Urgent Help on Brushless DC Drive

Always not enough information.

What are the model numbers of the drive, the motor, and the PLC you are interfacing with?

Have you RTFMs*?

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*RTFM

Gash. I wish I have the RTFMs...... but unfortunately no..... The motor is rated for 640 DC and continuous duty with running RMS AMPS of 149. It is driven by a drive that accepts TORQUE command which is where I am stuck. We are planning to interface to OMRON or SIEMENS PLC based on who gives better offer.

Found this, don't know if it applies...

http://www.clusterresources.com/torquedocs/

Thanks for this URL, but unfortunately this downloads documentation only for new motors whereas the motor I have belong to 1997 range. It's Brushless DC 75 HP rated for maximum 640 V DC with peak current of 400 AMPS.

Thanks for some discrete information that you provided. Let me check and revert. Now, why do you say not to worry about MOTOR DIRECTION signal point?

And, OBW the drive does not specifically have any FOR / REV input point. I guess MOTOR DIRECTION input point is the one which commands motor to rotate in CW or CCW direction.

I said not worry about motor direction input because it is the easiest to figure.

And you seem to have found the rotation select input, every manufacturer names it in diferent ways; it can be a two point set of inputs i.e. FWD and REV or CW and CCW, it can be a single input i.e. CW/CCW, FW/REV or can be a bypolar analog input, in which the polarity of the command signal determines the rotation, but this last one is not your application, since you said that the speed signal is simple 0 to 10VDC.

Does your application require rotation reversing or not ?

Regards

Basically, I did some analysis of inputs you mentioned but they are different. First of all, there is no separate source that they use to regulate either torque or speed command. The speed command problem was solved by connecting an external 10V source through 5K POT and it seemed to work well. But, the TORQUE COMMAND & MOTOR COMMAND terminals that exist on motor show +15V DC when NOT connected. Looks like the existing but FAULTY PLC takes this input and "sinks" it at a frequency that defines motor torque. Unable to comprehend. All I want to know is HOW the motor torque can be controlled IF THIS INPUT DOES NOT EXIST.

Some manufacturers use an inverse system - is there a ground or zero volt terminal to use as the common 'low'? The wiring would appear just as drawing above, but the current would be flowing in the opposite direction.

Some also use a "centre zero" on speed control, so 5V would give no rotation, zero would turn one way, and 10V the other.

even with the help of speed you can control the motor . a single encoder with the feeder CT we can control the speed of the motor .

75 HP is a high rating for BLDC.It will be better to contact the manufacturer and take his help

I wish I had the support from manufacturer but unfortunately it's a big NO. They have stopped manufacturing these drives long back and hence does not seem to know anything of it. Or, I would say they may have some data in their archives but are not willing to part with it. Motor was manufactured in 1997. So.....