Back EMF & Rotor Flux: Synchronous Motor

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    Motor Synchronous
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Discussion Overview

The discussion revolves around the relationship between back electromotive force (EMF) and rotor flux in synchronous motors. Participants seek to understand the physical implications of this relationship, as well as the mechanisms involved in synchronous rotation and the effects of different magnetic fields.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about how back EMF is influenced by rotor flux, referencing the equation Ea=k*phi*w but seeking a physical explanation.
  • Another participant describes the role of three-phase field windings in producing a rotary traveling magnetic field and notes that the wound rotor has its own magnetic field, suggesting that these two fields lock to maintain synchronous rotation.
  • A participant shares links to previous threads and drawings that may provide additional context or clarification regarding synchronous generators and related concepts.
  • Another participant expresses appreciation for animations related to the topic, indicating a preference for visual aids in understanding the concepts discussed.

Areas of Agreement / Disagreement

The discussion does not appear to reach a consensus, as participants raise different aspects of the topic without resolving the initial inquiry about back EMF and rotor flux.

Contextual Notes

Participants reference various threads and resources, indicating that there may be limitations in the current discussion due to missing assumptions or dependencies on specific definitions related to back EMF and rotor flux.

Passionate Eng
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how is the back emf affected by the flux of the rotor?
I know the relation : Ea=k*phi*w
but i need a physical explanation
 
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Three phase field windings produce a rotary traveling magnetic field.
The wound rotor has a magnetic field.
The two fields lock to maintain synchronous rotation.

Which back EMF are you referring to ?
 
I made these drawings* some years ago for another thread that i can no longer find.

but you might find these two really old ones helpful
https://www.physicsforums.com/threads/synchronous-generator.538388/
https://www.physicsforums.com/threads/synchronous-generator-again.571174/
ugenetic1_zps528def0e.gif


ugenetic2_zpsb383c1b1.gif


ugenetic3_zps0b47bca3.gif


*They're hotlinked from Photobucket, an image hosting site where i placed them before PF had its "Upload" button, so the hotlink isn't inconveniencing anybody(see https://www.physicsforums.com/threads/hyperphysics-images.868337/ )

Here are two more old threads that might help
https://www.physicsforums.com/threads/armature-reaction-drop.826513/#post-5191404

see especially the animation linked in post 2 of this thread :
https://www.physicsforums.com/threa...et-alternator-under-load.754838/#post-4754007
 
Last edited:

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