Editing Electric motor (section)

==Types==
Electric motors operate on one of three physical principles: [[magnetism]], [[Electrostatic motor|electrostatics]] and [[Piezoelectric motor|piezoelectricity]].

In magnetic motors, magnetic fields are formed in both the rotor and the stator. The product between these two fields gives rise to a force and thus a torque on the motor shaft. One or both of these fields changes as the rotor turns. This is done by switching the poles on and off at the right time, or varying the strength of the pole.

Motors can be designed to operate on DC current, on AC current, or some types can work on either. 

AC motors can be either asynchronous or synchronous.<ref>{{Cite book|last=Kim|first=Sang-Hoon|url={{google books |plainurl=y |id=ewKqDQAAQBAJ|page=6}}|title=Electric Motor Control: DC, AC, and BLDC Motors|publisher=Elsevier|year=2017|isbn=97-80128123195|language=en}}</ref> Synchronous motors require the rotor to turn at the same speed as the stator's rotating field. Asynchronous rotors relax this constraint.

A [[fractional-horsepower motor]] either has a rating below about 1 horsepower (0.746&nbsp;kW), or is manufactured with a frame size smaller than a standard 1 HP motor. Many household and industrial motors are in the fractional-horsepower class.
{| class="wikitable"
|+Type of motor commutation<ref>{{Cite web|title=Electric motor classification|url=https://en.engineering-solutions.ru/motorcontrol/motor/#classification|access-date=2021-05-31|website=en.engineering-solutions.ru}}</ref><ref name="USDOEVSPGuide2">{{cite web|date=May 2004|title=Variable Speed Pumping, A Guide to Successful Applications, Executive Summary|url=http://www1.eere.energy.gov/industry/bestpractices/pdfs/variable_speed_pumping.pdf|archive-url=https://web.archive.org/web/20111027042737/http://www1.eere.energy.gov/industry/bestpractices/pdfs/variable_speed_pumping.pdf|archive-date=October 27, 2011|access-date=February 19, 2018|publisher=USDOE – Europump – Hydraulic Institute|page=9, Fig. ES–7}}</ref>{{sfn|Bose|2006|pp=328, 397, 481}}<ref name="King (UA)2">{{cite conference|last=Knight|first=Andy|title=Electric Machines|url=http://www.ece.ualberta.ca/~knight/electrical_machines/fundamentals/f_main.html|publisher=U. of Alberta|archive-url=https://web.archive.org/web/20130718235942/http://www.ece.ualberta.ca/~knight/electrical_machines/fundamentals/f_main.html|archive-date=18 July 2013|access-date=20 February 2013}}</ref>{{sfn|Hameyer|2001}}<ref name="Stolting (2008)2">{{cite book|title=§1.3.1.1 Motor Systematics in Chapter 1 – Introduction|page=5, Table 1.1}} in {{harvnb|Stölting|Kallenbach|Amrhein|2008|p=5}}</ref><ref name="Ionel (2010)2">{{cite conference|last=Ionel|first=D.M.|year=2010|title=High-Efficiency Variable-Speed Electric Motor Drive Technologies for Energy Savings in the US Residential Sector|publisher=IEEE|pages=1403–14|doi=10.1109/OPTIM.2010.5510481|isbn=978-1-4244-7019-8 |book-title=12th International Conference on Optimization of Electrical and Electronic Equipment (OPTIM)}}</ref>
! colspan="3" |Self-commutated
! colspan="2" |Externally commutated
|-
! colspan="2" |Mechanical commutator
!Electronic commutator<ref name="Ionel (2010)2" />{{efn|The term 'electronic commutator motor' (ECM) is identified with the heating, ventilation and air-conditioning (HVAC) industry, the distinction between BLDC and BLAC being in this context seen as a function of degree of ECM drive complexity with BLDC drives typically being with simple single-phase [[scalar (mathematics)|scalar-controlled]] voltage-regulated trapezoidal current waveform output involving surface PM motor construction and BLAC drives tending towards more complex three-phase [[vector control (motor)|vector-controlled]] current-regulated sinusoidal waveform involving interior PM motor construction.<ref name="Ionel (2010)">{{cite conference|book-title=12th International Conference on Optimization of Electrical and Electronic Equipment (OPTIM)|title=High-Efficiency Variable-Speed Electric Motor Drive Technologies for Energy Savings in the US Residential Sector |last=Ionel|publisher=IEEE|first=D.M.|year=2010|doi=10.1109/OPTIM.2010.5510481|pages=1403–14|isbn=978-1-4244-7019-8 }}</ref>}}
!Asynchronous
!Synchronous[[Electric motor#CharacterizatioNote2|<sup>2</sup>]]
|-
!AC<ref name="Alger (1949b)2">{{cite book|last=Alger|first=Philip L.|title=§274–§287 'AC Commutator Motors' sub-section of Sec. 7 – Alternating-Current Generators and Motors|pages=755–63|display-authors=etal}} in {{harvnb|Knowlton|1949}}</ref>{{efn|The universal and repulsion motors are part of a class of motors known as AC commutator motors, which also includes the following now largely obsolete motor types: Single-phase – straight and compensated series motors, railway motor; three-phase – various repulsion motor types, brush-shifting series motor, brush-shifting polyphase shunt or Schrage motor, Fynn-Weichsel motor.<ref name="Alger (1949b)">{{cite book|title=§274–§287 'AC Commutator Motors' sub-section of Sec. 7 – Alternating-Current Generators and Motors|first=Philip L.|last=Alger|pages=755–63|display-authors=etal}} in {{harvnb|Knowlton|1949}}</ref>}}
![[Brushed DC electric motor|DC]]
!AC[[Electric motor#CharacterizatioNote5|<sup>5</sup>]]<sup>, [[Electric motor#CharacterizatioNote6|6]]</sup>
! colspan="2" |AC[[Electric motor#CharacSterizatioNote6|<sup>6</sup>]]
|-
|
* [[Universal motor|Universal]] (AC commutator series<ref name="Stolting (2008)2" /> or AC/DC{{sfn|Hameyer|2001}})[[Electric motor#CharacterizatioNote1|<sup>1</sup>]]
* [[Repulsion motor|Repulsion]]
|Electrically
excited:

* Separately excited
* Series
* Shunt
* Compound

PM
|PM rotor:

* [[Brushless DC motor|BLDC]]

Ferromagnetic rotor:

* [[Switched reluctance motor|SRM]]
|Three-phase:

* [[Induction motor|SCIM]] [[Electric motor#CharacterizatioNote3|<sup>3</sup>]]<sup>, [[Electric motor#CharacterizatioNote8|8]]</sup>
* [[Wound rotor motor|WRIM]] [[Electric motor#CharacterizatioNote4|<sup>4</sup>]]<sup>, [[Electric motor#CharacterizatioNote7|7]], [[Electric motor#CharacterizatioNote8|8]]</sup>

Two-phase

(condenser)

Single-phase:

* Auxiliary winding (split-phase: resistance or capacitor start)
* [[Shaded-pole motor|Shaded-pole]]
* Asymmetrical stator
|[[Synchronous motor|WRSM]], [[Permanent magnet synchronous motor|PMSM]] or BLAC:<ref name="Ionel (2010)2" />

* IPMSM
* SPMSM

[[Reluctance motor|SyRM]]

Hysteresis

Hybrid:

* SyRM-PM hybrid
* Hysteresis-reluctance

[[Stepper motor|Stepper]]
|-
|Simple electronics
|Rectifier,
linear transistor(s)
or DC chopper
|More elaborate
electronics
| colspan="2" |Most elaborate
electronics ([[Variable-frequency drive|VFD]]), when provided
|}
Notes:

1. <span id="CharacterizatioNote1">Rotation is independent of the frequency of the AC voltage.</span>

2. <span id="CharacterizatioNote2">Rotation is equal to synchronous speed (motor-stator-field speed).</span>

3. <span id="CharacterizatioNote3">In SCIM, fixed-speed operation rotation is equal to synchronous speed, less slip speed.</span>

4. <span id="CharacterizatioNote4">In non-slip [[Energy recovery|energy-recovery]] systems, WRIM is usually used for motor-starting but can be used to vary load speed.</span>

5. <span id="CharacterizatioNote5">Variable-speed operation.</span>

6. <span id="CharacterizatioNote6">Whereas induction- and synchronous-motor drives are typically with either six-step or sinusoidal-waveform output, BLDC-motor drives are usually with trapezoidal-current waveform; the behavior of both sinusoidal and trapezoidal PM machines is, however, identical in terms of their fundamental aspects.<ref name="Krishnan (2008)2">{{cite book|last=Krishnan|first=R.|url={{google books |plainurl=y |id=U-RxikH3aXEC|page=378}}|title=Permanent Magnet Synchronous and Brushless DC Motor Drives|publisher=CRC|year=2008|isbn=978-0-8247-5384-9|page=xvii|archive-url=https://web.archive.org/web/20180104232727/https://books.google.com/books?id=U-RxikH3aXEC&pg=PA378&lpg=PA378&dq=Ionel,+D.M&source=bl&ots=3dMK2uR8Nx&sig=NN3mUqDsWms5wXNVMc7bQjjxFZE&hl=en&sa=X&ei=o2QyUdSJN-jXiAL7q4G4Cg&ved=0CDsQ6AEwAzgK|archive-date=2018-01-04|url-status=live}}</ref></span>

7. <span id="CharacterizatioNote7">In variable-speed operation, WRIM is used in slip-energy recovery and double-fed induction-machine applications.</span>

8. <span id="CharacterizatioNote8">A cage winding is a short-circuited squirrel-cage rotor, a wound winding is connected externally through slip rings.</span>

9. <span id="CharacterizatioNote9">Mostly single-phase with some three-phase.</span>

Abbreviations:

* BLAC – [[Brushless AC electric motor|Brushless AC]]
* BLDC – [[Brushless DC electric motor|Brushless DC]]
* BLDM – Brushless DC motor
* EC – Electronic commutator
* PM – [[Permanent magnet]]
* IPMSM – Interior permanent-magnet synchronous motor
* PMSM – [[Permanent magnet synchronous motor]]
* SPMSM – Surface permanent magnet synchronous motor
* SCIM – [[Squirrel-cage rotor|Squirrel-cage]] [[induction motor]]
* SRM – [[Switched reluctance motor]]
* SyRM – [[Reluctance motor|Synchronous reluctance motor]]
* VFD – [[Variable-frequency drive]]
* WRIM – [[Wound rotor motor|Wound-rotor induction motor]]
* WRSM – [[Synchronous motor|Wound-rotor synchronous motor]]
* {{Anchor|LRA}}LRA – Locked-rotor amps: The current you can expect under starting conditions when you apply full voltage. It occurs instantly during start-up.
* RLA – Rated-load amps: The maximum current a motor should draw under any operating conditions. Often mistakenly called running-load amps, which leads people to believe, incorrectly, that the motor should always pull these amps.
* FLA – Full-load amps: Changed in 1976 to "RLA – rated-load amps".