Wikicars - User contributions [en]

Regenerative braking

2007-05-04T15:11:53Z

62.87.120.166: /* See also */

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: 
* 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. 

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. 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>[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 ==

* [[Electromagnetic brake]]
* [[Dynamic braking]]

==References==
<references />

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

Regenerative braking

2007-05-04T15:11:35Z

62.87.120.166: /* References */

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: 
* 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. 

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. 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>[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 ==

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

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

Regenerative braking

2007-05-04T15:11:19Z

62.87.120.166: /* References */

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: 
* 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. 

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. 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>[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 ==

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

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

Regenerative braking

2007-05-04T15:11:08Z

62.87.120.166: /* Use in motor sport */

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: 
* 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. 

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. 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>[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 ==

* [[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]]

Regenerative braking

2007-05-04T15:09:41Z

62.87.120.166:

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: 
* 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. 

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. 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]]

Mild hybrid

2007-05-04T15:09:07Z

62.87.120.166:

'''Mild hybrids''' are essentially conventional vehicles with oversized starter motors, allowing the engine to be turned off whenever the car is coasting, braking, or stopped, yet restart quickly and cleanly. Accessories can continue to run on electrical power while the engine is off, and as in other hybrid designs, the motor may be used for [[regenerative braking]] to recover energy. The larger motor is used to spin the engine up to operating rpm speeds before injecting any fuel.

Many people do not consider these to be hybrids at all since they do not have hybrid drivetrains (there is no electric motor to drive the vehicle), and these vehicles do not achieve the fuel economy of full hybrid models. A major example is the 2005 [[Chevrolet Silverado Hybrid]], a full-size [[pickup truck]]. Chevrolet was able to get a 10% improvement on the Silverado's fuel efficiency by shutting down and restarting the engine on demand. Mild hybrids often use 48 volt systems to supply the power needed for the startup motor, as well as to compensate for the increasing number of electronic accessories on modern vehicles.

Compared to a "full" hybrid vehicle, however, mild hybrids may provide many of the benefits of the application of hybrid technologies, with less of the cost/weight penalty that is incurred by installing the parallel (electric) hybrid drivetrain. Fuel savings would generally be lower than expected with use of a full hybrid design.

[[General Motors Corporation|General Motors]] followed the pickup truck hybrid with their [[Belt alternator starter]] (BAS) hybrid system, used in the [[2006]] [[Saturn VUE|Saturn VUE Green Line]]. It operates in much the same manner as the "start-stop" system in the Silverado, but the electric motor can also provide modest assist under acceleration.

[[Category:Hybrid vehicles]]