Page 1 of 2 12 LastLast
Results 1 to 10 of 14
  1. #1
    25+ Posting Member
    Join Date
    Jun 2007
    Location
    Alberta, Canada
    Posts
    46
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Using 3 phase AC motors for platform

    Ok, I'm in the middle of the concept stages of my motion platform. I have done quite a bit of research, and found that most of the professional electric motion platforms use powerful 3 phase AC motors.

    So, considering it would be easy to add a single phase 240v/60hz line in my basement and use single phase input to 3 phase output motor inverter controllers, does anyone see a downside to using 3 phase vs. low volt DC?

    This is similar to what I would like to build:
    [ame="http://www.youtube.com/watch?v=UDtb8lePiys"]YouTube - Cal Poly Flight Motion Sim In-Action[/ame]

    Thanks,

    Dutchboy

  2. #2
    150+ Forum Groupie Roland's Avatar
    Join Date
    Apr 2006
    Location
    Netherlands
    Posts
    195
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    It all depends on whether you're going to build or buy, and your budget.
    Low voltage DC motors are relatively easy to drive with either homebuild MOSFET drivers or low cost commercial avaliable drivers. Low / medium power DC motors are not that expensive either. As you mentioned you're going to build a single seater small GA platform, the DC motor power requirements would be OK.

    With 3-phase motors, your only option is buying and my guess is that prices will be stiff.
    RR

  3. #3
    25+ Posting Member
    Join Date
    Jun 2007
    Location
    Alberta, Canada
    Posts
    46
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    3-phase action

    Thanks for the reply Roland. I have actully found some 3-phase motors (inline gearmotor, 1/4 hp, 125rpm, 120 torque in-lb, continuous duty) for $170 US each.
    http://www.surpluscenter.com/item.as...tname=electric

    The controllers I was thinking about are about $120 US each.
    http://www.surpluscenter.com/item.as...tname=electric

    So, in total, around $900. Not bad. I may look for something with a little more power though.

    Dutchboy

  4. #4
    1000+ Poster - Fantastic Contributor AndyT's Avatar
    Join Date
    Jun 2006
    Location
    Oahu, Hawaii
    Posts
    1,392
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Wink Motors

    Another thing to factor in is that when you build the platform you design in 'balance' so that the whole works needs very little power to move it. And if you set the balance point taking into account the weight of the pilot and Copilot (if the sim is that big) then you really do not need that much power. Most of the sims you see running motion on this site are using very small DC motors. (under 1 hp) The 3 phase motors you are looking at are OK, but the electrical considerations for them adds to the overall complexity of the project.. A general rule of thumb for motion, the smaller and simpler you can get by with, the better.

    I personally am using two 12v wheelchair drive motors controlled by a Phidgets servo controller. So far I have not decided on software but since I'm running FSX I just might have to write my own. (Hey Alan!, hint hint)

    If you really want lots of power, then look at winch motors. They run 12v and can pull a ton or two depending on the winch.
    God's in command, I'm just the Pilot.
    http://www.geocities.com/andytulenko/

  5. #5
    25+ Posting Member
    Join Date
    Jun 2007
    Location
    Alberta, Canada
    Posts
    46
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    3-phase or DC

    Well, I am thinking of moving to a 3 DOF platform, in which I would need the power to lift the platform to create heave. This would require more than low power DC if I wanted it to be fast. I'm sure I could use winch motors if I didn't care how fast it was. The more I think about it, the more I think 3-phase is the way to go for what I want. It really isn't that hard to wire those controllers to the motor. Especially because those controllers only need 240v single phase input.

    The cost of 3-phase isn't that bad if I go for 1hp or less. I'll stick to the PWM controllers and user a servo control board. I should be able to do this for around $1500.

    I'm fine with the cost being a little higher if it means more speed and the addition of heave.

    Dutchboy


    Quote Originally Posted by AndyT View Post
    Another thing to factor in is that when you build the platform you design in 'balance' so that the whole works needs very little power to move it. And if you set the balance point taking into account the weight of the pilot and Copilot (if the sim is that big) then you really do not need that much power. Most of the sims you see running motion on this site are using very small DC motors. (under 1 hp) The 3 phase motors you are looking at are OK, but the electrical considerations for them adds to the overall complexity of the project.. A general rule of thumb for motion, the smaller and simpler you can get by with, the better.

    I personally am using two 12v wheelchair drive motors controlled by a Phidgets servo controller. So far I have not decided on software but since I'm running FSX I just might have to write my own. (Hey Alan!, hint hint)

    If you really want lots of power, then look at winch motors. They run 12v and can pull a ton or two depending on the winch.

  6. #6
    150+ Forum Groupie Roland's Avatar
    Join Date
    Apr 2006
    Location
    Netherlands
    Posts
    195
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    The prices at surplus center aren't bad at all.
    Had a look at the specs of the motors: If you want the 3 motors to carry the full weight of your platform, (say 120kg like mine) each motor would have to sustain 40kg. The torque of the motor says 120 inch-lbs which is 13.6Nm. with arm-length of 0.2m you would get 68N of force which can lift only 7kg. So it won't work for a non balanced platform.
    If you use a big spring to offset the platform weight, it will still be critical, as depressing the spring also takes extra force. Seems that the torque of the motor is not sufficient (or maybe I made a mistake, I can only calculate in metric)
    Just for reference: My homebuild actuators produce ~ 43N of force per Ampere. At 10 Amp, 430N gets a balanced 120kg platform really moving!
    I use pulley / belt system for gearing as it can take lots of abuse. Standard gears don't like sudden reversal at high torque.

    To avoid dissappointments, make sure you do these kind of calculations before you buy!
    RR

  7. #7
    1000+ Poster - Fantastic Contributor Bob Reed's Avatar
    Join Date
    Oct 2005
    Location
    Holley, New York U.S.A.
    Posts
    1,880
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    I think as well keep in mind most commercial platforms are hydrolic so the 3 phase motors are driving hydrolics.
    Bob Reed

  8. #8
    25+ Posting Member
    Join Date
    Jun 2007
    Location
    Alberta, Canada
    Posts
    46
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    3-phase force

    Perhaps you guys are right. I just saw this sim and got excited about the power:
    [ame="http://www.youtube.com/watch?v=UDtb8lePiys"]YouTube - Cal Poly Flight Motion Sim In-Action[/ame]


    About your calculations - I'm getting 162.69Nm from 120 inch-lbs. according to trusty google:
    http://www.google.ca/search?hl=en&sa...on+meters&meta=

    Perhaps I am missing something in the equation though.

    Dutchboy



    Quote Originally Posted by Roland View Post
    The prices at surplus center aren't bad at all.
    Had a look at the specs of the motors: If you want the 3 motors to carry the full weight of your platform, (say 120kg like mine) each motor would have to sustain 40kg. The torque of the motor says 120 inch-lbs which is 13.6Nm. with arm-length of 0.2m you would get 68N of force which can lift only 7kg. So it won't work for a non balanced platform.
    If you use a big spring to offset the platform weight, it will still be critical, as depressing the spring also takes extra force. Seems that the torque of the motor is not sufficient (or maybe I made a mistake, I can only calculate in metric)
    Just for reference: My homebuild actuators produce ~ 43N of force per Ampere. At 10 Amp, 430N gets a balanced 120kg platform really moving!
    I use pulley / belt system for gearing as it can take lots of abuse. Standard gears don't like sudden reversal at high torque.

    To avoid dissappointments, make sure you do these kind of calculations before you buy!

  9. #9
    150+ Forum Groupie Roland's Avatar
    Join Date
    Apr 2006
    Location
    Netherlands
    Posts
    195
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Keep in mind that the motor torque spec is in pounds-inch, not pounds-foot.
    120 inch pounds = 13.55Nm
    http://www.onlineconversion.com/torque.htm
    RR

  10. #10
    25+ Posting Member
    Join Date
    Jun 2007
    Location
    Alberta, Canada
    Posts
    46
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    3-phase

    Of course! I missed that, thanks! I think I'm going to stick to low volt DC and my original balanced platform idea. Thanks for the help guys.

    Dutchboy

    Quote Originally Posted by Roland View Post
    Keep in mind that the motor torque spec is in pounds-inch, not pounds-foot.
    120 inch pounds = 13.55Nm
    http://www.onlineconversion.com/torque.htm

Page 1 of 2 12 LastLast

Similar Threads

  1. Update to my motion platform - phase 1 complete!
    By louisgr in forum My Cockpit Update
    Replies: 3
    Last Post: 08-01-2008, 10:33 PM
  2. Approach phase clarification
    By mmakela in forum Dodiano's Airbus Forum
    Replies: 12
    Last Post: 07-05-2008, 06:35 AM
  3. Phase 1 737NG complete
    By David Rogers in forum My Cockpit Update
    Replies: 9
    Last Post: 11-27-2007, 10:22 PM
  4. A320 Approach phase
    By iperne in forum PM General Q & A
    Replies: 1
    Last Post: 09-18-2007, 06:49 AM
  5. Jims Motion platform with GearMotors or Step motors
    By gflinch in forum Cockpit Parts and Motion Platforms
    Replies: 21
    Last Post: 07-01-2006, 02:12 AM