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The way this works (open loop) is the rotor basically snaps so that the permanent field from the magnets aligns with the generated magnetic field and in this state there is zero toque despite a high current. It is not efficient. This is simple though, and pretty stable. As you bump the motor out of alignment it naturally wants to snap back, and if you plot the torque vs angle you get a sinusoidal torque and when allowed to rotate freely it will snap to any of the points that cross zero. In a real FOC controller, the position is detected and the current in the stator is generated to always be 90 degrees ahead or behind where the rotor is. Since at these points you get the most "bang for your buck" and the most torque for the given current. Assume the controller is working, and always generates a field exactly 90 degrees. When the rotor is where it is supposed to be, the field flux vector stays at 90 degrees but the current is decreased basically to zero so the rotor does not rotate. As the rotor is displaced from where it is supposed to be according to the FOC controller, the magnitude of the flux vector is increased to provide a corrective torque and oppose the offset. A PI controller is what is often used. Another small nit-pick detail is that you are providing a VOLTAGE to the coils and not a CURRENT. The magnetic field depends on CURRENT not VOLTAGE. This can very approximately be estimated by understanding the relationship between voltage from the FOC controller, the inductance of the coils, the back EMF that works against the supplied voltage when the motor is rotating, etc. I think this problem is also solved by that same PI loop. Essentially it does technically control the voltage to the phases but due to PI loop action it is the current that is being controlled. You used SPWM. Which is OK, it is the most naive way to do it. The maximum phase-to-phase voltage (this is what matters, not phase to neutral) is limited to I think about 86% of the DC supply voltage. It is fine, but you can do better if you throw out the need for phase-neutral voltage needing to be AC sine wave centered at half the DC supply voltage and optimize by maximizing the phase-phase voltage (which does need to be sinusoidal or trapezoidal... a whole other can of worms) Finally, the long debate of PMSMs vs BLDCs and the back EMF and how they are supposed to be driven with either trapezoidal SVM or sinusoidal SVM... most motors kinda fall somewhere in between in practice so really it is never going to be a perfect match.

Nice video, but for sake of accuracy: The described method in this video is basic sinusoidal commutation. On the other hand FOC includes relatively complex current transformations, rotor flux linkage vector calculation, multiple other complex transformations and is a closed loop control scheme.

Very nice. Great explanation. I watched some videos about it before but i had not understand how this FOC worked. But now i get it. We don't need servo motors for robotics anymore.

Thank you for teaching me something new about stepper motors!

This is the best intro to FOC I have seen.. Thank you..

Thanks for code explanation, it's simple and clear as well as the code. Good job!

You can make a nice analogue clock that shows several time zones with this project. Nice video.

Muy bien explicado, como todos tus vídeos. Me he aguantado 2 anuncios para compensar 👏

To make it work in closed loop, you must consider the number of poles of the motor. I used svpwm in a 4-pole bldc motor once and got a behavior similar to yours, where the rotor is locked in specific positions. In my case, I noticed that the motor was always stuck in 4 specific positions, so I soon made the association with the number of poles of the motor. That said, I could observe that a full cycle of the svpwm was equivalent to only a quarter of the full rotation of the rotor. To solve this problem I made this consideration and the motor ran in closed loop. Consider the number of poles in your motor and do the math, one full rotation of the motor should be equivalent to the number of poles * spwm cycle.

Cool project! If you add encoder support, you could change code to create magnetic field 90 degrees from rotor magnetic field. It will apply magnetic field in Q Axis and creates much better torque and higher efficiency. Currently motor is using only D Axis, D Axis is usually used only for field weakening and it doesn't make torque.

thank you very much. I love your videos and I've learned a lot.

Thanks for such a clear demystificaion of FOC while I just sit and watch

Awesome project! Thanks! I hope you get the encoder part sorted out.

This is super nice and great video!

Great work. So as such the bldc will have a static tork as well. Just like stepper motors.

Great work! Could you make a higher current version? It would be super useful, as commercial controllers are quite expensive. This could be used with the SimpleFOC arduino library which is free and easy to use

Excellent project and very well explained

This is really very VERY awesome !

Very cool and minimalistic project! If the sensorless implementation without motor current sensing can be classified as FOC or just a sine wave inverter is questionable. But as soon as you wire up the encoder and can identify q and d axis a little better, then it's more like it

that's sooooooooo great. thanks for your best Expression

Great work!

Like a micro VFD. Sweet!

This is awesome thanks for sharing!

Excellent💯👍 explanation

You deserve 100 million sub

Amazing channel!!

Ótimo projeto

Great work

i love it very useful

THX A LOT,. already looking for..

Thanks for knowledge!

This is frickin awesome!

Brilliant bro

muchas gracias

Hello sir thanks for your information and many times i don't understand how bldc motor in gimbals and robot dogs etc get such presize angle control and speed,but now i able to understand how they work. I am from india and i am studying electronics and communication engineering in govt polytechnic and I am very much interested in electronics. Thanks for your information and teaching us in practical way and all the best for your future projects .

Very cool 😎 👌

great video

a great example. Can I change the direction of rotation of the rotor in speed mode?

Thank for the great video. Is there any benefit of using FOC over using a stepper motor?

Best video that I have seen. I was having lot of trouble understanding how this worked. This video made it clear. So you can do open loop control just by creating three PWM signals 120degrees apart. I had a question. We can do all the clarks/parks transforms to figure out how the pwm have to be modulated but what if we have a look-up-table instead with the rotor positions specifed and the pwm values for those positions so the field is always 90 degrees to the rotor? Is that a viable option?

What a phenomenal video! You have explained the full workings of an industrial servo motor. The industrial ones use a quadrature encoder but otherwise are identical

thanks nice work

That's Great 😍😍😍😍

It is príncipe gimbal great!!

Wow great

Hi I think it would be really cool if you took of the bldc rotor off, then use the field visualizer to show the actual change in real time

Great 👍

could you show us plots of the threephase voltages and currents ? idk without proper feedback for the phase currents, it is hard to maximise the quadature component of the resulting phasor sum to maximize the torque. I dont think arduino's pwm has enough resolution to create a decent enough sinusoidal phase currents. Could you tell us what is the switching frequency ? This is a good project for beginners but might have issues when you scale it up for larger applications...

Hey does any one know what a practical RPM limitation is when using the Open Loop Code "Speed Control" method? Obviously this controller is designed for slow and precise rotation which is largely why I want to use it but I am very curious to know the practical upper limit? Of course it will also depend on how many poles the motor has so maybe a more appropriate question is how many full phase changes per minute is this capable of?

Closed loop with hall sensor and with BEMF also please. Very nice explanation.

We are still waiting the closed loop. Thanks a lot it is good video

I had a question regarding the logic for the MOSFET switching so as a sine wave is applied to all 3 phases at the same time is the signal provided to the two MOSFETs for the same phase the same or inverted.

Thanks for posting a well explained video and tutorial. With the motor you have used, how do we calculate the maximum resolution of control in degrees? Ie, what would be the maximum number of steps per revolution? Thanks again and nice PCB by the way! Simon

Hello, is the L6234PD driver only used to add the radial magnet sensor ? If we don't need this option, can we ignore it ? Thank you for your video.

your video really helped me learn, I watched all your videos especially about ESC, I hope you can make a detailed explanation video about VESC - Open Source ESC from vesc benjamin vedder, I want to make something like that because if you buy it from abroad the shipping costs very expensive, I know there are other people who have explained it about vesc, I think if you explain it, it will be easier to understand, thank you

Hi electronoobs, thank you for this wonderful topic. I am curious about the black motor with hollow shaft used in the video. Can you share it's make and other relevant information? Also, I request you to add a few points for your next video on closed loop control. 1. Use the encoder in all modes, i.e. ABI, SPI and pwm. 2. Using a lookup table for sinewave generation, as the signals are repeating with an phase shift of 120 deg. This would lead to lesser computation load for microcontroller. 3. Use a smart driver like ti's DRV8353 for fault protection for larger version. 4. I have worked with AS5048A, they are somewhat prone to get damaged (I don't know how). Always keep spare. Wish you all the best for your upcoming videos.

Hey man, great video! Would it be possible to drive a 22V BLDC motor from a much higher voltage source by simply controlling the voltage going into the motor via the PWM signal? Or is this too much to ask? This would save me on having to get a VERY powerful DC to DC converter, 3kW or so... In reality I just need very high speeds, so FOC might be overkill. Thanks!

Teşekkür

I'm learning so much from your channel. I want to create a arduino robot which drives around, but the motors are too loud and annoying. So I was thinking, drone motors? but holy shit it would disintegrate into the nearest wall if they span that fast, but this actually looks like a really great way to rotate the wheels with a quiet motor with great precision. Amazing!

nice

Nice! What kind of torque are you getting from this with no gear box?

Would it be sufficient if I take an axial magnet and rotate it so the poles are parallel with the encoder? Or is the radial magnet truly required?

Ooooo. I like it.

I'm interested in this to control a car speedometer, only thing I'm not sure of is while this obviously allows for low RPM would it allow the motor to spin at high RPM? I need to be able to spin from 150-3000RPM, torque loading would be negligible. Being car based I need to be able to run from 12V supply.

hi. I would like to know if you can customize a FOC controller but with high voltage and high amperage? Thank you!

more power!!!

Saludos desde chile

Hola, Excelente proyecto. Tengo una consulta, Deseo trabajar con un motor Brushless DJI E200 - 6010, 130 Kv, los componentes utilizados en la placa que mostraste en el video, ¿Cuanto es lo maximo de voltaje y corriente que puede soportar ? ¿Podría funcionar con el motor que te comente?

Hello friend, I have a cuestion, the signal you measure in min 10:54 is in the input of the motor, or in the output of arduino? I have doubt if the driver you used also has the function of transforming the pwm signal into a real sinosoidal wave. Thank you. Great video.

Maybe the next step on from this would be a DSLR gimbal?

Is this the same technology ODrive boards use for control?

أنت الاذكى

you can make the pulse vector modulation FOC based on the open source simpleFOC group from MIT

I challenge you to make a Odrive killer, that would be over the top (even if I have to pay a dollar or two to get the design)

I'm thinking of 2804 BLDC motor. I understand that I need to supply 3 wires (phases) to it from the miniFOC driver and nothing else. My q. is : how long can these wires be? I need some 2 meters. thanx

Did yoy ever make a follow up video with closed loop?

when ordering the board Will they populate with all parts?

IDK why you need power resistors to limit current, haven't read the datasheet of your 3phase H bridge driver chip. But I have used DRV8313 in past when i was working on a gimbal. It did not require a power resistor and it is available in smaller package, and goes up to 60V VIN, I guess. Also you can check ST's STSPIN series of H bridge drivers, they come in QFN package but have low input voltage. For the board design, you can make it in a circle shape and give all the mounting holes and place the encoder right at the center and mount the PCB with some spacer depending on the clearance available between magnet and encoder, 1mm is a sweet spot, anything above 2mm will give errors/glitches in the PWM signal, this was true when I ran the tests, yours might differ.

Cool

Sir how to connect multiple MOSFET in dc to dc boost converter

Hi Andrei , thank you for making these very interesting videos. I recently watched your video on “FOC Driver Controller”. FOC is new to me but it looks like what I need for a robot project. In your video you pointed out that in V1.0 you had missed 2 connections on D9 & D10, has this now been corrected? Also I have not used PCBWAY before, I created an account on PCBWAY from your link and noticed 2 options, “Only PCB” and “PCB+Assembly”, if I opt “PCB+Assembly” and select a quantity of upto 20 it quotes $35 including shipping. This seems very cheap, what does it mean by assembly? How much of the board is populated? Do I need to add any other components when I receive the board? Thank you for a very informative video. Ernie

What is the relation between this foc controller to a stepper motor driver like the ones that are used in 3d printers? Is it the same thing?

Hi and thanks for the video! 10:08 10:48 These moments show that the rotor shaft rotates irregularly, accelerating and decelerating. What can be the reason for this?

You have something I can use with a 2 phase motor?

it looks like your encoder does work but you apply a constant torque

I WONDER HOW CAN I CONNECT MY Globisens LabDisc TO ARDUINO VIA USB CABLE? ARDUINO HAS TX AND RX PINS, LabDisc SUPPORTS UART PROTOCOL. BUT I DON'T KNOW HOW TO READ SIGNALS FROM LabDisc OUTPUT CABLE WHICH IS FOR CONNECTING TO LAPTOP. IT WOULD BE FANTASTIC IF YOU SHARE A VIDEO ABOUT IT. THANKS IN ADVANCE.

Can't this be combined with regular speed controllers so that you can have smoother motion at low speed but high torque and efficiency at higher speed?

Does this controller allow you to stop the motor at the right place?

how can you use it with mosfets?

Bro make laser light show I been wait a lot

Hi. Do you have a link to the 20(or whatever) pole motor shown at 9:17? The links to motors on your site don't have that many poles. Thanks :)

Gosh, I didn't watch this video cause I have no idea what it's about! Btw, what's foc?

I would get further away from your motor to only pick up that magnetic field from your magnet otherwise it´s possible that your hall effect sensor could pick up the motor stray fields and this could get a irregular response like you see in your video.

in future projects could you break out the ICSP pins? they aren't connected to anything and this makes the controller nigh impossible to bootload. If you have any tips on bootloading the chip, please tell me because i've found it impossible to connect anything to the tiny ICSP connections.

Make a cheetah robot and what about your multimeter eagerly waiting for video

7:04 -> not sigle one driver in your video is 3 channel...or am i wrong? i see DRV8833 , LN298N and its mini version.

is there a cheaper L6234PD alternative?

Would anyone like to share the Arduino IDE configuration that allowed them to successfully upload code, I am receiving the: programmer not responding error and have tried a couple of different Board/programmer configurations

may you please link some texts on where to read the theory on this?