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3 phase ac motor speed control — Parallax Forums

3 phase ac motor speed control

Alejo83Alejo83 Posts: 28
edited 2014-05-02 12:46 in General Discussion
Hello, I am just wondering If there Is a way to control the speed of an ac motor with the basic stamp 2. What I basically need Is to change the speed of the motor through a knob or any input device from minimum to maximum, that's all. The big issue is that it is a big motor, here are the specs:

- 5 hp
- 208v ac
- 15 amps continues current (almost the 24 hours of the day)
- three face induction motor

what is the easiest way to drive this motor?

I will really appreciate your input, thank you!

Comments

  • FranklinFranklin Posts: 4,747
    edited 2014-05-01 15:31
    Is this motor installed and working? (do you have 3 phase power?)
  • Alejo83Alejo83 Posts: 28
    edited 2014-05-01 15:37
    Yes, it is installed with a leeson's controller but they are quite expensive and I want to start making my own controls due that we buy like 10 of those every year.
    I just need to know what is the most simple circuit design to drive this motor with the basic stamp 2.
  • Alejo83Alejo83 Posts: 28
    edited 2014-05-01 15:42
    Thanks so much for your fast response!
  • GenetixGenetix Posts: 1,754
    edited 2014-05-01 16:31
    You should consult an EE who specializes in Power electronics or a company that makes power electronics.
    Those voltages and currents are dangerous and lethal. Do you realize that is over 3 kW?
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2014-05-01 16:57
    Genetix wrote: »
    You should consult an EE who specializes in Power electronics or a company that makes power electronics.
    Those voltages and currents are dangerous and lethal. Do you realize that is over 3 kW?

    I would help but I know its not worth the $$ to blow loads of fets to make a device that is better COTS .
  • Alejo83Alejo83 Posts: 28
    edited 2014-05-01 17:13
    Peter KG6LSE wrote: »
    I would help but I know its not worth the $$ to blow loads of fets to make a device that is better COTS .

    Thank you so much for all your comments and I understand everything that you guys just said but I will really appreciate if you guys can provide at least link where I can see ways of how to accomplished this project.

    Thank you so much and have great day!
  • FranklinFranklin Posts: 4,747
    edited 2014-05-01 18:10
    This might help you get started http://cache.freescale.com/files/microcontrollers/doc/app_note/AN2154.pdf or this
    http://www.freescale.com/files/microcontrollers/doc/app_note/AN1664.pdf
  • Alejo83Alejo83 Posts: 28
    edited 2014-05-01 18:36
    This is really helpful! I am working on it right now, millions of thanks again!
  • stamptrolstamptrol Posts: 1,731
    edited 2014-05-02 04:55
    By all means, the easiest and lowest cost way to proceed is to purchase variable speed drive and use the stamp to control it with a 0-5 volt or 0 - 10 signal. Modern drives have relay contact inputs for on, off, fwd, rev and can use an analog signal for speed.

    I've used several drives from Automation Direct. In the small size you are contemplating, they are very economical.

    The design of AC drives is very specialized and folks can spend their whole careers perfecting them.

    Cheers,
  • ellipserellipser Posts: 43
    edited 2014-05-02 06:16
    Franklin wrote: »
    This might help you get started http://cache.freescale.com/files/microcontrollers/doc/app_note/AN2154.pdf or this
    http://www.freescale.com/files/microcontrollers/doc/app_note/AN1664.pdf

    That's a pretty good link.

    And, just to the poster who said those voltages are lethal. Yes they are! But there's a safe way of working with them. Just work with them safely, never touching a wire with your hands when it's energized (only with a multimeter, etc.) and everything will be OK.

    That simple rule of no-touching except with a multimeter until a circuit is confirmed to be un-energized will keep you safe. I suspect you know this or you wouldn't be the one changing out the existing drives 10 times a year.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2014-05-02 06:18
    +1 to what stamptrol said above.

    Search on ebay for things like variable frequency drive
  • PropGuy2PropGuy2 Posts: 360
    edited 2014-05-02 06:43
    I have done 3 phase motor controls very successfully by using the suggestion in post #10. Buy a controller from Automation Direct and use the Stamp to control the 5 volt logic input(s) In addition I would use a four (4) button setup for any motor control and for safety. That is - Power On / Power Off / Motor Run / Motor Stop VS just - Motor Run & Motor Stop 270 VAC 3-phase is a lot of power gone awry (death wish) if there are any mis-steps in your 3 phase motor control circuit board design.
  • Alejo83Alejo83 Posts: 28
    edited 2014-05-02 06:48
    Thank you guys! You are all really helpful and yes I already know how to work with those lethal voltages and currents but I also like the idea to buy one of those small controls where I can use the basic stamp and a ovoid the time consuming of designing one! Have an amazing day!
  • Alejo83Alejo83 Posts: 28
    edited 2014-05-02 06:50
    Do you mind to provide a link of one those controls! Thanks so much for your input!
  • ellipserellipser Posts: 43
    edited 2014-05-02 08:30
    Alejo83 wrote: »
    Do you mind to provide a link of one those controls! Thanks so much for your input!

    http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR11.TRC1.A0.H0.X3+phase+vfd&_nkw=3+phase+vfd&_sacat=0&_from=R40



    Just type in "3 phase VFD" (variable frequency drive) into ebay, and then check out the manuals to make sure you have proportional control on a model you're considering.

    Here's a specific one you could use that meets the requirement of 208 VAC input for 5HP motor.
    http://www.ebay.com/itm/Allen-Bradley-22D-B017N104-PowerFlex-40P-VFD-5hp-200-240V-60-day-warranty-/360911359658?pt=LH_DefaultDomain_0&hash=item5407fe4eaa

    For every one I've ever seen, you don't need a microcontroller to do proportional control. You can just wire it up to do on/off, proportional using a power supply and a potentiometer etc.
  • Tim-MTim-M Posts: 522
    edited 2014-05-02 12:46
    I will also back up Stamptrol's and other recommendations for Automation Directs AC-Variable Frequency Dives. They are the most economical to be found, come in different motor hp ranges, and very feature rich and flexible to use. I have put several into every day service which have been bullet proof for years... highly recommended!

    www.automationdirect.com

    All categories of products are on the left sidebar, including 'Drives'

    Tim
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