widelto
Member
After looking up on the web and here I found no good info on Field weakening on DC motors. Has any one a link or an article with a good explanation that say more than the lower the field voltage the higher the speed.
What kind of drive is it? Any digital drive made in the past 15 or 20 years should automatically be able to set itself up for field weakening.
When using field weakening, you must have a feedback device connected on the motor. (Well, it is not absolutely necessary, and can be done unsafely without, I really advise against this).
Basically though, you will get right to 480 to 500VDC on the armature before you start weakening the field..
Hi folks:
Finally I convert my drive to field weakening.
What I learned:
- You can not use armature feedback when using field weakening, I use an optical encoder as a feedback.
- It works great with no problem and even under field weakening range speed is stable.
rdrast, I'm not sure I follow what happens under E-stop conditions as you describe.
I think what is meant is that if you have a 500V motor with a base speed of 650 rpm field weakened to say... 1300rpm; the motor is running at 2 * base speed. If you then apply full field current at 1300rpm the back EMF will rise to 2* base speed voltage, i.e. 1000V What do you think might happen if the motor were running at 2600rpm? and what do you think might happen to the control electronics?
Nick