The FIA restricts the use to 6.67 seconds per lap during which the system gives the car an extra 81 hp.<ref>Formula 1® - The Official F1® Website. (n.d.). Retrieved from http://www.formula1.com/inside_f1/understanding_the_sport/8763.html</ref>		In 2009, Formula 1 (a common type of race car) introduced a regenerative braking system called the Kinetic Energy Recovery System (KERS). The uptake of the system was slow at first and had no teams using it in the 2010 season; however, improvements to the system in the 2011 season made it extremely beneficial to cars and almost all teams adopted some form of the system. Formula one cars use either a four flywheel or electric generator system to store energy under braking. This stored energy can then be utilized by the driver by pushing a button on thier steering wheel. The FIA restricts the use to 6.67 seconds per lap during which the system gives the car an extra 81 hp.<ref>Formula 1® - The Official F1® Website. (n.d.). Retrieved from http://www.formula1.com/inside_f1/understanding_the_sport/8763.html</ref>

	==Limitations==		==Limitations==
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	The design of RBS involves varieties of sensors and logic control units to adjust the operation of RBS. <br />		The design of RBS involves varieties of sensors and logic control units to adjust the operation of RBS. <br />
	The reliability concern of these electrical parts should not be neglected.<ref>J. Ahn, K. Jung, D. Kim, and H. Jin, “Analysis of a regenerative braking system for hybrid electric vehicles using an electro-mechanical brake,” Int. J. …, vol. 10, no. 2, pp. 229–235, 2009. </ref>		The reliability concern of these electrical parts should not be neglected.<ref>J. Ahn, K. Jung, D. Kim, and H. Jin, “Analysis of a regenerative braking system for hybrid electric vehicles using an electro-mechanical brake,” Int. J. …, vol. 10, no. 2, pp. 229–235, 2009. </ref>

			== For Further Reading ==
			For further information please see the related pages below:
			*[[Kinetic energy recovery system]]
			*[[Fuel efficiency]]
			*[[Torque]]
			*[[Drive train]] (there's a fun video explaining [[differential]]s there)
			*[[Drive shaft]]
			*Or explore a [[Special:Random\|random page]]

	==Reference==		==Reference==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-11-13T01:47:31Z

1 revision imported

← Older revision	Revision as of 01:47, 13 November 2015
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Jmdonev at 04:58, 4 October 2015

2015-10-04T04:58:46Z

← Older revision		Revision as of 04:58, 4 October 2015
Line 1:		Line 1:
	[[Category:Done 2015-03-06]] ~~[[Category: Check Images]]~~		[[Category:Done 2015-10-15]] [[Category:Automotive]]
	[[Category:Automotive]]		[[File:Flybrid_Systems_Kinetic_Energy_Recovery_System.jpg\|360px\|thumb\|right\|Figure 1. A regenerative brake.<ref>Wikimedia Commons. (October 3, 2015). ''Flybird Systems KERS'' [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/8/8e/Flybrid_Systems_Kinetic_Energy_Recovery_System.jpg</ref>]]
	[[File:~~Flywheel kers~~.jpg\|~~framed~~\|right\|~~An example of a flywheel RBS~~<ref>~~"Volvo to Test~~ KERS ~~Flywheel Tech with Grant from Swedish Government Shane McGlaun."~~ [Online]. Available:~~http~~://~~www~~.~~dailytech~~.~~com~~/~~Volvo+to+Test+KERS+Flywheel+Tech+with+Grant+from+Swedish+Government~~/~~article21776~~.~~htm~~</ref>]]		<onlyinclude>'''Regenerative braking systems''' (RBSs) are a type of [[kinetic energy recovery system]] that transfers the [[kinetic energy]] of an object in motion into [[potential energy\|potential or stored energy]] to slow the [[vehicle]] down, and increase [[fuel efficiency]].</onlyinclude><ref>M. Bodie and K. Majeed, “Regenerative braking method,” 5,707,1151998.</ref> These systems are also called kinetic energy recovery systems. There are multiple methods of energy conversion in RBSs including spring, flywheel, electromagnetic and hydraulic. More recently, an electromagnetic-flywheel hybrid RBS has emerged as well. Each type of RBS utilizes a different energy conversion or storage method, giving varying efficiency and applications for each type.

	<onlyinclude>'''Regenerative braking systems''' (RBSs) are a type of [[kinetic energy recovery system]] that transfers the [[kinetic energy]] of an object in motion into [[potential energy\|potential or stored energy]] to slow the vehicle down, and increase [[fuel efficiency]].</onlyinclude><ref>M. Bodie and K. Majeed, “Regenerative braking method,” 5,707,1151998.</ref> These systems are also called kinetic energy recovery systems. There are multiple methods of energy conversion in RBSs including spring, flywheel, electromagnetic and hydraulic. More recently, an electromagnetic-flywheel hybrid RBS has emerged as well. Each type of RBS utilizes a different energy conversion or storage method, giving varying efficiency and applications for each type.


	RBSs are installed along the [[drive train]] or fitted to the drive wheels of a vehicle where they inhibit the motion of the wheels using [[magnetic field]]s or mechanical [[torque]]. These methods of motion inhibition allow [[energy]] to be generated under braking, as opposed to [[Braking\|friction brakes]] which simply waste away energy to slow the vehicle by turning the kinetic energy into [[thermal energy]]. Due to the maximum charging rate of the energy storage mechanisms, the braking force from a RBS is limited. Therefore, a traditional friction brake system is required to maintain the safe operation of a vehicle when heavy braking is necessary. RBS can improve fuel consumption and reduce the overall braking load taken on by the vehicles friction brakes, reducing the wear on the brake pads.<ref>Robert Bosch GmbH, “Regenerative braking Active safety - Regenerative Braking Systems,” Bosch Automotive Technology. [Online]. Available: http://www.bosch-automotivetechnology.com/en/de/component/SF_PC_AS_Regenerative-Braking-Systems_SF_PC_Active-Safety_2575.html. [Accessed: 27-Oct-2013].</ref><br />		RBSs are installed along the [[drive train]] or fitted to the drive wheels of a vehicle where they inhibit the motion of the wheels using [[magnetic field]]s or mechanical [[torque]]. These methods of motion inhibition allow [[energy]] to be generated under braking, as opposed to [[Braking\|friction brakes]] which simply waste away energy to slow the vehicle by turning the kinetic energy into [[thermal energy]]. Due to the maximum charging rate of the energy storage mechanisms, the braking force from a RBS is limited. Therefore, a traditional friction brake system is required to maintain the safe operation of a vehicle when heavy braking is necessary. RBS can improve fuel consumption and reduce the overall braking load taken on by the vehicles friction brakes, reducing the wear on the brake pads.<ref>Robert Bosch GmbH, “Regenerative braking Active safety - Regenerative Braking Systems,” Bosch Automotive Technology. [Online]. Available: http://www.bosch-automotivetechnology.com/en/de/component/SF_PC_AS_Regenerative-Braking-Systems_SF_PC_Active-Safety_2575.html. [Accessed: 27-Oct-2013].</ref><br />

			RBSs are used in almost every [[electric vehicle]]s and [[hybrid electric vehicle]]s. As well, public transportation such as buses and bullet trains make use of RBSs for to decrease the environmental impacts of the transportation fleet and save money.<ref>R. Chicurel, “A compromise solution for energy recovery in vehicle braking,” Energy, vol. 24, no. 12, pp. 1029–1034, Jan. 1999.</ref>
	RBSs are used in almost every electric and hybrid electric ~~passenger vehicles~~. As well, public ~~transportations~~ such as buses and bullet trains ~~are making~~ use of RBSs for to decrease the environmental impacts of the transportation fleet.<ref>R. Chicurel, “A compromise solution for energy recovery in vehicle braking,” Energy, vol. 24, no. 12, pp. 1029–1034, Jan. 1999.</ref>


	==History==		==History==
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	The Baku-Tbilisi-Batumi railway started applying RBS in the early 1930s, this is one example of early using of this technology in railway system.<ref name=book1/>		The Baku-Tbilisi-Batumi railway started applying RBS in the early 1930s, this is one example of early using of this technology in railway system.<ref name=book1/>


	In the 1950s, Swiss company Oerlikon developed the gyrobus, which utilized flywheel as its energy storage method. The effects of [[Gyroscopic motion\|gyroscopic motion]] on the bus soon resulted in it being discontinued.<ref>J. Hampl, “Concept of the Mechanically Powered Gyrobus,” Trans. Transp. Sci., vol. 6, no. 1, pp. 27–38, Jan. 2013.</ref>		In the 1950s, Swiss company Oerlikon developed the gyrobus, which utilized flywheel as its energy storage method. The effects of [[Gyroscopic motion\|gyroscopic motion]] on the bus soon resulted in it being discontinued.<ref>J. Hampl, “Concept of the Mechanically Powered Gyrobus,” Trans. Transp. Sci., vol. 6, no. 1, pp. 27–38, Jan. 2013.</ref>


	In 1967, the American Motor Car Company (AMC) created an electrical energy regeneration brake for their concept electric car, the AMC Amitron. Toyota was the first car manufacturer to commercialize RBS technology in their Prius series hybrid cars.<ref name=book1/>		In 1967, the American Motor Car Company (AMC) created an electrical energy regeneration brake for their concept electric car, the AMC Amitron. Toyota was the first car manufacturer to commercialize RBS technology in their Prius series hybrid cars.<ref name=book1/>

	Since then, RBSs have evolved to be used in almost all electric and hybrid cars, as well as some gas-powered vehicles.		Since then, RBSs have evolved to be used in almost all electric and hybrid cars, as well as some gas-powered vehicles.


	== Methods of Energy Conversion and Storage ==		== Methods of Energy Conversion and Storage ==

J.williams: 1 revision imported

2015-08-26T21:31:35Z

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← Older revision	Revision as of 21:31, 26 August 2015
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J.williams at 16:58, 12 August 2015

2015-08-12T16:58:50Z

New page

[[Category:Done 2015-03-06]] [[Category: Check Images]]
[[Category:Automotive]]
[[File:Flywheel kers.jpg|framed|right|An example of a flywheel RBS<ref>"Volvo to Test KERS Flywheel Tech with Grant from Swedish Government Shane McGlaun." [Online]. Available:http://www.dailytech.com/Volvo+to+Test+KERS+Flywheel+Tech+with+Grant+from+Swedish+Government/article21776.htm</ref>]]

<onlyinclude>'''Regenerative braking systems''' (RBSs) are a type of [[kinetic energy recovery system]] that transfers the [[kinetic energy]] of an object in motion into [[potential energy|potential or stored energy]] to slow the vehicle down, and increase [[fuel efficiency]].</onlyinclude><ref>M. Bodie and K. Majeed, “Regenerative braking method,” 5,707,1151998.</ref> These systems are also called kinetic energy recovery systems. There are multiple methods of energy conversion in RBSs including spring, flywheel, electromagnetic and hydraulic. More recently, an electromagnetic-flywheel hybrid RBS has emerged as well. Each type of RBS utilizes a different energy conversion or storage method, giving varying efficiency and applications for each type.

RBSs are installed along the [[drive train]] or fitted to the drive wheels of a vehicle where they inhibit the motion of the wheels using [[magnetic field]]s or mechanical [[torque]]. These methods of motion inhibition allow [[energy]] to be generated under braking, as opposed to [[Braking|friction brakes]] which simply waste away energy to slow the vehicle by turning the kinetic energy into [[thermal energy]]. Due to the maximum charging rate of the energy storage mechanisms, the braking force from a RBS is limited. Therefore, a traditional friction brake system is required to maintain the safe operation of a vehicle when heavy braking is necessary. RBS can improve fuel consumption and reduce the overall braking load taken on by the vehicles friction brakes, reducing the wear on the brake pads.<ref>Robert Bosch GmbH, “Regenerative braking Active safety - Regenerative Braking Systems,” Bosch Automotive Technology. [Online]. Available: http://www.bosch-automotivetechnology.com/en/de/component/SF_PC_AS_Regenerative-Braking-Systems_SF_PC_Active-Safety_2575.html. [Accessed: 27-Oct-2013].</ref> 

RBSs are used in almost every electric and hybrid electric passenger vehicles. As well, public transportations such as buses and bullet trains are making use of RBSs for to decrease the environmental impacts of the transportation fleet.<ref>R. Chicurel, “A compromise solution for energy recovery in vehicle braking,” Energy, vol. 24, no. 12, pp. 1029–1034, Jan. 1999.</ref>

==History==
The idea of a brake that could take the kinetic energy it absorbs and turn it into potential energy for later use has been around since the late 1800s. Some of the early attempts of this technology were to install spring type RBS on front wheel drive bicycles or horse-drawn cabs.<ref>B. RIEDER, “Regenerative Braking System for Bicycles,” 2340641880.</ref><ref name=book1>W. W. Clark II and G. Cooke, Global Energy Innovation: Why America Must Lead. Praeger, 2011.</ref> 

The Baku-Tbilisi-Batumi railway started applying RBS in the early 1930s, this is one example of early using of this technology in railway system.<ref name=book1/>

In the 1950s, Swiss company Oerlikon developed the gyrobus, which utilized flywheel as its energy storage method. The effects of [[Gyroscopic motion|gyroscopic motion]] on the bus soon resulted in it being discontinued.<ref>J. Hampl, “Concept of the Mechanically Powered Gyrobus,” Trans. Transp. Sci., vol. 6, no. 1, pp. 27–38, Jan. 2013.</ref>

In 1967, the American Motor Car Company (AMC) created an electrical energy regeneration brake for their concept electric car, the AMC Amitron. Toyota was the first car manufacturer to commercialize RBS technology in their Prius series hybrid cars.<ref name=book1/>

Since then, RBSs have evolved to be used in almost all electric and hybrid cars, as well as some gas-powered vehicles.

== Methods of Energy Conversion and Storage ==
There are multiple methods of energy conversion in RBS including spring, flywheel, electromagnetic and hydraulic. More recently, an electromagnetic-flywheel hybrid RBS has emerged as well. Each type of RBS utilizes a different energy conversion or storage method, giving varying efficiency and applications for each type. Currently, the most commonly used type is the electromagnetic system.<ref>P. Clarke, T. Muneer, and K. Cullinane, “Cutting vehicle emissions with regenerative braking,” Transp. Res. Part D Transp. Environ., vol. 15, no. 3, pp. 160–167, May 2010.</ref>

=== Electromagnetic ===
In electromagnetic system, the drive shaft of the vehicles is connected to an [[Electric generator|electric generator]], which uses magnetic fields to restrict the rotation of the drive shaft, slowing the vehicle and generating electricity. In the case of electric and hybrid vehicles, the electricity generated is sent to the [[battery|batteries]], giving them a recharge. In gas powered vehicles, the electricity can be used to power the cars electronics or sent to a battery where it can later used to give the vehicle an extra boost of power - this technique is currently used in some Le Mans Prototype racing cars.<ref>“Mercedes-Benz SLS Electric Drive driven full road test car review - BBC Top Gear - BBC Top Gear.” [Online]. Available: http://www.topgear.com/uk/mercedes-benz/sls/road-test/electric-drive-driven. [Accessed: 02-Dec-2013].</ref>

=== Flywheel ===
In flywheel RBS, the system collects the kinetic energy of the vehicle to spin a [[flywheel]] that is connected to the drive shaft through a transmission and gear box. The spinning flywheel can then provide [[torque]] to the [[drive shaft]], giving the vehicle a [[power]] boost.

=== Electromagnetic-flywheel ===
Electro flywheel regenerative brake is a hybrid model of electromagnetic and flywheel RBSs. It shares the basic power generation methods with the electromagnetic system; however, the energy is stored in a flywheel rather than in batteries. In this sense, the flywheel serves as a mechanical battery, where electrical energy can be stored and recovered.<ref>B. Bolund, H. Bernhoff, and M. Leijon, “Flywheel energy and power storage systems,” Renew. Sustain. Energy Rev., vol. 11, no. 2, pp. 235–258, Feb. 2007.</ref> Due to the longevity of the flywheel battery compared to lithium-ion batteries, electric flywheel RBS is the more cost effective electricity storage method. <ref>J. Li, E. Murphy, J. Winnick, and P. . Kohl, “Studies on the cycle life of commercial lithium ion batteries during rapid charge–discharge cycling,” J. Power Sources, vol. 102, no. 1–2, pp. 294–301, Dec. 2001.</ref>

=== Spring ===
The spring loaded regenerative braking system is typically used on human powered vehicles, such as bicycles or wheelchairs. In spring RBS, a [[Spring potential energy|coil or spring]] is winded around a cone during braking to store energy in the form of elastic potential. The potential can then be returned to assist the driver while going up hill or over rough terrain.<ref>S.J.Clegg, “A review of regenerative braking systems,” Leeds, England. econ.kuleuven.be, 1996.</ref>

=== Hydraulic ===
The [[Hydraulic energy|hydraulic]] RBS slows the vehicle by generating electricity which is then used to compress a fluid. Nitrogen gas is often chosen as the working fluid. Hydraulic RBSs have the longest energy storage capability of any system, as compressed fluid does not dissipate energy over time. However, compressing gas with a pump is a slow process and severely limits the power of the hydraulic RBS.

== Applications ==
=== Hybrid and Electric Cars ===

Modern hybrid and electric cars both utilize an electric engine to power the car which makes applying regenerative braking very simple and efficient. In the vast majority of these cars, the transmission of the car is set up such that when the driver applies the brakes, the electric motor reverses itself and applies a resistance to the wheels rather than power. The resistance applied to the wheels is then put through the electric motor where it is used to recharge the batteries.

In high performance electric cars, improving the feel of the car is very important to car manufacturers. Many customers support electric super-cars are against purchasing them because of the lack of high performance feel. One important aspect of this feel is engine braking. In a standard internal combustion engine, once power is not being applied to the engine, the natural friction inside the engine works to slow the vehicle down. In electric cars, this friction force does not apply; however, car companies such as Mercedes and Porsche have begun to use regenerative braking systems to give the driver the same feel of a gas-powered car while recovering energy for the batteries.<ref>Mercedes-Benz SLS Electric Drive driven full road test car review - BBC Top Gear - BBC Top Gear. (n.d.). Retrieved from http://www.topgear.com/uk/mercedes-benz/sls/road-test/electric-drive-driven</ref>

=== Auto Racing ===

In 2009, Formula 1 introduced a regenerative braking system called the Kinetic Energy Recovery System (KERS). The uptake of the system was slow at first and had no teams using it in the 2010 season; however, improvements to the system in the 2011 season made it extremely beneficial to cars and almost all teams adopted some form of the system. Formula one cars use either a four flywheel or electric generator system to store energy under braking. This stored energy can then be utilized by the driver by pushing a button on thier steering wheel. The FIA restricts the use to 6.67 seconds per lap during which the system gives the car an extra 81 hp.<ref>Formula 1® - The Official F1® Website. (n.d.). Retrieved from http://www.formula1.com/inside_f1/understanding_the_sport/8763.html</ref>

==Limitations==
Due to the maximum recharging rate of the circuit and the capacity of battery, the braking force from an electromagnetic type RBS is always limited. Therefore, a traditional friction brake system is required to convert the excess energy from the vehicle. The friction brake can also prevent the loss of braking ability in the case of RBS failure. 

RBS can only be installed on driving wheels since a [[drive train]] is required for energy recovery. The waste heat is not significantly reduced unless the vehicle is an all wheel drive model. 

Adding a RBS to a vehicle means to increase the curb weight of it. Although RBS can improve fuel economy under start-and-stop driving conditions, it may have negative effect on fuel consumption during highway cruising.

The design of RBS involves varieties of sensors and logic control units to adjust the operation of RBS. 
The reliability concern of these electrical parts should not be neglected.<ref>J. Ahn, K. Jung, D. Kim, and H. Jin, “Analysis of a regenerative braking system for hybrid electric vehicles using an electro-mechanical brake,” Int. J. …, vol. 10, no. 2, pp. 229–235, 2009. </ref>

==Reference==
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