Need some info about Brushless Motor control

[sada]

Hi
   I am new to motion control and I am planning to control a Brushless Servo Motor. What I understand from  the motion control tutorials is that I need to use a high performance controller with a third party drive to control a brushless servo motor. Can anyone let me know if thats right and also help me out in finding some more information about Brushless Servo motors and how to control its motion.

Thanks,
Sada

[Jochen]

Sada,

When you use brushless servo motors "some part" of the motion control chain has to do the electronical commutation. This can either be done by the motion control board (735x series) or by the power drive.

If the commutation is done by the motion control board you can choose a more simple type of power drive but you will have to use 2 axis outputs of your MC board to control a single motor.
The second option is more common. In this scenario the commutation is done by the drive and you need only 1 axis output to control 1 servo motor. In this scenario you may also use the mid-range boards (734x series) but of course this depends on your needs. There are a lot of vendors who provide this kind of drives. 
I by myself have worked successfully with drives for brushless motors from Kollmorgen and SEW but of course there are a lot of other good products available.

I hope that helps,

Jochen Klier
National Instruments Germany

[sada]

Hi Jochen!!
    Thanx for your reply. It has cleared some of my basic doubts about controlling a brushless motor.
Do u know where I can find some detailed information about controlling a brushless motor so that I can decide which of the two options to follow? Do I need a UMI if I follow the first option and use a simple drive? Any sort of information would be of great help to me.

Thanks!!

[Lorne H.]

Sada,

"Do u know where I can find some detailed information about controlling a brushless motor so that I can decide which of the two options to follow?"

The NI-Motion users manual has a section on brushless servo motors...

NI-Motion User Manual

The 7350 help file (the only Motion boards that can provide internal commutation) has a section on brushless servo motors.

NI 7350 User Manual

In almost everycase I am aware of, you will need to buy a UMI to interface with a brushless motor drive (the only case in which this wouldn't be true is if the Drive manufacturer created a drive specifically to cable directly to an NI Motion board).

Feel free to ask more questions,

Lorne Hengst
Application Engineer
National Instruments

[sada]

Hi Lorne!!
     Thanx for all the valuable information you have provided. It has helped me in understanding the brushless motor control more clearly.

Regards,
Sada