AC Servo Drives - Driving me nuts!

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ashesman
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Re: AC Servo Drives - Driving me nuts!

Post by ashesman »

On a side note, is https://www.precision-elec.com/ legitimate? Always hard to tell when buying stuff from the opposite side if the world!
ashesman
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Re: AC Servo Drives - Driving me nuts!

Post by ashesman »

I have had some progress on this... I ordered a Hitachi drive from hitachiacdrive.com. They took my money, said on the phone they had one in stock and could ship immediately. Now each time I call they promise to email me an update or tracking number then nothing comes. Its starting to feel like I have been scammed, but will have to wait a little longer to see!

Anybody in the USA dealt with this company? HitachiDrive.com (powered by AutomatedPT). Apparently located at 808 Industrial Boulevard Colleyville, TX 76034.

In the mean time I got an encoder card for the ABB ACS355 drive I have. It kind of works. Low RPM speed is stable but it is impossible to tune it to get good torque response at low speed without it getting an over current error on large speed steps. It would do if you just wanted a constant RPM control of an AC servo motor where there were no sudden speed changes or load increase was not sudden.
ashesman
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Re: AC Servo Drives - Driving me nuts!

Post by ashesman »

slodat wrote: Tue Apr 13, 2021 5:08 pm Have you looked at Yaskawa spindle motors? I know they are not cheap, but used ones are plentiful and they have the kind of characteristics you are looking for. I'm powering the one that came in my mill with a Hitachi SJ-P1 drive and it's working well.
SJ-P1 drive arrived finally yesterday with encoder interface. Unfortunately it is much to big for the gap I have on my control panel but if it works I will find a way to make it fit! I have done all the tests to get the the motor constants, just need some time to wire it up and test it. Watch this space to see how it goes...
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Re: AC Servo Drives - Driving me nuts!

Post by ashesman »

Ok, so I hooked up the SJ-P1 and set all my motor data and it just went. Still not tuned quite right yet but a good start. It does have a few issues to solve. It faults if I go over 240 hz which I cant quite find the setting to allow it to go higher yet. The drive can do 600Hz so it will be there somewhere... there is also a scary thing where if you stall the motor at low speed then let it go, it starts turning slow and goes to 26 Amps which is really bad and a good way to toast a PMMs magnets.

It is also going to need a braking resistor as it faults if you try to decelerate it too fast. I will order one.

But finally a win after four months of trying drives and research.
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Re: AC Servo Drives - Driving me nuts!

Post by slodat »

I have found Hitachi’s tech support folks to be really helpful.
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Re: AC Servo Drives - Driving me nuts!

Post by ashesman »

slodat wrote: Fri May 07, 2021 6:46 am I have found Hitachi’s tech support folks to be really helpful.
Yes, I was thinking a call to them regarding the super high current at stall would be a good idea. I was pretty late when I rushed setting it up last night. I will go over everything today and have another play.

What is the best way to contact them?
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Re: AC Servo Drives - Driving me nuts!

Post by ashesman »

Just for anyone who reads through this post and is thinking about using a SJ-P1 on a permanent magnet motor...

A note that an SJ-P1 cannot do closed loop vector control on a permanent magnet motor. Confirmed by Hitachi technicians. All it can use the encoder for is measuring actual motor speed. I ended up taking my encoder adapter off as it is no use to me now! It can use it on induction motors though.
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