Cogging torque in coreless axial flux PMG (permanent magnet generator)

Click For Summary

Discussion Overview

The discussion centers around the phenomenon of cogging torque in a coreless axial flux permanent magnet generator (PMG). Participants explore the origins of this torque, the design of the generator, and the implications of its coreless structure on performance and behavior.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes significant cogging torque in their simulation of a coreless axial flux PMG and expresses uncertainty about its origin due to the absence of a stator core and slots.
  • Another participant requests a drawing of the generator design to better understand its structure.
  • A different participant suggests that the cogging torque may arise from induced currents, questioning whether there is a current path in the absence of a load and proposing a delta connection of phases as a possibility.
  • One participant shares their experience, indicating that cogging torque is not surprising and relates it to the varying magnetic alignment between the rotor and stator, comparing coreless motors to stepper motors when power is off.
  • There is a request for clarification on the types of simulations being used, specifically static and transient simulations, to aid understanding for those unfamiliar with the topic.

Areas of Agreement / Disagreement

Participants express differing views on the source of cogging torque, with some attributing it to magnetic alignment and others considering induced currents. The discussion remains unresolved regarding the exact mechanisms at play.

Contextual Notes

Participants have not fully defined the assumptions underlying their claims, and there are unresolved questions about the design specifics and simulation parameters.

akbar94
Messages
1
Reaction score
0
Poster has been reminded to post more information when asking questions at the PF.
Hi to all. I am simulating a "core less axial flux PMG". This PMG has significant cogging torque. I don't know where this torque comes from because this is a core less generator therefor there is no slot in stator ( no reluctance variation).
 
Engineering news on Phys.org
Can you post a drawing so we have an idea of the design?
 
akbar94 said:
I am simulating...

computer is quite happy to calculate anything
What have you instructed it to do ?
"Garbage in, Gospel out"

Indeed, as Tom.G asks, what does a coreless motor look like ?
akbar94 said:
no slot in stator (
Where do the stator wires go ?
 
I don't know about these devices, but it seems to me that, if there's no core, the alternative source of reaction would have to be induced currents. So is there any possible current path even when no load is attached? I have in mind maybe some sort of delta connection rather than star connection of phases.

Edit. BTW for any like me not familiar with these simulations, perhaps you could explain a little what static and transient simulations are in this context.
 
Actually I'm not too surprised by cogging torque. Likely due to the varying magnetic alignment between the rotor and stator. My experience with coreless motors is they are used when the rotational position must be stable without any applied power. Motors with a core, especially Permanent Magnet ones, have preferred positions where the rotor and stator will always settle due to the remnant magnetic field; they act almost like stepper motors with the power off.
 

Similar threads

Replies
2
Views
3K
  • · Replies 6 ·
Replies
6
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
Replies
4
Views
4K
Replies
5
Views
4K
  • · Replies 2 ·
Replies
2
Views
5K
Replies
24
Views
5K
Replies
5
Views
2K
Replies
12
Views
3K
  • · Replies 5 ·
Replies
5
Views
5K