Make your own ESC || BLDC Motor Driver (Part 2) 

There shall come a day, where I will understand 100% of the content you post. But today is not that day!

Many people claim that your videos are too complicated but I think that its the way to go. Well... Nobody thaught me about eletronics. I am learning because I want. The thing is that even if the subject requieres knowledge I will try to learn the "basics" and then come back to your videos. I think people should do that. A big part of what I know about eletronics comes from you, because I feel motivated to learn more and more so I can understand better the videos.You are a genius GreatScott! Keep this solid work. You inspired me and a lot of others. Thanks for the effort!

I am VERY glad that I found your videos. I'm building an vacuum cleaner robot and need to build simple, but powerful ESC. Now I finally understood how to do it. Brilliant!!!

Did not understand anything, but still watched because hypnotized when GreatScott! is drawing his schematics ... Just marvellous !

You can use hardware comparator that is in Arduino, at least for BEMF - you can attach virtual ground to AIN0 and phases to 3 analog pins and use internal multiplexer to choose which pin to use. It is much simpler and less error prone (PCINT aren't best solution for time-dependent tasks, and driving BLDC is such) than using external comparator. The only thing you have to have in mind is voltage levels, but simple voltage dividers should do the trick. Also you have to have in mind, that drone BLDS can operate at hundreds of amps, not like your small chip can deliver - 4A. Please tak that into consideration when selecting proper MOSFETs in the end of video.

I am not sure if any one else has mentioned it, firstly appart form a very good tutorial, you are only running the motor in synchronous mode. Like a stepper motor, to get more speed you need to increase the frequency. It is not true brushless where the ESC only performs commutation as dictated by motor position and in such a way speed is governed by the voltage applied and the KV rating of the motor. Most ESC's start in stepper motor mode but as soon as the BEMF is sufficient to detect commutation state they switch over to full brushless, which is more efficient. and allows for faster operation. Thank you.

I absolutely love your videos! You have inspired me to learn more about electronic engineering and making something amazing. Keep up the great work!

I LOVE that you show the troubleshooting process.

I guess I should add my own comment. First, I just want to say this is a FANTASTIC video and I hope to see more. I dearly wish the people saying stupid things like "duh... just buy a ESC" would understand that the point is to learn and develop new ways of doing things, as well as to understand why ESC's work the way they do. So... Let me be sure I understand: 1. You have to start "open loop" as far as position goes because you don't know where the motor shaft is... you just pulse it and switch the power back off when the voltage rises in the coil. You switch to the next coil after a set time. This is slow, because the A2D takes time, and the speed is pretty much just controlled by the frequency of the coil switches, not by the voltage applied, because you can't apply any more voltage without frying to motor. This is a "stepper mode". It should have good /holding/ torque, but the phases are too far apart to have anything like reasonable /detent/ or "pull in" torque like a regular stepper. The fact that you don't know where you are doesn't really matter because you can't drive the motor any harder anyway... if it's "skipping steps" against a load... oh well. 2. Once the speed is high enough for the magnet to induce a detectable back EMF voltage in the the third / undriven phase, we can use a comparator to trigger on that as our signal to switch to the next phase. At this point, the speed of the motor is controlled by the voltage we apply to the driven coils. As we back off the voltage, the motor moves less quickly to the next phase, and the back EMF spike appears later so we switch slower. Or we apply MORE voltage, not bothering to sense the voltage buildup in the driven coil because we know it won't get high enough to fry the coil or to pull more current than we can provide because it won't have time. The back EMF pulse happens quicker, we switch faster, and so the frequency and speed increase. 3. At some point, we probably can't sense the back EMF pulse quickly enough and we go into another open loop mode where we are just hitting the coils with everything we have and switching based on what we think the motor needs. If we start seeing the back EMF pulses again, then we can switch out of this mode and back down to mode 2. Or perhaps we still see the EMF pulses, but we must switch /before/ they appear. We are only looking for them as confirmation that the motor "caught up" with us. If we wait for the pulse, it's already too late to switch to the next coil. If we go ahead and switch, and the pulse doesn't show up when we expect it, then the load on the motor is too great and we have to slow our switching down a bit to avoid falling out of phase. I'm not sure this mode is actually necessary, but I think it may be why you are unable to get faster speeds. All of that could be avoided if there was an encoder on the motor. In that case, we could simply pulse the coil that matched the current position of the shaft to get started, we could always know when the motor was ready for the next phase, and we would never lose the back EMF pulse as we ran slower or faster. I'm really interested in the use of BLDC motors to make servos. I have a good encoder and some programming skills, so I hope to develop some ideas in this space soon. In the mean time, if you want a fun encoder to play with let me know. They are magnetic, non-contact, and still support very high speeds (28K to 75K RPM) and resolutions (4000 to 360 clicks) and... have a digital mode where you can just read out the current position instead of having to count the encoder pulses. In any case, I'm completely fascinated! The use of the back EMF pulse is such a cool hack and seeing all the complexity of it from your exploration really helps me understand the limitations of this system. THANK YOU!

Excellent pair of videos! This was exactly at my comprehension level, and I think your pacing was spot on. Neither boring, nor too advanced/fast.

Love it "...instead of the measuring bullsh!t" at 5:30. Finding a way forward is what engineering is all about!!

I like that you took this problem from the very roots, but with better and smarter ic you can control in a much simpler way and more attractive for your viewers.

This video has saved me! I didn't understand why my motor didn't run continuously, and at last I found this video that is the only on youtube which explain why! Thanks a lot

These two videos were fantastic, even if I'm 4 years late saying so. Thank you for your hard work!

Hi Scott, thank you for your inspiring videos. This video has remind me two salvaged washing machine motors that I would like to use for something useful. A video series on speed control for this universal motors would be really great, if made it by you. (and I bet would be pretty interesting for all us beginner makers that want to build some useful tools). Thanks again for your videos, I really appreciate it.

IDK if anyone pointed this out yet, but... the ATMEGA328P in the Arduino Nano has an internal comparator between PD6 and PD7 that can request an interrupt whenever the positive input of the comparator is greater than the negative input. Plus, as far as i know, runs asynchronously (correct me on that one, if needed). This means that you could actually measure the current flow using the internal comparator without worrying of it not being detected AND you actually removed a chunk of circuit from your board In fact, the IC in the ESC is (usually) an ATMEGA8 and you can see they use no extra ICs, which is rather impressive, i must say

Hi, Scott! I love your videos! I really want you to make a sensored version, too! With IR2103 drivers and a hoverboard-like motor

Beautiful videos, you pay attention to every small detail. I like those close-ups where you are writting

Very well made video, thanks for sharing the steps you went through, and pointing out how hard it actually is to make a good ESC.

Hey all! If anyone is thinking about building this, this circuit needs an additional resistor network! I just made something quite like this, using the same LM393 comparators, and my timing was looking really strange, and the speed/torque was a bit lacking. I'm using dual source, common ground to power my circuit, and the motor voltage is around 11v, the rest is at 5v. The motor acts as a voltage divider, making the motor common and coil leads around 5.5v, so what was happening was when the motor started to spin fast, the comparator inputs would get saturated over VCC and on the way back down take a fair bit longer to switch low, making the next step happen much later than it should. I added a resistor network (10k) at the coil sense leads to half the voltage, and then connected the common with 1ks. Now my voltage sits in a happy place between VCC and ground, and the timing is looking spot on. Have fun!

I keep coming back to your videos to see If things you say are starting making sense to me, If they do, then I know I've improved

I made a DIY arduino from scratch but this is like a next level! Great job!

Thanks for making these videos. I love keeping up with your projects. I hope your studies are going well!

This man can distroy esc business

What I'd love to see is an open source esc project for retrofitting brushless motors into electric cars. I think this would really beat the price down making more people give it a go.

Your method to build ESC is combination of reading the schematic + try and error. You not know everything but you believe it is not difficult to achieve what you want. Now I can see your leadership.

As an R/C amateur, I thought I'd drop by this vid and learn how the ESC on my cars works, but now I feel I need an electronics degree and possibly maths as well

My god, I think u can see the electrons flowing through the wires. I am learning so much from you. God give u a long long life so that you continue to upload such videos. A request. Pl, do make the videos a bit more explanatory for ordinary mortals like me........

Danke,I love your videos. Even though I don't yet use Adrino and I am working on improving my off-grid solar system,I always come across at least 1 of your videos (which are very helpful in my search).

Scott, I think I may have found an error in your explanation or I don't quite understand it. At 0:56 you show how you activate the corresponding low-side FET to short the coil with itself, reducing the current flow. If A-HI was high and turned off at threshold value, switching it off makes sense because it stops the current flow. However, opening A-LO makes no sense in that case because the current would be allowed to flow in the direction you've drawn anyway, because of the body diode of the MOSFET. It seems to me that, instead of what you were explaining there, you would like to switch the high-side MOSFET at threshold value, and switch it on again once the waiting time has passed, and leaving the opposite FET on to allow current to flow. Activating the corresponding FET does not make a difference (because of the body diode), and disabling the opposing FET could create a spike in voltage that could kill your FET (I do think the body diode of the opposing high-side FET allows this to dissipate but if not, breakdown voltage is easily achieved). However, maybe I didn't understand your explanation right. Could you give me an explanation on this matter?

Great example. Really enjoy this channel. The example code on the instructables has a few issues like video says but its a great learning tool. First time Ive used 3 interrupts simultaneously!

What just happened. Not into programming and after watching this I now know why. Do like your videos though, keep them coming.

Great Video !!! Comparators bounce like a button causing many interrupts in zero crossing areas, i couldn't find a stable solution for that. Ps. Please use something plastic while showing oscilloscope screen, screwdriver will scratch it.

the only useful channel on RU-vid

9:28 man I hate this sentece :(

anything compiled in the arduino ide will be useless for high speed real time reactions like this, it produces stuttering bloatware MS would be proud of, hand coded would be so much more efficient, and so much more complicated. What you have achieved here is simply amazing

things like current limiting and BEMF feedback had been recurring problems in my hand-made motor drivers. I had tried doing BEMF sensing/... via discrete transistors (ex: 2n3904) but with limited success (don't have opamps or trimpots; mostly tried biasing things via voltage dividers). recently put this on hold as this stuff eats a lot of money and components (more so when accidentally blowing up comparably expensive MOSFETs and similar). I had admittedly had more success for some stuff basically just using stepper motors and computed duty-cycles and speeds. for fastest speeds with steppers, generally had best results with both phases active at a time and using a variation of reverse-sawtooth waves (square was better for torque but limited to low speed, sine wave made motors run quieter and cooler, but had neither great speed nor strong torque). in code, could switch between driving waveform and duty cycle values and similar based on target speed (except on some MSP430s I was using, where the drivers were pretty limited due to the 2kB ROM size limit).

Considdering that most quadcopter esc's are 12A or more each, and your build will weigh much more than most racing quads then i would suggest that you beef it up to handle atleast 12A if you want to have some power left to save yourself from a hard crash. Most of the times my quads have been broken were when i didn't have enough lift to pull myself out of a bad situation.

Great video! Being a motor control enthusiast everything made sense to me and I would love to make it myself when I have the available resources. Thanks!

Sehr informativ. Der iterative Entwicklungsprozess rund um die Problemchen hat mir gut gefallen.

I liked the way he used 3 resistors to produce a virtual earth when there was no access to the centre of the windings. Lateral thinking,

Hi, can i ask if this code is correct? You use only "PCMSK0 |= (1

Cool project! I watched the video several times to understand how to control a BLDC motor. I always confused ist with a synchronus motor which needs three sine waves. But i'll use an other microcontroller. I don't really like Arduino because the most people never reads datasheets or know how a microcontroller works. They simply use all the libraries without understanding what's happening. I'll use a PIC18F4431 microcontroller that has a special hardware to control BLDC motors, with integrated timer for the rotation frequency and another one for the PWM.

Wow, you did some great work with the MCU timings. You may need a FPGA or CPLD to meet tighter timing constraints, but maybe the FETs will be enough for this. It will be interesting to see this project take off.

Great job, not easy to make that motor spin. A lot going on. I don't where you find the time to do all this while working on your advanced degree. Your going to be an excellent engineer.

German engineering in action!!!! Fair play to you!!! I wont be building an ESC but really enjoyed the videos

Since you can use the comparators to form a state machine to drive the current flow around the motor, why not try creating an analog controller? You could use a 555 to generate a signal in response to the potentiometer, then use the comparator feedback to drive the excitation logic. The single .2v comparator can also be used to drive the current chopper, since clearly it was the Arduino code that was at fault and not the comparator.

I am building an electric ATV for a competition in which I would use a 48V BLDC motor having Max RPM of 3000. I want to know should I buy a commercial IC or make my own!

Excellent presentation. Keep up your research work. Zero crossing is the solution as you set in your last version. Liked your video.

Finally,the weather is decent and i can build some LED Blinker circuits in my garden.Lg from Bayern

Best video ever. "Screw the measuring technic" haha! Controlling n Using closed loops systems it's sometimes a big headache. Thank you I've learned a lot about Controlling these kind of motors you really love the subject and share it with us. Greetings from Ecuador.

Never can miss a video of yours

@5:03 "And that was the moment I said Screw Measuring, I'm going to us an additional timer." Freaking brilliant! =)

this is to save power , control speed and increase efficiency right. More motors could be used because you are like trying to run on low load right. Is this a big delta configuration or no it is star. In a series i dont know much of elecric motors i love the video its very good.

the inability to achieve high RPM also comes from the limitations from MCU. To achieve high rpm, Phase Advance method is used. Microchip has a nice application note on sensorless control

Really fantastic work, man!

"And that's a subject for another video!" this means the tutorial will come up soon (2022)😉

Sir what level of knowledge 😲

This is great. I would love to see more about getting your custom ESC closer, or even superior to the commercial one.

Oh my god, I'm really excited for Part3, keep it up the good work man!!!

This was a really interesting pair of videos. Great job explaining everything. I'd be interested in a high power high voltage ESC design for E-bikes or similar

Question : why didn't you use the integrated analog comparator of the Atmega328p ? Its non-inverting input is on AN0 and its inverting input can be muxed on-the-fly on ADC[0..7]... ( cf datasheet chapter 23, page 234 ). In fact, this trick is used on any atmega8-based commercial BLESC. ;) AN0 gets the summed phases voltage, and negative inputs are switched on each cycle.

Great video as always! I'm wondering if you could use the signal from the virtual ground point directly with only one comparator instead of 3 separate pins? I have used that star point to time a current source BJT, but I have no idea if this would work with Arduino. Any thoughts?

I tried to make esc with my L298 before. and it's totally garbage if you compare to commercial one. Especially I'm stuck at my motor spin at highest speed and do the loop. by your explanation maybe I shouldn't try to make my own esc any more cuz it's doesn't save*(cost) something .

Awesome project! We made it exacatly like you.. The only problem is that the motor isn't spinning fast enough. Do you have any idea why this is happening? We using the software 4.ino

Great Scott, I think you might want to to consider lighter motors and a different structural material, considering wood has a high wind resistance therefore require more thrust

you are the best (y) , because you know about electronics - analysis - and programming

@9:28 Is it time for that video, yet? Really interested in utilizing reverse as well as seeing what kind of power is possible with these mystical new components.

sir, here in India , there are many BLDC motors of Electric scooter not working anymore because their controllers were all China made and now that controllers are not available in Indian market, so what to do to use motors again in electric scooter??

I have seen some of the comments below, I am curious what are the individual components that make up for a good ESC. Some of the ESC are so small based on the current rating of the motor being driven, I would assume that most ESC use the same components with beefier mosfets for larger motors. So does a commercial ESC use a micro? Or is it purely analog? or both?

Best part of the week when Great Scott! uploads

>>> made own 3 phase controller from osc ( 74hc14 / 555 ) 74hc393 ,74hc138 74hc30 - 2n7000 - got plenty of these if it 'blows' - not a problem

Been waiting for this the whole week! Great videos man!!

Why did you go with 3 comparators on each phase output as opposed to just one on the input to the L6234 if your only looking to limit the current?

Great video, as always. I hope to see a future video where you develop a more powerful board!

0:50 - If the motor is spinning and two coils are shorted, doesn't that impose a braking moment on the motor, which would counter its acceleration?

Useful project, let me learn more and more and this is the most important thing.

The man is a genius !

If a motor is rated 30A max, does the ESC also need to have a 30A max rating? What if I run it with a 20A max ESC? Will the motor just have less torque, or will it not work at all?

@phu cao Peak current are momentary and they don't damage the devices till you reach maximum peak current rating and every power device has peak and continuous ratings.

I want to make BLDC controller for self balancing scooter, what changes should be done in this circuit?

That's why I just get ESCs off the shelf, very interesting try on your part though.

HI, I have followed your video and information on Instructables to make a circuit using the 4th code you posted, and my motor is struggle to rotate. It is very choppy and seems only using the timer instead of the BEMF to rotate. I have check my circuit to make sure is correct, could you please suggest why I am having this problem?

Thank you. What is ESC or BLDC? what measuring equipment do you use We seen some for half of a second.

How can I convert a DC signal/output that would normally go to a DC motor, to a useable signal for a esc for a brushless motor? Dumbed down for some one like me.

I made very basic raspberry pi ESC with python. This video solve my problem that motor get stuck when it is in high speed.

I love this video. Did you have to use the comparators because the arduino couldn’t sample quick enough?

Hi Scott!, Very informational video. Could you please make a video explaining how to make an ESC using MOSFET's and MOSFET drivers instead of L6234 IC? L6234 is great but the DIP version of it is no longer manufactured and the peak current of the IC is also kind of low.

The Arduino was unable to handle the very short time interval. What microcontroller is used in the commercial ESC. Is it a 32bit AVR type running at a high clock speed.

GreatScott, can you offer any advice? I have an application that needs to rotate a shaft at 15 RPS (900 RPM). As the speed is fixed, are there any gotchas if I simply supply the 3 phases to a BLDC from a uController (via FETs, of course), and start out slowly and simply accelerate it up to speed without any speed feedback - simply run the BLDC as a synchronous motor? I have watched and read a number of accounts of ESC designs, and a number of people have commented that it was a long project with lots of pitfalls along the way. Software is always a problem, especially if it has to handle setup of the various modes, but would you say there's any difficulty in getting the hardware working? It looks quite straight-forward (is that naive?)

Hi! Does your driver IC implement a lock time between high and low side? Because that can cause a hot path and also a high current which means heating the driver circuit and the motor up. Eventually it will be destroyed.

Hello sir, I am trying to do this project with L6234D SIP package and 1000Kv BLDC motor. I am using adaptor of 12v and 2 A for power supply. At the end motor is only give magnetic vibration but not able to rotate. I don't know why it happens, please give some guidance.

Why don't use arrays for the states, instead of switch with functions?

Warum lässt du ihn nicht mit einem konstanten drehfeld für den startvorgang laufen wie einen normalen synchronmotor um in in Bewegung zu setzten und gehst dann ist die normale Laufroutine zurück?

I wonder about zero-crossing circuit which you use op-amp to compare between virtual neutron and BEMF from each phase so the question is why BEMF go to Capacitor and pass through resistor ? Is it wrong? I think It look like low pass filter but wrong resistor position .

According to the datasheet of ATmega328/328p maximum ADC sample rate is 15000 samples/sec at 10bit resolution. Minimum time required for 8bit ADC is 13us and 260us for 10bit. So, how did you actually measured the A/D conversion time??

Great video waiting for part 3 👍

Instead of shorting the coil to ground, couldnt you just use a mosfet driver with an enable pin or individual FET control (non-complementary), so the coil floats by just turning off all FETs? shorting it wastes energy (since your braking with the motor when shorting the coils by converting the back EMF to heat and thereby taking energy out of the system.

with the slow rotation speed you think it is possible to make a motorized gimbal with that esc?

waiting for that more powerful ESC that you were talking about at the end of the video.