I need help with a pan cake motor

Discussion in 'The Projects Forum' started by modobo, Apr 23, 2013.

  1. modobo

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    Apr 23, 2013
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    Hi, I have a DC 3 phase brushless motor with hall sensors and I have been sifting through the internet trying to find a circuit that can drive it. I dont mind building the circuit from scratch if the components were available. I am hoping though, to find an all in 1 IC or drive unit.

    I am hoping to use a pc to drive the microelectronics aspect of the circuit so my main concern is the power drive section.

    This motor comes on a LG DD washing machine and should reach 1200 rpm.

    Thanks
     
  2. #12

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  3. strantor

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    I've never tried to make a BLDC motor controller for something so small, but I have entered the weeks-long research & planning phase of building a larger one, for a multi-KW motor. What I found is that there's a lot to it. building such that it works, is efficient, and doesn't self destruct, could take several months and many design revisions and blown parts. Better to start with something where all or most of the leg work is done for you. A lot of people would use a R/C car/plane ESC for what you want. That's a solution in a box for you. If you want to get more into the nuts & bolts of it, you could use an arduino with a premade motor shield. Check this out: http://scolton.blogspot.com/2010/06/hexbridge-shield-bldc-and-this-silly.html
     
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  4. modobo

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    Apr 23, 2013
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    Hi 12, Thanks for the link but I dont find anything I can use there, I don't even know if the motor I have is a PLX or an SLE:confused:. I doubt its either of those things, its just a simple DC 3 phase pcm drive.
     
  5. modobo

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    Apr 23, 2013
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    These pancake motors have been around very long now and I believe most of the leg work must have been done already. The original chip that controlled this motor had its label erased by the company so I cant get a data sheet on it but I know its going to be on the market somewhere or an equivalent at least.
     
  6. strantor

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    There are BLDC control ICs out there, but I haven't seen one that is self contained and drives motors directly. They are meant to be the control stage of a larger circuit, requiring drive stage ( mosfets or IGBTs). I could have missed something though, as I said, I never looked for anything small.

    Search microchip.com for BLDC. They have a ton of products that would interest you, but more importantly they have a ton of app notes on the topic that you can use to educate yourself about how these things work.
     
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  7. modobo

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    Thanks, I'll check it out
     
  8. shortbus

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  9. modobo

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    Thanks Shortbus, the chip you suggested would had been exactly what Im looking for except that the voltage is too low. The motor was recently driven by a controller that looked a bit like a MOSFET block. On one side of the chip it had about 10 tiny terminals and on the other side it had 5 big terminals. Two of those terminals marked +&- was the supply voltage for the chip and the other 3 served the motor. Across the input when the system is on, the input voltage measures 318v DC.

    I would need something that can handle this high voltage..
     
  10. shortbus

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    The chip I linked to can be used at any voltage if you use it to drive mosfet gate drivers.

    What motor are you using that takes 318V DC? Sorry went and reread the first post. Have you checked Ebay for Fisher&Paykel drivers. They used to be listed.
     
  11. #12

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    I was just tossing in something strantor posted a few weeks ago. I guess I missed:(

    Sorry about that. Probably should have shut up and waited for the local expert on this subject to post.
     
  12. strantor

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    How big is a washing machine motor? I've never had one open, but I was assuming fractional hp, tiny motor like what's in the new brushless cordless drills. Now that I see 318V and shortbus' Fisher and Paykel suggestion and reflect on your bardac suggestion, I'm thinking it must I that is off the mark.
     
  13. modobo

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    Apr 23, 2013
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    Hi, Im trying to run a motor this big https://encrypted-tbn1.gstatic.com/...cjoBzxRKeJnpeH6a9M_DgfYgM9PKBIN5jCNvUp7ZK8sYF

    I hope this link shows the image but if not just cut and past. Its a good idea to drive the MOSFETs with the chip but I dare not try and design the circuit myself, my knowledge of circuit analysis is not that robust however I know it can be done with under 10 components.

    I've seen a few circuits but the components for those circuits aren't readily available so the search goes on..
     
  14. strantor

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    Well I found a likely candidate for what probably used to control the motor here. But something tells me you won't need load size presets and rinse cycles for your application. That motor is a lot bigger motor than I had in mind, probably >1KW so my previous suggestions were no good. Sorry for that; I shouldn't have made assumptions. You are not going to find a single self contained IC than can control this motor. You are going to need a full bridge of MOSFETs or IGBTs to go along with it. I think you're into the arena that I was in - that is, the arena where it makes more sense (time wise AND money wise) to buy a commercial off the shelf device rather than attempt to design your own. The drives that #12 linked to are nice, but they are several thousand dollars; considering you're re-purposing a washing machine motor, I assume your budget is less than that. I am returning to my suggestion of a hobby R/C ESC. Check this out.
     
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  15. modobo

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    Apr 23, 2013
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    Thanks Strantor, great links, Im still sifting through freescale.com. One item that has caught my attention is their MC56800 and I think I'll have to spend the next few days investigating if this will be a good choice
     
  16. strantor

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    So you're going to be hard headed and try to reinvent the wheel then. Sounds good. But keep the link to the $60 R/C ESC handy for if/when you realize how deep you are in over your head. In the mean time, we are always here to help.

    I could not find ANY info for the MC56800, even on the freescale website. Can you post a link to whatever it is you're reading?
     
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  17. modobo

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  18. strantor

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    I have a feeling that you either didn't look at the link to the r/c esc that I posted, or didn't know what you were looking at if you did. This thing is a sensored brushless motor controller for $60 rated for 100 amps and I'm fairly confident it will work. You are not going to be able to design your own brushless controller for less than that or even close to it (considering your time). These are speed controllers for monster r/c planes with sensored bldc motors of similar hp to what you have. Seems like a fairly plans and play solution to me.
     
  19. shortbus

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    But the ESC won't work with his 318VDC. :)
     
  20. strantor

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    the windings can be easily rearranged.
    www.sabels.co.za/FP.pdf
     
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