From the help: Tuning rule for position lag error tolerance
The position lag error tolerance is not permitted to be higher than half of one pole length!
It refer to mechanical pole length or electrical pole length?
can anyone from BRCommunity help @Swee_Hoe ?
Hello,
i don’t understand the difference between electrical and mechanical pole length. I thought there is only one pole length.
As its a safety related question i am a bit careful…
Greetings
Michael
the electrical angle always equals 180 degree. If the max limit refer to electrical way of view, it will be always 90 degree.
Hello,
-
I think the documented limit has something to do with the fact how far a motor will move if the IGBT gets defective. In this case a phase can be powered by this failure and move the motor. This movement would be dependend by the mechanical pole lenght.
-
Also the mechanical pole lenght is dependend on the motor and is not a fixed value, so they could only refer to it by its name. If the electrical pole length is a fix 180° (never heard of this - learned somethink new
) i think they would have used this fix value in documentation. -
The mechanical pole lenght is typicaly also the smaller value.
I would go with mechanical pole lenght.
Greetings
Michael
From my understanding
You have a motor with pp polepairs (that’s what B&R motors use). So you have pp*2 poles. 360° / (pp*2) will be the length of one pole and thus 360° / (pp*2) / 2 will be half of that.. The position lag refers to your mechanical postion and thus for example if you have 360 units per rev, the lag error may not exceed 360/(pp*2)/2 units to not exceed one half pole
1 Like