Old servo to new drive

[Dave3891]

I have a NSK motor / drive system that the drive is gone on and new NSK drives are not made anymore.

I want to hook the motor to a newer servo drive but I am not sure about the phase wiring.

The motor is a NSK megatorque. One of the problems with the motor is that it uses a non standard resolver for feed back, so I am planning on mounting a encoder to the motor for feedback to the drive.
The motor is 3 phase AC, but each phase has a + and - connection (A+,A-,B+,B-,C+,C-) and most new drives only have just A,B,C connections.
So I wanted to know how I can hook this up to a newer drive such as a AMC B30A40AC or any other suggested drive.

I am attaching a few pages from the NSK manual for specs on the motor.

Thanks
Dave

[Al_The_Man]

You do not mention what CNC control you are using?
The drive you show in the link appears to be AC sinusoidal and the AMC is BLDC, you would have to fit an encoder that has commutation pulses and align it to the motor phases, I have shown how to do this in previous links.
Most BLDC and many AC servo's are connected in delta internally, so you would have to connect the three windings in delta with the + of one winding going to the - of the next in turn to achieve a delta connection.
Al.

[Dave3891]

The control is a old DOS pc program running a galil card with +-10v signal to the drive. And the galil needs to see the encoder as well.

Do you have any recomendations for a drive that would work better the the AMC?

Thanks
Dave

[Al_The_Man]

Out of interest, what is the DOS program called, I use Galil and A-M-C all the time, use torque mode.
You do not need to take the encoder back to the drive.
Al.

[Dave3891]

The program is custom made by Quickmill. It was written in basic and they included the source with the machine.
It is old but very reliable, I have done a motherboard upgrade to the machine since it was origionaly a 386 with a orange mono screen.
I got a industrial P4 board with a ISA slot to run the galil card and everything works well.
If you want any more info on the software just PM me.

If I use a AMC drive and don't bring the encoder to the drive, will I still have to phase align the encoder to the motor?

Thanks
Dave

[Al_The_Man]

I would be very interested in a copy of the s/w. I can PM you an email.
I would guess it is running a DMC-1000 series card?
You will still have to align the encoder to the rotor, you also need to know how many poles on the motor for ordering the correct encoder.
You can put a 'scope on one of the phases and turn the shaft and see how many cycles/rev.
Al.

[Dave3891]

I have a scope so that should not be a problem to measure. Do you put any low voltage on the phases? Or can you get a good reading just by spinning it with only the probe hooked up?

Can you recomend a good encoder with the phase pulses?


Thanks
Dave

[Al_The_Man]

The scope alone will tell you across one of the phases, the amount of positive peaks of the sine wave is the amount of poles x2.
It most likely is an 8 or 6 pole motor.
I have mostly used Renco encoders, when ordering the encoder resolution followed by the pole count/2, for e.g. a 2000/4 would be for an 8 pole motor.
They have since been taken over by Heidenhain so there are not many deals there anymore.
Is the card number a DMC-1000 do you know?
Al.

[Dave3891]

It is either a DMC-1000 or DMC-1500 I can't remember. It is a 4 axis ISA.

So if I get a encoder with the right phases and a AMC drive, I should be able to drive the motor?
Any other problems that I might run into?

Thanks
Dave.

[Al_The_Man]

I haven't converted that particular motor, I have put Renco's on Fanuc Redcap servo's and turned them into BLDC for Galil operation.
You will also have to change the encoder count configuration in the s/w.
If you can use a through hole type it may be easier to mount.
If using a ISA slot then it will be a 1000, the 1500 is a stand-alone unit.
Al.

[Dave3891]

I found the motor details in the manual, I have attached the pages for the information.

It says it is a 18 pole motor with each phase having 6 poles.

[Al_The_Man]

That is a very specialized motor, and no, you won't be able to drive it with a A-M-C or similar BLDC, you may have a problem finding a drive other than finding an exact replacement somewhere.
Worse case scenario will be to replace motor and drive!.
Would it be the same as ebay 160675112973?
Al.