Kommutator (elektrisk): Forskelle mellem versioner
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{{Harflertydig|Kommutator}}
[[File:Kommutator universalmotor stab.jpg|thumb|En elektromotor fra en [[støvsuger]]. Kommutatoren ses til venstre.]]
En mekanisk '''kommutator''' er en vinkelafhængig [[elektrisk omskifter]], som sidder på [[rotor]]en af [[elektromotor]]er til [[jævnspænding]] og som formidler den elektriske kontakt via fjederbelastet kul eller metal, som sidder på statoren. Kommutatoren fungerer som en variabel frekvens [[vekselretter]].<ref>[https://www.sciencedirect.com/topics/engineering/commutator Fundamental Concepts: Motors: Commutator] Citat: "...The commutator on the DC generator converts the AC into pulsating DC...By mechanically positioning the brushes on the commutator, an angle of displacement can be set up between the magnetic force of the field windings and the magnetic force of the rotor windings...", [https://web.archive.org/web/20210909192100/https://www.sciencedirect.com/topics/engineering/commutator backup]</ref><ref>
En del nyere elektromotorer har [[elektronisk kommutering]] de kaldes fx [[Børsteløs DC-motor|Børsteløse DC-motorer]]. Fordelen ved disse elmotorer er mindre mindre vedligeholdelse, højere mulig start [[drejningsmoment]], variabel hastighed, lavere udgift og mindre [[elektrisk støj]].<ref>[http://www.industrial-electronics.com/emct_2e_7f.html industrial-electronics.com: The non-classic motors: Electronic commutation for the DC brushless motor] Citat: "... In a way, this machine can be viewed as a dc motor in which electronic commutation replaces the commutator and brushes. The mere fact that the commutator-brush assemblage is dispensed with, implies low maintenance, low RFI and EMI, and low cost...For example, such features as high starting torque and variable speed can now easily be realized together..."</ref><ref>[https://www.sciencedirect.com/science/article/abs/pii/S0142061512000695 sciencedirect.com: Electronic Commutator Direct Current (ECDC) machine] Citat: "...Today new technology is attempting to replace these components and reduce permanently these maintenance costs. When the task of commutator and brushes are replaced by solid-state switches, free maintenance motors are invented and the new motor called brushless DC motors emerged..."</ref> Elektronisk kommutering kan fx anvende [[Hall sensor]]er, som registrerer magnetfeltsveksling og de anvendes til at styre [[transistor]]er eller andre [[halvleder]]komponenter.<ref>[http://fab.cba.mit.edu/classes/961.04/topics/brushless_DC1.pdf July 2000, fab.cba.mit.edu: Electronic commutation] Citat: "...The stator, on the other hand, consists of a three-phase, Y-connected winding and three Hall-effect sensors. The sensor magnet turns the Hall-effect sensors “on” and “off,” indicating the position of the shaft. With this information, the controller is able to switch current to each winding at the optimum timing point...", [https://web.archive.org/web/20210824193203/http://fab.cba.mit.edu/classes/961.04/topics/brushless_DC1.pdf backup]</ref>
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