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Spining BLDC(Gimbal) motors at super slooooooow speeds with Arduino and L6234

First of all You won’t find here any information on high speed BLDC motor driving. For that purpose You need to know rotor’s position, so You have to measure back-EMF or use Hall sensors (not needed here).

For basic info about driving BLDC motors here is best “classic” articles on internets:
Driving a three-phase brushless DC motor with Arduino – Part 1. Theory

Driving a three-phase brushless DC motor with Arduino – Part 2. Circuit and Software

http://www.instructables.com/id/BLDC-Motor-Control-with-Arduino-salvaged-HD-motor/

I used specialized triple half bridge IC L6234 (~ 8$). You can make the same spending less money (but more time) with MOSFET transistors or other IC.

But be careful, I found a lot of cases in various forums, where people burned their Arduinos or L6234 chips.

Magic Blue Smoke Attention

ATTENTION
If You connect L6234 INputs directly to Arduino and OUTputs to low impedance motor – current from Arduino pins will be driven directly through L6234 to the windings and to the ground (without external Vs power applied to L6234). This makes very good chance to burn Your lovely microprocessor.
Also in application note, one sentence is worth to mention – “To avoid overload of the logic INPUTS and ENABLES, voltage should be applied to Vs prior to the logic signal inputs.”

I also very recommend to study (or/and purchase) this open hardware driver board based on L6234 BLDC Motor Driver by Michael Anton. It has input protecting resistors, zeners, power supply/filtering components and even back-EMF sensing circuit with amplifier (not used here).


L6234 datasheet is surprisingly useless. Go straight to Application Note AN1088 instead.

My setup of Arduino and DIY driver-board:

P1090837a

I added current limiting resistors (1kΩ) to all INputs and ENable pins, a bunch of capacitors recommended in application note and current sensing shunt resistor 0.6Ω (big blue one).

There is main illustration, for basic BLDC driving using 6 step sequence(rectangular current):

6 step BLDC driving sequence
It works very well on high speeds. But on slow RPM’s You will have choppy steps. So we need to smooth out driving current to sine waves:
 six steps BLDC to sine wave

To achieve this, You simply set ENable pins to HIGH (as except few zero moments, voltage is continously changing). And feed the sine-wave modulated PWM (SPWM) to INput pins:
SPWM

I didn’t tried to force Arduino to make sine calculations. Lookup tables was used instead. Here is a link to OpenOffice spreadsheet:
openoffice_calc BLDC_SPWM_Lookup_tables
You can generate traditional sine waves (SPWM) and Space-Vector PWMs (SVPWM). Try both and decide which to choose for Yourself.

And here is actual Arduino code, fused from different sources:

After compilation You will have info that there are still plenty of memory. Even after heavy 360 values sine array.

So, there are 360 “steps” in one electrical revolution, and tested motor had 6 electrical revolutions, per one mechanical. This means 360×6 = 2160 “steps” per mechanical revolution or 0,16(7) degree of precision. If not enough, You can make even 3x more precise lookup table.

Here is some video illustrating results (You have to be very patient to notice movement on last one! )

SVPWM modulation is used in this video. Pot interactively changes delay(); value.

Support

If I helped You, please help me. Thank You!

  • 51 Comments
    1. Salvador Hurtado April 20, 2015 at 21:22

      Thanks a lot, great easy code and perfect explanation. Help me a lot with my robot project.

      Your sketch go perfect with a ST-L298 motor driver and a Turnigy gimbal motor.

      😉

      • Jason Lee May 23, 2015 at 18:27

        I almost copied this program to generate SPWM using STM32,along with a DRV8313 in the hope for driving a 3-phase BLDC,would you please help me?
        My e-mail address is 827366470@qq.com

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    6. A/P Daniel F. Larrosa April 21, 2015 at 08:22

      Nice work ! It has appeared also in Hackaday.com

      http://hackaday.com/2015/04/20/driving-a-brushless-dc-motor-sloooooooowly/

      Thanks !

    7. Moritz April 21, 2015 at 09:37

      Pretty cool job! Thanks for sharing!

      Since I don’t have much of an electrical engineering background I wonder What exactly are the limitations of this compared to a “real” stepper motor. I imagine that the torque is probably pretty low…? Are there any other drawbacks?

    8. Pingback: Spining BLDC motors at super Slow speeds with Arduino and L6234 - Arduino collector blog

    9. John April 21, 2015 at 14:59

      Hallo! Great job!
      Please tell us about motor torque!

    10. Niko April 22, 2015 at 15:41

      Nice job

      Can you publish or send a diagram of the circuit?

      Thank you

      • Lalit January 7, 2018 at 04:41

        I need the circuit diagram as well
        Please share with us

    11. blipton April 22, 2015 at 17:31

      I’ve got a motor that doesn’t have any hall sensors, so this looks perfect!

      But does it matter which of the 2 switches the pwm is on? For example to adjust the speed, do you change the duty cycle on the high side phase switch, or on the switch connected to the low side? With respect to pwm, I’ve seen references to ‘unipolar’, ‘bipolar’, ‘complimentary’, ‘1-4 quadrant’, but I’m not sure if/how it’s related.

      Does anyone know if assembled boards are available for purchase? I saw another bldc driver, but no assembled boards either (https://github.com/lgbeno/BLDC-Booster http://open-bldc.org/wiki/Open-BLDC)

      • Michael Anton October 15, 2015 at 00:12

        I just recently sold a few of these boards, and I would consider doing another run if there was interest. Send me a message.

      • Michael Anton February 22, 2016 at 01:06

        I often have assembled boards available on my Tindie store. I’m out of stock just now, but I have another assembly run in process, so they should be in stock soon.

      • Michael Anton July 28, 2016 at 09:29

        Yes, I have some assembled boards available on Tindie for purchase. See my website at http://manton.ca for details.

      • Michael Anton October 22, 2016 at 23:20

        Yes, I have assembled boards available in my webstore at: https://www.tindie.com/stores/manton/.

    12. Serlo April 24, 2015 at 00:47

      Good job

      Can U post the circuit diagram???

    13. Mark April 27, 2015 at 23:47

      I would love to see what your wiring diagram looks like

    14. roberto May 11, 2015 at 06:56

      Hi there, thank you so much for info..but if there to make change if my motor is delta connection inside?

      and mind to share the circuit diagram?or u directly use as shown in AN1088 datasheet?

      thank you.

    15. Yasin Kaya May 15, 2015 at 12:26

      Thanks for perfect explanation.

    16. Yasin Kaya May 16, 2015 at 14:11

      I have some overheating problems while using this control technique. Is there anyone has same or any solition recommendation?

      • abc July 21, 2015 at 22:33

        I recommend external cooler or blower.

      • Owen White March 11, 2017 at 18:40

        Yes. One issue is you want to use a gimbal brushless motor. These motors are specifically designed for slow speeds – I believe the trick is they are wound with more wire so they have higher resistance and do not get as hot. The other thing is you can basically change the power delivered to the motor by reducing the PWM frequencies in berryjam’s sine wave array. I created an implementation of this here:

        https://raw.githubusercontent.com/owhite/brushless_gimbal_motor/master/simple/simple.ino

        Note, that code is used for a particular motor driver board so the pins are hardwired.

    17. Bill July 26, 2015 at 12:34

      How much torque am i likely to get out of the motor when running at these low speeds. I have an application for such a drive system but I do need torque and was trying to avoid using a gearbox if I can.
      Bill

    18. Steve_LS August 22, 2015 at 08:15

      This one is called open-loop v/f control. You apply sin voltage to generate sin current so that the motor can rotate at very low speed depending on the sin frequency. However, the problem of this method is that the applied current may not be at the correct phase. Torque = ea*ia + eb*ib + ec*ic. Suppose e and i are both sin with a phase difference of theta, Torque = 1.5EIcos(theta). You can easily see if theta is big, you need very high current to realize the torque to rotate. I think that’s where the heat problem would occur.

    19. Michael Anton September 15, 2015 at 00:26

      Thanks for linking to my reference design. I think that is a first. I linked back to your page, so that people can find a good reference on how to implement the software side of things.

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    22. Eduardo November 14, 2015 at 05:16

      Hi, quick question, by using the PWM, would that also mean that If I dont change the pwm value of the outputs the motor will stay at that angle right? Is this the way BLDC gimbals work?

      Thanks!

    23. Anatolia January 11, 2016 at 21:56

      Hi, I have a problem I can not get the minimum speed on video, I tried everything, if you can give a sketch of the video evlgenii@gmail.com

    24. Robert January 22, 2016 at 13:36

      I have the same problem with motor overheating… ,

    25. omid February 6, 2016 at 17:15

      Thank you very much

    26. ang April 19, 2016 at 12:28

      HI,

    27. ang April 19, 2016 at 12:31

      HI,

      please give schematic diagram for connection with components in arduino and BLDC and L6234 please give ,

    28. Patrick May 16, 2016 at 19:03

      I’ve tested this code with Arduino and adapted to to an STM32 and it works as expected. An issue that I’m running into though is that my motors are warming up considerably. I know that as the speed goes down, torque increases which is proportional to the current flowing through the coils but is there any way to reduce the current while still maintaining the low speeds?

      • Michael Anton May 17, 2017 at 12:07

        Yes, reduce the amplitude of the sine wave that the motors are driven with. You can do this by dividing the table values by some number.

    29. mitch September 5, 2016 at 14:42

      I would love to buy you a beer but can we see the schematic?

    30. Gustavo Murta September 15, 2016 at 15:23

      Hello BerryJam. Im doing some tests with L6234 and Arduino. First test using L6234 Linear mode with HD disk motor.
      Thanks for your tutorial.

    31. Gustavo Murta September 15, 2016 at 15:23

      Hello BerryJam. Im doing some tests with L6234 and Arduino. First test using L6234 Linear mode with HD disk motor.
      Thanks for your tutorial.
      http://labdegaragem.com/forum/topics/tutorial-motor-sem-escova-bldc-driver-l6234?commentId=6223006%3AComment%3A565317

    32. John Nikhil September 22, 2016 at 12:49

      Hello guys,
      could you help me with code.. my motors arent working.. all connection to the motor driver are connected as mentioned in the datasheet.. but i get output voltage of 0.5V from all three OUT pins of the motor driver..
      could you upload the circuit diagram?? Im not figuring whether its the problem of driver or of the code..

    33. Wayne H November 30, 2016 at 23:49

      Can you tell me the exact model of motor you are using? I’ve duplicated your design using, but I get jerky motion at slow speeds. I’m using an LD-Power Model M2208-80T Gimbal Motor (at least that’s what it seems to be, although I got it on eBay, so perhaps it’s a fake.) I’m using your exact code, but driving the motor with a SN754410NE, Dual H-Bridge. I’ve published a video that shows the jerky motion I get, here:

      https://www.youtube.com/watch?v=6KA20IaC94s

      Looking at it, you might think it was binding on something, but it’s not. The shaft is free to rotate and spins feely when unpowered. Any thoughts?

      Wayne

    34. tngotran December 9, 2016 at 09:54

      There is one note about delay() function when someone follow this thread. delay() function only receive an integer parameter. If you want delay(0.5 milisec) you should use the delayMicroseconds(500) instead.

      – one period of sin (mentioned as electrical degree as in above pics) will just

      – use ollioscopte to see the wave form of IN and OUTPUT pins. You can also compare how good is your DIY driver circuit with other. In my case, I see this link (http://manton.wikidot.com/open:bldc-motor-driver) is much better than in application note.

      – With the 360 values sine reference table, the arduino passes 60 pwm values to IN pin to make it finish 1/6 of electrical revolution. mechanical revolution is rotor spinning one circle. One mechanical revolution in this thread contains 6 electrical revolution. One electrical revolution contains 6 control step.
      In this link:
      http://elabz.com/brushless-dc-motor-with-arduino/
      electrical revolution is cycle.

      – DIY circuit has better quality than one in application note

    35. Ali January 23, 2017 at 09:51

      Hi Dears

      I’ve faced with a new nice problem in my thesis.
      please help me to solve it.

      I have a system which has two parts spinning in opposite direction relative to each other. In other words it is a

      dual spin system. Both of them has 4 canted fin that leads to rotate them about their longitudinal axis when the
      system is subjected to the wind (like wind turbine). Their spin rate is approximately high and is closed to 50 HZ.

      I want to control the position of part1 (roll angle) relative to the Earth horizon (not relative to part2).

      I decided to use a BLDC motor as an alternator in this system which its stator is fixed in part1 and its rotor is fixed in part2.

      Actually I want to do a brake by this alternator (bldc) for position control of rotor relative to the Earth horizon

      Also I can save electricity energy by this configuration as a generator.

      Question1 : Is this solution possible?

      Qestion2 : What specification shoud this bldc motor have?

      Question : Have you ever seen any application in this configuration by BLDC or electric motor?

      Thank you so much

    36. Alf March 4, 2017 at 19:44

      Hi …. great work … bought L6234 and connect to arduino mega and to ATmega644 too
      …works great but when making it more complex and adding some flashing leds to the script everything goes good until motor is off [ in program I add switch to pull LOW EN1,2,3 ] but when on, motor works nice but leds flashes in random way totally out of control .. any idea why ?

    37. Owen White March 11, 2017 at 18:37

      Greetings people.

      Be advised that there are wonderful boards out there that work really well for driving brushless motors.

      Search on: “Martinez gimbal controller driver”.

      These boards are open source and there are a number of adaptations of them, but the revolve around this circuit:
      https://github.com/owhite/brushless_gimbal_motor/blob/master/docs/BGC.pdf

      The boards are wonderfully designed, and stupidly cheap.

      I adapted the berryjam code for this board, it is here:

      https://raw.githubusercontent.com/owhite/brushless_gimbal_motor/master/simple/simple.ino

      It’s just a variant of the original code shown on this blog, with some of the pins hardcoded in. Enjoy.

    38. Doga April 21, 2017 at 10:37

      For thos who can’t make it run smoothly at low speeds, try implementing a trapezoidal waveform and a lookup table accordingly. Your motor is likely not to be a sinusoidal EMF motor but trapezoidal EMF motor. That was the case for me.

      So, take this into account.

      As for schematic. Check the application notes pdf provided in the beginning of the article. It shows all the connections you need.

    39. m4h May 6, 2017 at 19:34

      hi.how to shift phase the pwm wave?

    40. Misha October 4, 2017 at 09:30

      Hi

      Works awesome, one problem though. I want to run two motors with two chips/circuits/etc.

      This means that pins need to change. Now I have tried a good variety of pins in conjunction with changing the pin numbers in the “void setPwmFrequency(int pin)” function. But I have been unsuccessful.

      What do I need to do to change pins so that I can run several circuits/motors on the same arduino?

    41. richard September 11, 2018 at 14:18

      Hi, nice !
      I appreciate your work. I have implemented a svpwm and the motor is chopping when speed reference is very very low. From your feedback, are the speed KP KI only the way to solve the problem ?
      Best regards

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