Electronic Basics #18: DC & Brushless DC Motor + ESC


in the previous project I showed you how to build your own electric longboard the heart of the system consists of a so called brushless DC motor and an ESC aka in electric speed controller such setups can also be found when you want to build a quadrocopter or for example inside your DVD drive or your hard disk so in this video let’s find out how those motors and ECS work together and what you should be aware of if you want to build a project around them let’s get started first of all let’s have a look at a similar motor type to get a basic understanding of what is going on DC motors like the name implies use direct current in either polarity to create a rotary movement but since looking at them from the outside pretty much explains nothing I used my rotary tool with a cutting wheel to firstly open up the back and afterwards remove the front gear in order to take the whole construction apart inside the metal case we can see two permanent magnets with opposing polarity also known as the stator because they stay in place the rotating parts that are removed is called a rotor and consists in this case of five coils that are connected to commutator which is divided in five equal parts to keep it a bit simpler though I reduced number of coils and commutator parts to only two in this diagram the last remaining components of this motor are two carbon brushes which connect our DC voltage to the commutator and thus the coils now if I apply a voltage current starts flowing through them which creates an opposing magnetic fields since they are connected in series and have a reverse winding direction the results are then obvious the same magnetic polarity creates a force that pushed the coils away why the other side of the stator attracts them but just before reaching the final position the carbon brushes reach the other half of the commutator and reverse the magnetic polarity of the coils which get pushed away again and then again and so on and just like that the rotation is created brushless motors use a similar principle but on the other hand change a couple of things around to make it more appealing for certain applications again let’s firstly have a look inside this piece motor in order to find out how it functions this time the rotor consists of four permanent magnets with alternating opposing polarities and this data consists of twelve coils which utilize the metal case as a heatsink to improve the lifespan but to keep it simple once again let’s use one magnets with six coils in this diagram the three coil powers which are also connected in series and will be reverse winding direction are bound together through star connection which is not a surprise because the label of my motor already said so now we need to energize two coil pairs one after the other in these six steps to create a complete rotation of the rotor while the DC motor used the mechanical principle of a commutator to create a rotating fields the brushless motor uses an electrical one also called the ESC you can get different variations with for example software to program them and all kinds of different features but in the end they all do the same minimum by applying a control voltage to the inputs aka the yellow wire I can set two reference points which are basically adjusted for length of a voltage burst in order to adjust the frequency in which six steps for one complete rotation repeats obviously a higher frequency means less time for one rotation and thus a higher rpm the three states of the outputs are higher low and floating which is realized through an array of p-channel and n-channel MOSFETs the number of parallel MOSFETs for one outputs in this case six of them directly determines how much current your driver can handle more thumb means more current and thus your motor can be more powerful but the price also increases and the overall current draw is also determined by the loads which is attached to the shaft the amount of voltage applied to the ECU and also regulated by a pulse width modulation of the different output states okay getting back to the practical example if I set a constant frequency year of around 65 Hertz I can use my Tacoma door to measure an RPM of around 1740 if I divide that by 60 year I get a frequency of only half the original one but why the reason is the double number of coils and especially the permanent magnets which cause lower rpm but on the other hand a bigger torque that is also the reason why outrunner brushless motors are preferred when high torsional moments are necessary you tumor space on the outside they simply can accommodate a higher amount of magnets and thus like I already said they can achieve lower rpm and a higher torque at the same frequency at the ends let’s talk about the KB rating which stands for rpm per balls up lights let’s use a 7 point 4 and 11 point 1 volt battery as an example with the 520 kV motor I reached the maximum rpm of three thousand seven hundred fifty and 5644 why would the 920 kV 1 I reached a maximum of six thousand seven hundred eighty and ten thousand five hundred so it is true that with higher K B rating you get more rpm and by calculating with the ratings we get values which are definitely close enough to reality but in the end it’s not mainly about the voltage which determines the rotation speeds it’s about a higher frequency of the year see that can be achieved with a higher voltage and depends on the characteristic properties of the motor and with that being said you already know quite a bit about brushless motors and the ESC if you liked this video don’t forget to give it a thumbs up consider supporting me through my patreon campaign in order to keep such videos coming stay creative and I will see you next time

100 thoughts on “Electronic Basics #18: DC & Brushless DC Motor + ESC

  1. you say 'series' but it sounds like 'serious'😂 btw …your videos are better than awesome! and i am your Indian Subscriber!

  2. great video bro,quick question would stacking mosfets on my ESC work to make it more resistant to burning and would it make the motor stronger?thank yoy

  3. Can you help me? If I had a motor like the EMAX GT5335/08. I would need to buy a esc with approximately 90 ampers. And the number of cells that the esc need to handle would be 10. Right?

    Specifications of the motor:
    http://www.hobbypartz.com/66p-190-gt5335-10-kv200.html

  4. Hey .I have a question .If i use a laptop charger 12 v direct to DC motor(`12 V ) will work ? ………or will burn .Ty for the answer.

  5. help! my brushless motor, is clicking and not providing power, i was going at a reasonable speed, then ejected from board. holding it upsidedown it only clicks and rocks back and forth when power is applied =/

  6. I want to replace the MOSFETs in my mamba phoenix rated for 50v 160a continuous. I need an ESC that can output 30v at 400a. I was wondering how feasible it would be to Replace each MOSFET with ones that can handle 30v (instead of 50).
    another thing I saw online were stacking MOSFETs on top of each other…. i already made an enormous cap pack using 6 35v 4700f (in parallel) so replacing the MOSFETs looks like it would be harder than stacking an extra one right on top.. oh and I'm going to use 2 larger cooling fans along with the stock heatsink. any suggestions?…. my brush less motor is rated for 25v 350a continuous; something like 7200w. (200km/h+ 1/8 rc car)

  7. Your videos are superb 🙂 No academese ("the flux cutting is propprtional to the cross product of the lagrangian transformation which as will be obvious on inspection is the second order differential equation of mah butt"), engaging style which is fun to listen to, and obviously a huge amount of knowledge behind it all 🙂

  8. GreatScott, your video is being uploaded by other people. here is one: https://youtu.be/eCR5M2KKVyc

  9. Can you explain what you are doing with the joystick around the @3:50 part of the video? I know that joysticks like that use 2 or more potentiometers and I've played with one in that capacity by hooking it up to a home made speaker as well as a simple led circuit, but the resistance was far too high for either of those circuits so it mostly served as an on/off switch…

  10. HELLO, I have a problem with my esc, when i connect my esc motor battery there is no think done but when i deconect the midle wire about the esc i heard some beep then no think doing, this problem made when i make a mistake connecting the wires, the bec is good it s make 5v, please should you give me some advice to resolve this probleme, thanks

  11. is there a way to make a setup to both test the motors and the ESC's of quadcopters? what would be the best way? what would be the cheapest way?

    Great content

  12. can you make a small winch with the brushless motor and a pulley system with it i think it would be a cool video if you lift some weights with the motor

  13. Hi everyone, I need to drive a brushless 2204 motor with a kind of potentiometer? I don't need a thing like show in the video at 3:50. I already have a power supply + brushless motor + esc. Then is there a place where I can buy card with included potentiometer to control everything? Thank you very much for your help.

  14. Scott your videos are very nicely done and a very good learning platform. May I com with a suggestion that you make your videos longer but with the exact same content so you don't just rush through things that no one have the time to snap up(understand) ? I love your channel but thats my only problem and it's is a big problem that makes your content much less interesting but it really is not. Please can you do that? Why the rush?!!

  15. i have a dc motor ~3,5cm drameter and 5cm long, i would like to power with my lab bench ( pc psu ) but while i connect the +12 and GND the psu spops (same stopping when i connect the +and gnd to a same conductor (i think its name "short circuit" in english , what is tze problem ? and how can fix ?

  16. hey I Know this is dumb and will destroy my motor and gears. but i got a rc car with a 390 brushed motor. that motor can pull my sister (65lbs) on a skateboard
    but i Want to upgade the motor so it can push me(127lbs)
    what kind of motor shall i look after ? is the t (turns) in the motor importen
    is it the torqe thats importen or the rpm or shall i go for a brushless setup?

  17. Silly question but if I wanted to learn about all things electronic should I pursue an electrical engineer degree? or are there other pathways?

  18. What happens when the motor are spinning without power from the esc? Can the esc handle the current coming from the motor?

  19. Hey why do you not used the beast motor for your longboard because it has a ideal kv rating and 6000watts would be great for hills

  20. Im a little confused.
    So its a star winding with a centre tapping…
    Where do you connect the positive and the negative current feed?
    and where does the yellow control wire for the windings connect?

  21. Hi! Amazing channel 😀 . i was trying to figure out a way to realize a moving system for a kayak. I was thinking to power a generator with pedals and wire it (they would be hard to mechanically connect to each other)to a motor. is this possible? Would it be cost efficient considering that you can buy a motor for around 140 euros? It would be funny for sure!

  22. Can you make DC genrater with brush less moter if yes, so what the winding is it? I have many brush less moter and trying to made genrater and also looking on internet but I didn't find any thing and then I remember you can help me. So plz help me I am waiting for your help you are my last hope

  23. Your speed calculation for the switching frequency, depends on the pole pairs.

    Calculation: electrical angle / pole pair = mechanical angle

    Your big PMSM has 4 poles (N+S, N+S) so 2 pole pairs therefore the factor ~ 2

    The small motor, PMSM has 7 pole pairs so 14 magnets inside, right ? 😉

    The fact with the KV story is correct!

  24. Hi friend can you make the video on how to make the ESC in home to general electronic components please make the video of ESC please friend

  25. What kind of bench power supply would be appropriate for running a bunch of BLDC motors? Like 81 motors each rated for a max 10amp with 30amp esc… I have a project I want to try building but I would rather not use batteries since this is a stationary project that would be used intermittently.

  26. Question ! What kind of motor should I use if I need 300 RPM with a 7.4 LiPo ( 2400mAh, C rating 35 ) battery ? All motors seem to have a very high kV rating !

  27. Very good video I always take time to watch them is a very good information thank u for keeping us informed sometimes i forget and I watch the videos and I keep going on with my projects.

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