Home     Contact     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science     RSS     Terms of services     Privacy policy  
   
 Home     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science   

Author Topic: How to calculate the brush position for a DC motor  (Read 2089 times)

0 Members and 1 Guest are viewing this topic.

Spatial

  • Newbie
  • *
  • Posts: 3
How to calculate the brush position for a DC motor
« on: October 13, 2014, 03:29:22 AM »
When I look at a brush holder from above I can see that the brushes are set at different angles. I assume this has to do with the diameter of the commutator, degrees between slots, number of slots and brush width?

Is there a formula that calculates the optimum brush position using these parameters?

I am looking at a brush holder on a DC PM with four brushes and a commutator with 29 slots (starter motor) I can see the offset is 20 degrees at the commutator face but wonder how this was arrived at?

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: How to calculate the brush position for a DC motor
« Reply #1 on: October 13, 2014, 08:45:21 AM »
i try to get the image but i cannot. what do you mean 20 degrees at the face? do you have a picture to indicate this?

Spatial

  • Newbie
  • *
  • Posts: 3
Re: How to calculate the brush position for a DC motor
« Reply #2 on: October 13, 2014, 08:52:22 AM »
I have circled the area I am referring to.  We want to have this motor CCW currently its CW.  When we simple swap the poles we see a drop of 50% in the torque which we do not expect and are wondering if the brushes need to be adjusted on the brush holder but everything I have read says this should not be necessary?
Thanks!

kam

  • Administrator
  • Hero Member
  • *****
  • Posts: 1849
Re: How to calculate the brush position for a DC motor
« Reply #3 on: October 13, 2014, 09:01:56 AM »
You talk about 4 brushes, but i cannot see them in this drawing. Note the actual brush position with a green color to see. Also, how many windings are on the motor? 3? Do you have a motor picture?

Spatial

  • Newbie
  • *
  • Posts: 3
Re: How to calculate the brush position for a DC motor
« Reply #4 on: October 13, 2014, 09:06:21 AM »
Attached is a 3D of the brushes, my interest is in knowing how you determine the correct orientation of these brushes?

Sorry I tried pasting it here but I must be doing something wrong?




« Last Edit: October 13, 2014, 10:19:25 AM by Spatial »