Editing Linear motor (section)

== Types ==

=== Brushless ===
Brushless linear motors are members of the Synchronous motor family. They are typically used in standard [[linear stage]]s or integrated into custom, [[high performance positioning systems]]. Invented in the late 1980s by [[Anwar Chitayat]] at Anorad Corporation, now [[Rockwell Automation]], and helped improve the throughput and quality of industrial manufacturing processes.<ref>{{cite journal |author=<!--Staff writer(s); no by-line.--> |date= May 18, 1998|title=inear motors come into their own |url= https://www.designnews.com/automation-motion-control/linear-motors-come-their-own|journal= DesignNews}}</ref>

=== Brush ===
[[Brush (electric)|Brushed]] linear motors were used in industrial automation applications prior to the invention of Brushless linear motors. Compared with [[three phase]] brushless motors, which are typically being used today, brush motors operate on a single phase.<ref name=Collins>{{cite journal|last1=Collins|first1=Danielle|title=Are brushed motors suitable for industrial applications?|date=March 15, 2019|url=https://www.linearmotiontips.com/are-brushed-motors-suitable-for-industrial-applications?}}</ref> Brush linear motors have a lower cost since they do not need moving cables or three phase servo drives. However, they require higher maintenance since their brushes wear out.

=== Synchronous ===
In this design the rate of movement of the magnetic field is controlled, usually electronically, to track the motion of the rotor. For cost reasons synchronous linear motors rarely use [[Commutator (electric)|commutators]], so the rotor often contains permanent magnets, or [[Magnetic core#Soft iron|soft iron]]. Examples include [[coilgun]]s and the motors used on some [[maglev]] systems, as well as many other linear motors. In high precision industrial automation linear motors are typically configured with a magnet stator and a moving coil. A  [[Hall effect sensor]] is attached to the rotor to track the [[magnetic flux]] of the stator. The electric current is typically provided from a stationary [[servo drive]] to the moving coil by a moving cable inside a [[cable carrier]].

=== Induction ===
[[File:Three phase linear induction motor.gif|thumb|A typical 3 phase linear induction motor. An aluminium plate on top often forms the secondary "rotor".]]
{{main|Linear induction motor}}
In this design, the force is produced by a moving linear [[magnetic field]] acting on conductors in the field. Any conductor, be it a loop, a coil or simply a piece of plate metal, that is placed in this field will have [[eddy current]]s [[electromagnetic induction|induced]] in it thus creating an opposing magnetic field, in accordance with [[Lenz's law]].<ref name=Liasi>{{cite journal|last1=Ghaseminejad Liasi|first1=Sahand|title=What are linear motors?|date=15 May 2015|pages=1–50|doi=10.13140/RG.2.2.16250.18887|url=https://www.researchgate.net/publication/322040360|access-date=24 December 2017}}</ref> The two opposing fields will repel each other, thus creating motion as the magnetic field sweeps through the metal.
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=== Homopolar ===
[[File:Railgun-1.svg|thumb|Railgun schematic]]
{{main|Railgun}}
In this design a large current is passed through a metal sabot across sliding contacts that are fed by two rails. The magnetic field this generates causes the metal to be projected along the rails.

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=== Tubular ===
{{main|Tubular linear motor}}
Efficient and compact design applicable to the replacement of [[pneumatic cylinder]]s.

=== Piezoelectric ===
[[File:Piezomotor type inchworm.gif|thumb|right|Piezoelectric motor action]]
{{main|Piezoelectric motor#Stepping actions}}
[[Piezoelectricity|Piezoelectric]] drive is often used to drive small linear motors.
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