Looking to get 65v dc out of 110v ac

Discussion in 'General Electronics Chat' started by jchal3, Dec 13, 2009.

  1. jchal3

    Thread Starter Member

    Dec 13, 2009
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    Hello,

    This is my first post, and I am by no means an electrical engineer. I am working on building a cnc router, and have managed to aquire three stepper motors and drivers. I also managed to get the schematics for these drivers and motors, however it shows how they were hooked up on a previous packaging machine. The drivers state that they have a 75v dc max input, and the motors run on 65vdc. The trick is that they are running off of 110vAC. It looks like the 110vac goes through a bridge rectifier, but that puts out 166vdc (on the multimeter). I need to get this 110vac changed over to 65vdc. Any help would be appreciated.

    Thanks,
    Jason
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    At 65VDC, what current do your motors require?
     
  3. jchal3

    Thread Starter Member

    Dec 13, 2009
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    The tag reads:

    Is(DC) 7.9 a
    Vs(DC) 65V
    Po: 337w

    I'm assuming you are looking for the 337w.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Ahh, each motor has 7.9A on it?

    Or is that the housing where the power supply USED to be?
     
  5. SgtWookie

    Expert

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    You're looking at spending a good-sized chunk of change to get that kind of power converted. You knew that, right?
     
  6. jchal3

    Thread Starter Member

    Dec 13, 2009
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    had no idea. Like I said the motors and drivers were freebies, didn't know they were going to take a lot of money. Would you mind giving me the bad news as to how to accomplish it, and I'll look at possibly buying drives and motors.

    I appreciate the help
     
  7. jchal3

    Thread Starter Member

    Dec 13, 2009
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    Sarge,

    If you wouldn't mind giving me your e-mail address I could email you scanned version of the schematic I am trying to replicate. I am under the impression that I already have all the parts that I needed. (the drivers and motors isn't all that came for free) Maybe you could help me decipher it.

    thanks
     
  8. SgtWookie

    Expert

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    You might find something suitable on the surplus market.

    MPJA has these:
    http://www.mpja.com/prodinfo.asp?number=6643+PS
    65v unregulated 7.7A supplies, $205 each. The bad news is that unloaded voltage is 75.2v. Basically, they're just a big transformer with a big capacitor.

    I don't know what kind of environment you're installing this thing in, but if it's a home installation, you'll probably need a supply that'll run off 240VAC. Otherwise, you'll have problems trying to pull enough current from a 120v circuit.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    I don't give out my E-mail address for obvious and not-so-obvious reasons.

    The forum is all about sharing knowledge. To do things via E-mail would jam up my E-mail, defeat the purpose of the forum, and deprive you of other knowledgeable input.

    Why don't you just attach them to a post?

    Use the "Go Advanced" button under the reply box, and then click the "Manage Attachments" button on the next screen. You'll get a popup window that will allow you to locate and attach image files for upload.
     
  10. jchal3

    Thread Starter Member

    Dec 13, 2009
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    That makes total sense.

    I think it worked. What you have said makes sense. the L1-L3 coming in at the top of the sheet are 230 3 phase. I was assuming that the transformer coming off of that was chaging it to 110v. But from what you have said it must me the 65V power supply. What do you think.
     
  11. SgtWookie

    Expert

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    Oh, boy. Did you have the bridge connected to the logic when you powered it up?

    [eta]
    Is TX1 still in the unit? The transformer?
     
  12. SgtWookie

    Expert

    Jul 17, 2007
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    Anyway, if the 3-phase was indeed 240v, phase-to-phase it was 208v.

    If TX1 were still in there, it might be possible to get you at least in the ballpark; operating on 240v you'd have 75v instead of 65v. That might be chopped down to 65v using a large inductor, a power MOSFET and a buck-type switching controller.
     
  13. jchal3

    Thread Starter Member

    Dec 13, 2009
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    No, tx1 is not still on the unit. I took the two leads coming out of tx1 and replaced them with a 110v plug. Please don't tell me I have destroyed everything.
     
  14. SgtWookie

    Expert

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    OK, I'll just repeat what you first wrote:

    Let's see, 166V is about 75v * 2.2.

    Are there fuses in the drivers/logic boxes?

    Were their any loud "bangs" when you first applied power?
     
  15. jchal3

    Thread Starter Member

    Dec 13, 2009
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    Right... Got it I'm an idiot. The power stayed continuous through the output while i was metering it. Any slim chance I didn't hurt it? I know it sounds dumb but it didn't pop smoke or sizzle or anything like that.
     
  16. SgtWookie

    Expert

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    I'm not telling you that you're an idiot. You made an honest mistake. I'm just glad you survived it.

    I honestly can't tell you whether or not you fried anything.

    If you smell a burnt smell, that would not be a good sign.

    I only know what you've told me about them, and what's on the schematic.

    I see there's a "5410" on the driver boxes. If there is a manufacturer and model number on them, or inside the box, maybe you can find a schematic or troubleshooting chart for them.
     
  17. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    (trying to put this in laymans terms)

    A 7 amp stepper motor does not require 65v AND 7 amps. A 7 amp stepper normally runs at about 1.5 volts. So it's power needs are 7 * 1.5 (about 10 watt) per phase. With a microstepping driver it will average 1.4 phases on so total average motor power is around 14 watts.

    The drivers are chopping drivers (ie switchmode or SMPS drivers) and will run at about 75% efficiency so for 14 W out to motor then will need about 20 W input, so they need about 65v and 0.3 amps input.

    So to run 3 motors you will need about 65v at 1 amp (60 W total).

    The high (65v) input allows much faster motor speed but it will also cause extra vibration etc (higher excitation energy). If you only need hobby motor speeds of a few revs per second I would use about a 24v 60 watt supply, this will give lower noise, less vibration and resonance, and a much safer voltage overhead for your drivers to reduce the chances of driver failure.

    Also, you might choose to run the motors at less than 7 amps, provided they have enough power to do the job running at lower current reduces noise, vibration, motor and driver heat etc etc.
     
  18. jchal3

    Thread Starter Member

    Dec 13, 2009
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    sarge,

    Thanks for all your help. I didn't smell anything so hopefully I got lucky. It is a Pacific Scientific 5410-010 stepper drive. The reason that I got it as a freebie is because it is no longer supported. haha it figures right haha. Anyway, I'm going to try to get online with some of these guys that claim they can fix them, and maybe I'll be able to get a connection diagram.
    One more question. What voltage is tx1 putting out. That has been the big question mark in my head since I started this thing. I was thinking 110v ac, it looks like you said 208v ac. Am I reading this right?
     
  19. jchal3

    Thread Starter Member

    Dec 13, 2009
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    RB,

    Thanks for the resonse. Just to clarify, you are saying if I hook up a 24v 60watt power supply that might be enough to get my motors moving?
     
  20. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I don't know the details for that exact driver, but generally chopper stepper drivers can operate from a very broad input voltage range. It would be rare to require a particular high input voltage.

    It is common for drivers just to list their maximum input voltage so I would hazard a guess that the "65v" is a maximum. It's also common for chopper drivers to work reliably right down to 20v although some will list 24v as a minimum Vin.

    In your case if you can't find an exact spec sheet for your drivers I would connect it to a 24v DC supply, set the motor current low (like 1 amp or 2 amps) and see if it runs your motor.

    I would be very surprised if it NEEDS 65v to work properly, but like I said I have never used that particular controller.

    A google search just brought up a ton of firms that repair that model (dunno if that's a good thing) but didn't find any specs. Probably with a better google search you would get some voltage specs for that model driver or some specs for a similar model in the range.
     
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