Brushless DC Motor, How it works ?

Brushless DC Motor, How it works ?

In order to make the operation more reliable, more efficient
and less noisy, the recent trend has been to use brushless dc motors
They are also lighter compared to brushed motors with the same power output
The brushes in conventional dc motors wear out over time and may cause sparking
Thus the brushed dc motor
should never be used for operations that demand long life and reliability
let’s see how a brushless DC motor works
the rotor of a BLDC motor
is a permanent magnet
the stator has a coil arrangement as
by applying DC power to
the coil, the coil energize and
become an electromagnet
the operation of a BLDC is based on the
simple force interaction between the
permanent magnet
and the electromagnet
in this condition when the coil A is
energized the opposite poles on the
rotor and stator are attracted to each
as the rotor nears coil A coil B is
as the rotor near coil B coil see is
after that coil as energized with the
opposite polarity
this process is repeated and the rotor
continues to rotate
a humorous analogy to help remember it
to think about BLDC operation like the
story of the donkey and the Carrot
where the donkey tries hard to reach the
carrot but the Carrot keeps moving
out of reach
even though this motor works it has one
you can notice that at any instant
only one coil is energized. The two dead
coils greatly reduce the power output of
the motor
here is the trick to overcome this
problem. When the rotor is in this
along with the first coil which pulls
the rotor
you can energize the coil behind it in
such a way that
it will push the rotor. For this
instant a same polarity current is
passed through the second coil
the combined effect produces more torque
and power output from the motor
the combined force also makes sure
that a BLDC has a beautiful constant
torque nature
with this configuration two coils need
to be energized separately
but by making a small modification to
the stator coil
we can simplify this process just
connect one free end
of the coils together
when the power is applied between
coils A and B
let’s note the current flow through the
it’s just like the separately energized
that’s how a BLDC
works but you might have some intriguing
doubts in your mind
how do I know which stator coils to
how do I know
when energizer so that I will get a
continuous rotation from the rotor
in a BLDC we use an electronic
for this purpose. A sensor determines the
position of the rotor
and based on this information the
controller decides
which coils to energize
most often a Hall effect sensor is used
for this purpose.
the BLDC design we have discussed so far
is known as the outrunner type. Inrunner
BLDC design
is also available in the market we hope you had a nice introduction on the working
of BLDC motors
thank you

100 Replies to “Brushless DC Motor, How it works ?”

  1. To develop maximum torque, the rotor mmf and stator mmf should be orthogonal to each other. Here as the rotor is permanent magnet the rotor mmf is straight line entering south pole and leaving north pole. Hall sensor gives feedback of rotor position which acts as input to the stator coils(inverter circuit) to produce maximum torque.

  2. Why refer to it as a BLDC? Brushless is one word and DC is Direct Current. So it's a Brush Less Direct Current…what? It should be BDCM Brushless direct Current Motor!!

  3. I’m curious. If i touched this with a magnet would it ruin the motor? I have a phone gimbal like DJI osmo that uses this tech and I think that it came in contact with a dash board phone mount magnet. It may have ruined it….but if it was that easy you would think that the gimbal would have big red warnings saying DO NOT get near a magnet since those phone mounts are everywhere and likely near these devices.

  4. Just bought a Fold N Go Folding portable power wheelchair. Now I understand how the motors on the wheels work. Awesome explanation!

  5. So is BLDC motor the same thing of a 3 phase asynchronous motor?

    The only difference is we create 3 phase with a DC current instead of take a 3 phase Alternative current.?

  6. so how come no1 wires it my 1980's way.. to feed itself.. i have a bearingless version to discuss.. i been keeping secrets.. someone else took from me & still my work was stolen few years ago on a flashdrive.. (bait to encrypt all computers but from me.. to hide my work as well as my AI BOT to link all my digital signatures.. it only responds to me.
    i am waiting for a gov to seek me out.. for all.. of us.. i refuse to share what i know with usa where i am.. cuz guilty high up.. from 1976.. still a prejudice person i personally will keep out of MY LOOP.. anyone against me.. selfish

  7. A enlarged brushless mortor would opperate many ac generators/altornators once it was brought up to speed. Three power plants in series located in the US would produce enough power to export to other nations. That is, once you successfully get one plant up to full power, you would energize the next one. And so on. Power can be tapped from any power plant or substations in between but absolutely no fusion coal natural gas solar panels will be needed once the entire series is on line. This will buy us time to develop fussion and pave the way for energy independence.

  8. You know we will probably need superconductors or semi super conductors to reduce resistance between power stations and motors. Capacitors could greatly increase efficiency. Once the entire grid is on line you could theoretically decommision your last filthy power plant.

  9. TL:DR; A brushless DC motor is in fact a permanent magnet synchronous 3 phase AC motor being driven by a DC powered VFD with a HAL effect loopback.In fact, calling a BLDC motor a DC motor is in fact a lie. The controller can be powered by either DC or AC as it is just a rectifier followed by a 3 pole H bridge. The motor itself can never run on DC.

  10. I understand this video until 3:14. What are they saying? And how does the current flow change direction when it goes through the same coil?

  11. My 8-year-old 'brushed' drill was burning out its brushes, so I got a new corded drill. Now 2 years later it is beginning to have the same problem = burning smell coming from the brushes. Now I know better and the next drill I get will be 'Brushless'. Thanks for this info!

  12. Good video but I didn't hear about maintenance or longevity issues vs. Brush motors. Are there a differences in that regard?

  13. One of the usefull and techincally it is correct video in youtube. Can you make a dynamo presentation like this on AC and DC

  14. ขอบคุณมาก
    เพิ่งจะเข้าใจการทำงานของ BL motor.

  15. __rotE==dB/dt and rotH==J+dD/dt and HrotE–ErotH==div(H*E)=power electric engine_motor ___power growth proportional speed with tension_voltage and power growth proportional not speed with intensity_amperaj ____archaix lord

  16. Good analogy with the donkey chasing the carrot. Could also use the analogy of the guy chasing the girl.

  17. Got me, got me Rollie
    (Ya can't even afford it though)
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    Gotti got it
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    Give it up
    Gotti got it
    Fuck with my day ones
    Yea you know I flooded the chain once
    Got the money and I split it with day ones
    She ain't fuck me back when I was lame, nah
    You ain't know I do my dance? (do it)
    In the club (aye), throwin' dub
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    Watch me do a hop, bust it up (up)
    I mix it up, then I hit her with the blicky, uh
    So drippy, drippy, drippy, drippy
    You ain't…

  18. Amazing. Making something more complicated by makimg it more simple. I am an electrical graduate engineer & never recommend this sort of gadgets.

  19. Technology Update: Now a days Hall Effect Sensor is not used to determine position. The New controller itself have the capability to determine.

  20. some very late info. THIS IS ANOTHER INCORRECT DESCRIPTION OF THE OPERATION OF A BLDC. problems in understanding arise, when the operation of a bldc is OVER-simplified. making matters worse, one statement is COMPLETELY WRONG. at 1:38, stator coil polarity IS NOT EVER REVERSED. the PHASES of the stator are energized, SEQUENTIALLY, with pulses of DC power, from a bldc driver/controller. (in order to be self-starting, a motor MUST have, at least three phases or three (permanent) magnetic poles. each stator phase consists of one or More coils. note that in a small brushed dc motor there are ALWAYS three coils/poles/phases in the armature/rotor.) it should be noted that, EVEN, the bldc article on wikipedia is NOT entirely correct.
    a simple bldc configuration utilizes a nine coil stator. the coils are connected into three PHASES, of three coils each. the three coils of a phase are located 120 degrees apart from one another, and are connected in series. in place of a brushed commutator, commutation is ELECTRONIC — in the form of a bldc driver/controller. also, called an electronic speed control (esc). an esc Sequentially energizes the phases, with pulsed-DC power . (this can be thought of as, 3-way, synchronized, PWM.) googletranslate

  21. Really nice video. I was worried for a while you weren't going to tell me where the current switching was done. I knew it couldn't be a dumb device with no active components. But for all I knew my understanding of motors was missing something 🙂

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  23. Contrôle moteur sans balais utilisant Arduino (بالعربية)

  24. hi can you boost this video:
    Contrôle moteur sans balais utilisant Arduino (بالعربية)

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