Help with servo motor


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  1. #1
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    Default Help with servo motor

    I have this servo motor on pictures and I need help to see is sevo motor good or bad.
    I read on internet how to check an servo motor with multimeter.
    I measure the resistance between 1-2, 1-3, 2-3 and show 1,8 ohm is this ok, no values to ground.
    Is this servo for spindle head or can I use for moving xyz table
    What servo drive do you recommend for this servo motor

    See pictures for questions

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    Default Re: Help with servo motor

    Hi,
    the unit on the end of the shaft is a resolver. Its a very clever analogue encoder. Old school stuff but very rugged and reliable.

    You require a servo drive that can accommodate a resolver.....and there are resolvers and resolvers. Is it a two pole or a four pole or an eight pole resolver
    for instance?

    I think that trying to find a suitable drive is going to be a nightmare.

    I have a large (2.65kW 12Nm) servo with a resolver I bought for a spindle motor. I couldn't find a drive to match the eight pole
    resolver so I decided to make one. It is a big ask....I wouldn't recommend it.

    Another possibility is to swap the resolver for an encoder, that would increase the range of servo drives that could be used.

    If you want reliable use without problems buy a matching servo and drive.

    I bought a second hand 1.8kW Allen Bradley servo and matching drive for $600. I had to buy cables and the software to set it up but its
    been a superb spindle motor for me.

    You might want to try a sensorless vector drive VFD. Then you wouldn't have to use or worry about the resolver. I tried and it does work for
    a spindle but not as well as I hoped....ergo my decsion to build a drive.

    Craig



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    Default Re: Help with servo motor

    Hi,
    the two small blue wires are for a thermal switch.

    The speed is 157 radians per second (157 / 2 / 3.141) X 60 =1500 rpm.
    The torque figure must be an instaneous overload value, not continuous.

    Continuos torque= 2kW/157 =12.7 Nm

    Craig



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    Default Re: Help with servo motor

    Hi,
    maybe I'm misreading the pic, the way its layed out suggests that the continuous torque is 22Nm ands
    its overload is 60Nm. That makes it a powerful servo.

    Craig



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    Community Moderator Al_The_Man's Avatar
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    Default Re: Help with servo motor

    What I have done in the past to this kind of motor is to remove the resolver and fit a through hole quadrature encoder version with commutation tracks and turn it into a BLDC motor, you need to align the encoder with a double beam 'scope however..
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Default Re: Help with servo motor

    How to I know is it two pole or a four pole or an eight pole resolver.



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    Default Re: Help with servo motor

    Hi,
    there maybe some indication in the manufacturers markings.

    Other than that you will have to measure it. That will in turn require a signal generator capable of 5kHz sinusoid and a dual trace scope.
    How's your electronics skills?

    My servo is an eight pole motor and has been fitted with an eight pole resolver. It is not uncommon however for a four or eight pole motor
    to be fitted with a two pole resolver.

    The only manufacturer I know of that produces resolver ready drives is ABB. ABB own Baldor, a US manufacturer of motors and servos including resolver
    equipped servo motors. A 10A ABB servo drive will cost an ABSOLUTE FORTUNE. I really like ABB gear, its beautifully made and engineered but its just
    TOO EXPENSIVE........I don't want to encourage them by paying their prices.

    Craig



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    Default Re: Help with servo motor

    Hi,
    I can understand wanting to reuse what looks to be a powerful servo. In this case however I suspect the cost of a drive, if you can find a suitable one
    is likely to be high, so much so that your dream of a cheap yet powerful spindle motor will evaporate.

    You could try using a vector capable VFD. They work OK as a spindle motor but don't have positioning capability so you couldn't use one as a servo.
    I found the response of a permanent magnet servo motor with a vector drive to be less than I hoped. It is however a cheap alternative.

    The last possibility is to as Al has suggested fit an encoder and then supply a matching drive. That is perfectly doable but unless you have some pretty good
    skills you could end up with no result. Al has many years experience....whether you or I could do what he has is debatable.

    Just as a comparison I have linked to a 1.8kW DMM servo and matching drive. DMM is a Canadian company that manufacture in China. They have carved out
    a good reputation for quality at very attractive prices. They are by no means the only company competing in this market segment but is representative of what is
    out there.
    https://store.dmm-tech.com/products/...ac-servo-motor
    https://store.dmm-tech.com/products/...nt=20981907526
    $645 for a 1.8kW servo and matching driveis pretty good value. Note you would need cables as well, they aren't included.

    Craig



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    Community Moderator Al_The_Man's Avatar
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    Default Re: Help with servo motor

    Quote Originally Posted by toneV8 View Post
    How to I know is it two pole or a four pole or an eight pole resolver.
    You short the stator wires and rotate the armature shaft 1 revolution and count the 'bumps' this is the No. of poles.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Default Re: Help with servo motor

    I will sent e-mail to Kollmorgen I will ask them for datasheet for resolver Kollmorgen N/S 97307707 type: 04S19RX342g17F00



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    Default Re: Help with servo motor

    Hi,

    You short the stator wires and rotate the armature shaft 1 revolution and count the 'bumps' this is the No. of poles.
    Al.
    That's a good way of determining the number of motor poles but the number of resolver poles may differ.

    Craig



  12. #12
    Community Moderator Al_The_Man's Avatar
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    Default Re: Help with servo motor

    I was posting if the idea was to turn it into a BLDC/incremental encoder where drives where there are much cheaper options and also step/dir versions if needed.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Default Re: Help with servo motor

    Our Kollmorgen AKD-P-01206 , approx. $1000, will run that motor very well. We and perhaps others, stock it. Just type in resolver pole count, adjust resolver ratio if needed. Watch GUI while rotate motor 1 rev. Change res pole count until it reads 1 rev on resolver picture in software.

    Sent from my SM-G900V using Tapatalk

    Mike@@@KilroyWasHere.com


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Help with servo motor

Help with servo motor