VFD Can they run a motor at 1.5 Hz - Page 5
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  1. #81
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    Quote Originally Posted by MattiJ View Post
    So you think that the bldc motor without electronics is going to run if you connect it directly to dc power supply?

    Or is the bldc motor going to run if you connect it to 3-phase vfd?
    ??
    Are you out of your tree? It's a DC motor. It damned well better run directly off DC!

    All a "brushless" DC motor is.. is an ordinary DC motor, same type, etc, as one WITH brushes, wherein solid-state switching has replaced mechanical switching of brushes and commutator segments. That has historically been done on/in the motor housing.. Hall effect sensors have to be where the shaft is to know where the coils are, just as the commutator did. Switching OF said coils needs to be where THEY are as well.
    Where it otherwise one could need over a hundred leads presented remotely on some motors.

    The only difference between a "brushed" DC motor and a brushless one is no arcy-sparky and "allegedly" no wearing parts. So, far, however, no brushless motor has come close to the "maintained" life of brushed ones (over a hundred years).

    It is yet to be proven the solid-state components will live as long in rude environments as even the brushes do (typically 2,000 Power ON hours).

    Bottom Line? So far, the "volume" use for brushless is primarily in expendables, no service wanted. Or no service even POSSIBLE. Replace or abandon. Do not service.


    They work off the specific DC voltages they were designed for. Period.

    Want to run one off a VFD?

    Not hard. Put a 3-Phase full-wave bridge on its output, sum the DC, filter it, and you have the DC the DC motor expects. Whether your VFD is equipped to VARY the voltage rather than the Hz is another matter.

    Soooo. skip the rectifier, lock the VFD @ 60 Hz, feed the output to a 3-Phase-only DC Drive.


    Kinda like routing by way of John O'Groats to get from Blackheath to Lewisham, but there you have it.

    No VFD need apply. Those are meant to be utilized with ...wait for it... Poly-Phase AC motors.


  2. #82
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    As a matter of reference many Bosch servo drives can be configured to run asynchronous motors.
    What people usually call BLDC motors are really just poly phase synchronous motors.
    Run just fine on a properly configured VFD...since that's all a servo drive is is really smart VFD.
    The old ATS drives could turn a motor just fine with out their encoders.

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    Quote Originally Posted by thermite View Post
    ??


    All a "brushless" DC motor is.. is an ordinary DC motor, same type, etc, as one WITH brushes, wherein solid-state switching has replaced mechanical switching of brushes and commutator segments. That has historically been done on/in the motor housing.. Hall effect sensors have to be where the shaft is to know where the coils are, just as the commutator did. Switching OF said coils needs to be where THEY are as well.
    Where it otherwise one could need over a hundred leads presented remotely on some motors.

    Ah, now I see where your misunderstanding is coming from. Small fans and such work as you said. Lets just call them electronically commutated dc motors and ignore them after that.

    BUT typical bl motor on cordless tools does not work like that. Read the links I posted before and forget your dc prejudice just for while and you'll see what this is about.

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    Quote Originally Posted by MattiJ View Post
    Ah, now I see where your misunderstanding is coming from. Small fans and such work as you said. Lets just call them electronically commutated dc motors and ignore them after that.

    BUT typical bl motor on cordless tools does not work like that. Read the links I posted before and forget your dc prejudice just for while and you'll see what this is about.
    Look around. I am not the one with a "prejudice".

    I use far, far, more AC motors than DC, and some of them come in "packages" with inverters built-in. Linear inverter compressor on my LG fridge/freezer, similar goods on the washer & dryer. I would NOT NEED two 10 HP Phase-Perfect plus a 10 HP RPC if I was exclusively a Dee Cee shop, now would I?

    I just happen to be aware of their strengths and weaknesses for various purposes.

    Not a "predjudice". Trying to break OTHERS of their blindness.

    The "prejudice" is coming from those who believe - worse yet, proselytize - a VFD as some form of heaven-sent MAGIC that obsoletes all other forms of motive power control.

    Get f*****g REAL, guys! A VFD is just one more arrow of many in the quiver.

    Servos ain't dead. Steppers yet live. So do ignorant solenoids.

    And then? The unit-count on consumer goods alone of ignorant single-phase AC motors must still dwarf that of 3-Phase, VFD'ed or not.

    Multiple millions of motor vehicles, aircraft, and watercraft still crank their IC engines with DC starters. What's to be gained by making those more expensive and less reliable?


    VFD must class as some form of "recreational drug" the way some of you have habituated to them as a universal answer.

    As to your link? I could give a shit!

    If/as when such technology shows up in my hand as a power tool?
    BFD. It will get used, not re-engineered.

    Fair warning: last three Makita goods were discarded within the year. Hell will freeze before those over-priced under-reliable feather-merchants get another crack at MY budget.

    And FWIW? Neither you nor anyone else has yet shown "VFD" taking any significant share of the powered hand tool market, corded or otherwise.

    WTF are you lot smoking out there, anyway? Very Fine Drug?


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    Quote Originally Posted by thermite View Post


    As to your link? I could give a shit!


    And FWIW? Neither you nor anyone else has yet shown "VFD" taking any significant share of the powered hand tool market, corded or otherwise.


    At least I tried

    Usually you are quite booksmarts but something is "lost in translation" in here. I'm a half-witted electrical engineer that has been slightly involved in some BLDC drive electronics design but I'm not sure if I can or want to try to explain the differences or similarities between VFD and BLDC motor "electronic control box" any better than this if you don't even bother to read the links provided.

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    Quote Originally Posted by MattiJ View Post
    At least I tried

    Usually you are quite booksmarts but something is "lost in translation" in here. I'm a half-witted electrical engineer that has been slightly involved in some BLDC drive electronics design but I'm not sure if I can or want to try to explain the differences or similarities between VFD and BLDC motor "electronic control box" any better than this if you don't even bother to read the links provided.
    I *DID* read them. So what?

    I'm as much a pragmatic Economist as a Technologist.

    When it adds cost, reduces reliability, makes repairability into DISPOSABILITY, and has ZERO positive effect on the utility?

    I call that a regression, not an advance.

    Had some holes to make today. Outdoors, no way to get the goods to the drillpressen.

    My M12's weren't up for driving a 2" carbide tipped hole saw through mild steel. Genuine Scintilla, CH division of otherwise-useless-for-a-score-of-years Robert-the-"Boche" corded 3/8" hand drill motor, OTOH? And it was JF "done".

    Had that, or a similar Metabo, not been to-hand and someone had handed me a "Makita"?

    Wudda simply gotten into the motorcar and gone off to buy a real drill motor.


    I pay too much attention I'll catch y'all sneaking VFD's into an ignorant Bic Biro or butane lighter.

    I'd really rather not even be aware of that when it cometh. Too many failure modes that need never have BEEN failure modes already.

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    Bigger cordless drills have reached the practical limits how much torque you want from hand tool. If you go ice fishing in here Its common sight to see heavy duty brushless drill on the end of 4 or even 8" ice auger.

    Has created also a new type of recreational injuries, strained wrists and broken thumbs when the ice auger suddenly jams.

    Rather sizeable side handle is not just for giggless on the bigger brushless tools:

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    Quote Originally Posted by MattiJ View Post
    Bigger cordless drills have reached the practical limits how much torque you want from hand tool. If you go ice fishing in here Its common sight to see heavy duty brushless drill on the end of 4 or even 8" ice auger.

    Has created also a new type of recreational injuries, strained wrists and broken thumbs when the ice auger suddenly jams.

    Rather sizeable side handle is not just for giggless on the bigger brushless tools:
    Winter 1949-50. Lake Champlain. Steel auger. Wooden Tee handle.

    "Battery" didn't go dead less'n the fisherman froze to death or such... (ISTR one DID. Tough winter, that one was.)

    And... the power source could catch the fish, carry it home, scale the fish, enjoy a meal, and still have energy left to shag a smile onto the face of his lady before dropping off to a good night's sleep.

    Clever Japanese have all that OTHER s**t automated, too.


    But I am NOT interested!


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    Quote Originally Posted by thermite View Post
    Winter 1949-50. Lake Champlain. Steel auger. Wooden Tee handle.

    "Battery" didn't go dead less'n the fisherman froze to death or such... (ISTR one DID. Tough winter, that one was.)

    And... the power source could catch the fish, carry it home, scale the fish, enjoy a meal, and still have energy left to shag a smile onto the face of his lady before dropping off to a good night's sleep.

    Clever Japanese have all that OTHER s**t automated, too.


    But I am NOT interested!

    Luddites...that's fine.
    The poly phase variable frequency drive, with and without position feed back is here. It's superior in most ways to D.C. Brushed motors.
    Whether running asynchronous or synch.
    Why do you suppose every computer on the planet uses BLDC fans? Reliability and cost...and efficiency.

    D.C. Has a place...as a buss for smart commutation.
    I haven't seen a D.C. Brushed motor in a new industrial application in a decade at least.
    My new power tools Bury my old ones because of the commutation efficiency.

    Yep...the starter motor on cars is still brushed...I haven't seen a brushed motor in a long time.

    Kids Prius uses a BLDC starter.


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