Instructables

BLDC Motor Control with Arduino, salvaged HD motor, and Hall Sensors

There is a lot of interest these days among hobbyists in controlling brushless DC (BLDC) motors, which have improved performance and better energy efficiency over
traditional DC motors, but are more difficult to use. Many off-the-shelf products exist for this purpose. For example, there are lots of small BLDCs controllers for RC
airplanes that work really well.

For those wanting to delve more deeply into BLDC control there are also many different micro controllers and other electronic hardware intended for industrial users and
these usually have very good documentation. So far, I have not found any comprehensive descriptions of how to do BLDC control with an Arduino microcontroller. Also, if
you are interested in doing regenerative braking, or using a BLDC for power generation, I have not found many products that are suitable for use with small motors or
much information on how to control a 3-phase generator.

This instructable started out as a demonstration project in a class on real-time computing, and which I continued after the class ended. The idea for the project was to
demonstrate a scale model of a hybrid electric vehicle with flywheel energy storage and regenerative braking. The motors used in the project are small BLDCs
scavenged from broken computer hard drives. This instructable describes how to implement BLDC control with one of these motors, an Arduino microcontroller and Hall-
Effect position sensors, in both motoring and regenerative braking modes. Note that having access to an oscilliscope is extremely helpful, if not essential, to doing this
project. If you don't have access to a scope, I have added some suggestions for how it might be done without one (step 5).

One thing that this project doesn't have that should be included in any practical motor controller is any safety features, such as overcurrent protection. As it is, the worst
thing that can happen is that you burn out the HD motor. However, it would not be too difficult to implement overcurrent protection with the current hardware, and perhaps
I will do it at some point. If you try controlling a larger motor, please do add overcurrent protection, to protect your motor, and for your own safety.

I would like to try using this controller with a larger motor that can do some "real" work, but I don't have a suitable motor yet. I noticed an 86W motor for sale on eBay for
around $40.00 that seems like a good candidate. There's also an RC website called "GoBrushless" that sells kits for putting together your own BLDC. These are not too
expensive and building one is a worthwhile experience. Note that the motors from this web site do not have Hall sensors.

Whew! It was a lot of work to write up this instructable. I hope you find it useful and please post your comments and suggestions.
 
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edwinjohn8 months ago
Hi.
I am doing a project based on the speed control of a bldc motor by pulse width modulation using an Arduino board. However, my motor does not have a hall sensor to provide the feedback on speed to the arduino. My set up involves using an esc (electronic speed controller) to link the bldc with the arduino. Can you suggest some method to achieve the required results with my components.
Great page by the way. Cheers!
dlginstructables (author)  edwinjohn6 months ago

Hi, I thought I had replied to you already. Anyway, The ESC is controlled by using PWM at a certain frequency (I forgot the value, but you can look it up). You will need some method of measuring the rotational speed of the motor, to give your control system feedback. I tried measuring the back EMF period from a motor with an ESC, but the act of measuring it interfered with the ESC (which uses sensorless control). So, you either need an encoder on your motor, or a hall sensor. Both of these are fairly straight forward to implement, if your motor geometry permits either or both.

daleshco6 months ago
Awesome project!
dlginstructables (author)  daleshco6 months ago
Thank you!
mfranco107 months ago
Hello,

Im using a 24V 200w BLDC motor,
what components here do I need to adjust?
hi! thanks yor this instructable! it is amazing!...
I am working in a proyect, and I wonder if you could help me to figure out how to do one thing...
I want to be able to set the speed of a BLDC motor, mecanicaly, I mean imagine that you manually give speed to the motor and then it keeps the speed for it self untill you stop it, actually I would like to use regenerative breaking to stop it...
(I am talking about a 14.8V / 800W / 50A brushless motor)
I was thinking about hall sensors for determinate at what speed is the motor mecanicaly rotating, and then use an arduino to set that speed as the constant speed for motor. So the only inputs for this sistem should be the hall sensors (no other input to set the speed of the motor) and the break.
Do you think this is posible?
I only need one direction in the motor, so could I use a standard ESC to control the motor speed? or you think that is better to make my own ESC like you did?
tell me what you think!
thanks!
dlginstructables (author)  lucianorueda1 year ago
Hi, can you answer these two questions?
1. What tolerance do you want for constant speed? For example 500 ±25 RPM
2. How much will the load on your motor vary?

If you use just an ESC, controlling it is like the gas pedal on a car. You can hold the pedal in the same place and go a constant speed, but if you go up or down a hill, then you will have to change the pedal position to keep your speed constant. So, you will need a feedback loop. If you make the Arduino control the motor commutation, like my instructable, that keeps the Arduino very busy, and it may not be able to handle speed control at the same time.

A good way to go would be to use an ESC and then use the Arduino, with hall sensor feedback and a PID controller, to control the speed. I think that most (all?) ESCs for RC airplanes use sensorless control. Does your motor already have hall sensors?
elabz1 year ago
I love to spin these up to 10,000 RPM + myself but just a bit of a warning is in order here I think. Just yesterday I've opened a 2.5" (laptop) HDD in which the platter has shattered to thousand very dangerous looking glass shards. I assume not all HDDs have ceramic platters, especially not very old ones, but if they do, you spin it up high and it breaks from vibration or you've overtightened the bolt(s) or something like this, the result would be very much like an explosion of a grenade and someone will end up in a hospital or dead. For any serious RPMs you need to have some sort of a cover - the HDDs own body is nice or perhaps a cover from a 100-CD blanks box or some such.

Other than that, happy spinning!
dlginstructables (author)  elabz1 year ago
Thanks for the comment. I thought that the hd platters were made of metal, but I looked it up and some of them are in fact glass/ceramic. In my project, I had several of them glued together and they were never screwed down tightly, but, when I get a chance, I will add a suggestion that a clear cover be put over the platters.
CraigHyatt1 year ago
This is one of the best instructables I've seen. I like that you broke down how the Hall sensors and bridge operate in such a detailed day. Bonus that you included regenerative braking. I've read a ton of documents on this topic, and this is the first time I have actually understood what is going on. Thanks!
dlginstructables (author)  CraigHyatt1 year ago
Thank you very much for the compliment! I put a lot of work into describing everything and I like to know that people are benefiting from it. Yeah, regen braking is hard to grasp, and I by no means have it down. I don't know why there isn't more info out there about it. By the way, I recently drove a Nissan Leaf, and when it does regenerative braking it sounds pretty much the same as my little disk drive motors do!
elabz1 year ago
Not sure what you mean by "running the motor as a stepper motor, not as a BLDC" - 9 cog 12 pole BLDC motor is very much like a 36 SPR stepper. Did you mean that his commutation sequence did not include a high-Z state for one of the windings in each step?
E_motor1 year ago
awesome guide this! Just fyi, step 5's first picture tag shows 15 degrees, so does the second last line on that page, and the second line in step 7 also says 15, where they should be 30 degrees apart. Was a bit lost until I saw your exchange with Carl.
guillempq1 year ago
Is it better control 4 brushless motors through receiver or this special chip?
guillempq1 year ago
Can you write an example about the Arduino working with a commercial Brushless Motor, please?

int motor = 0;
void setup() {
pinMode(motor, OUTPUT); //analog Pin
}
void loop() {
analogWrite(motor, 255);
delay(1000);
analogWrite(motor, 40);
delay(500);
}
But it doesn't work?
Regards and thanks
dlginstructables (author)  guillempq1 year ago
The arduino digital pins can only output a very small amount of current, so if you have your motor directly connected to the Arduino, I wouldn't expect it to work. What you need to do is use the analogWrite output to control a separate power source.

Here is one instruct able that uses a special chip for controlling motors that will allow you to operate the motor in both directions: http://www.instructables.com/id/Control-your-motors-with-L293D-and-Arduino/?ALLSTEPS

If you only need to run the motor in one direction, then you can use a MOSFETtransistor like this one, which has a link to an arduino tutorial:
https://www.sparkfun.com/products/10213

Good Luck!
mhyanni1 year ago
Man,You're Great !!
I'm gonna start on the Project thanks for your help my friend !
dlginstructables (author)  mhyanni1 year ago
Thank you. I put a lot of work into this instructable, and I hope it helps you do the project successfully.
tomshirvo1 year ago
Hi,

Yes they all support 2A but after some troubleshooting I found that the motor only draws .05A from a working 3 phase controller I have. I did find that one of the hall sensors is not working correctly.

I have tested everything;
I tested that the out puts work High, Low and NC they are fine. I am using 24V and not 12V like you did, does that mean that I should have made some changes with resistors. The one thing I did do was connect both the Sense one and two together and then connected the resistor to GND.

The motor just doesn't seem to spin at all.


dlginstructables (author)  tomshirvo1 year ago
There are three Hall Sensors and each one must have its own resistor and its own input to the Arduino.

Have you tried getting the motor to turn by manually powering the phases (see step 4)

Step 1 2 3 4 5 6
Clockwise: CB, AB, AC, BC, BA, CA
Counter Clockwise: BC, BA, CA, CB, AB, AC]

have you tested the Hall sensors? You should be able to make them go high by putting a magnet near them.

Do you have an oscilloscope? It helps to have that to see if the hall sensors are in synch with the motor (you can spin the motor by hand and watch the sensor output
Ok really strand thing, even though my multimeter give me a reading of 24v out of the outputs 1,2,3 when I make output 1 positive and output 2 negative I get a reading out on the multimeter 24v. BUT this is a big but, when I connect just a plane old dc motor to it nothing happens. If I put the motor on the 24v directly it works fine.

I keep thinking that it has something to do with the sense 1 and 2. you did say that you needed a 400ohm from sense to GND but mine is 470ohm.

dlginstructables (author)  tomshirvo1 year ago
Try measuring the voltage of the output while the DC motor is connected. If the voltage goes way down, then maybe not enough current is being supplied.

I don't know if it makes a difference to have 470 or 400 ohms on the sense pins.

I need to go back and read the instructable because I have forgotten so much. I will do that when I have time.

I have done the same and I don't know where I got the 400ohm resister from. I took that out of the system and it WORKS, sort of. It seems to spin some of the time. Some times it will spin for a while and then start to slow down and stop. Some times it will turn once and stop. and so on.

Thanks for your help so far i'm very grateful, but if you have any ideas with the new problem I'm happy to hear it.

Thanks again
dlginstructables (author)  tomshirvo1 year ago
Also, take a look at the Hall sensor calibration, to make sure that it matches the back EMF
dlginstructables (author)  tomshirvo1 year ago
Sorry I haven't replied in a long time. Have you had any progress? Based on your last message, I would take a look at the sequence of the motor's back EMF and make sure that your software is firing the digital outputs in the correct order. Do you have an oscilloscope to look at this?
One hall sensor is dead I'm not sure why but the others all work and my circuit works for that.

If you put the motor on a motor controller I have it works fine.
If you just take two of the phases and put them across the positive and negative terminals the motor moves a fraction.

I have a multimeter and when I put it on the terminals I can get a positive and negative and NC reading from each of the 3 phases of the out pins.

I have gotten this motor to turn just using relays it was slow and very noisy but it worked my point is the motor works.

I will list a few of the voltages coming off the L6234 below;
Vs: 24v
VBOOT: 31.7v
VCP: 4.61v
VREF: 9.24v
Sense 1 & 2: 0

I hope this helps. I'm so stuck right now. I don't understand how I can get voltage out of each output but nothing works



tomshirvo1 year ago
Hi,

I have been trying to follow this instructable and I just cant get it to work.
I have built the electronics but the nothing works. the only difference is that I am using a 24v 2A BLDC and a Arduino UNO R3

Do you know if the code doesn't work with the UNO R3
dlginstructables (author)  tomshirvo1 year ago
Hi, you are the first person to write that you are trying to do this project :)

I wrote the code for a Duemilanove, but I think it should work fine with an UNO. I did this project three years ago, but I can try and help you troubleshoot.

My first question is: Do all of your electronic components support 2A?

Second, you say that nothing works. Why don't you start with an individual step iin the instructable and describe what is happening.
chuvso2 years ago
How can I check operation of Hall sensor?
Can I check it by Sanwa Analog Multitester ?
dlginstructables (author)  chuvso2 years ago
The best way to test the Hall sensor is with an oscilloscope, but you can use a multitester (we call it a multimeter in the U.S.).

First, connect the sensor as shown in my instructions, and then move a magnet slowly across the sensor. When the sensor works, you will see the voltage go high when it senses the magnetic field. A refrigerator magnet is useful for this, because it has stripes of magnets and as you move it across the sensor, the voltage will go high-low-high-low...
Pash19872 years ago
I'm relatively new to Arduino and am currently still finding my feet on it.

I am designing a parking sensor and need to use the analogWrite() function to control my sensor as the tone() function is tied up somewhere else.

I was wondering if you could run me through how you altered the frequency of the analogWrite() PWM.

Any help would be greatly appreciated.
BradyZ Pash19872 years ago
You modify the TCCRnB ('n' is the number of the timer) register for one of the TIMER's. The ATmega328P has 3 timers (TIMER0, TIMER1, and TIMER2). If you want to change the PWM frequency, you just modify the prescaler value for whatever timer you want to change. TIMER0 is used for delay() and millis(), so it's better to use any timer other than TIMER0; but usually nothing bad happens if you modify TIMER0. Your program just wont have/use the correct values in delay() and millis(). To change the PWM frequency on pins 3 and 11 (they use TIMER2) to be ~4kHz (3906.25) you simply place the following line of code in your "void setup()" space:

TCCR2B = TCCR2B & 0b11111000 | 0x02;

- The default for TIMER2 is "0x04"
- If the code is confusing, check out these links for some help:  
      -http://arduino.cc/en/Reference/Boolean  
      -http://arduino.cc/en/Reference/BitwiseAnd  
      -http://arduino.cc/en/Reference/BitwiseXorNot
      -http://arduino.cc/en/Reference/Bitshift

This will work on any 'ATmega' or 'ATtiny' that is supported by Arduino (install ATtiny 'cores' to program them with Arduino 0022 or Arduino 1.0)


I did not figure this stuff out myself. I'm just passing the information onward. Check out this page in the Arduino Playground. It's extremely helpful!
      -http://arduino.cc/playground/Main/TimerPWMCheatsheet
Nakiros2 years ago
For higher power you should better turn to mosfet bridges(like the irf3704s-77A@10V) and gate drivers (ir2101 or ir2110). Just google 'Open BLDC' and you will find more info.
Spydamonky4 years ago
 so is the speed of the motor variable? cause im making a autonomus hexacopter and need a speed controller based on a arduino. also dus it use the hall effect sersors for the speed control or only for braking. is there any feedback about the rmp?? ie can you read off the current rpm of the motor any time ??
the speed of the BLDC motor is determined by the frequency of the pulses of voltage sent to the stator windings. So what you need to do to increase the speed is to reduce the period of the signal and vice versa.
dlginstructables (author)  Spydamonky4 years ago
I'm also interested in building a quadracopter, but I wouldn't recommend this for your project. Yes, the Hall sensors can be used to vary the speed, but it pretty much takes all of the arduino's capacity to do the motor commutation. There wouldn't be much computing power left for other functions, and you would need one arduino for each of the 6 motors, plus another to do the control. I know that commercial electronic speed controllers are not cheap. There is one, the Markus 10 that only runs about $25. It's very small but powerful enough for your needs.

Thanks for your interest.
lampuiho2 years ago
Are you controlling the field current directly? If not, that's probably the reason why it didn't work well.
Gnutella2 years ago
My HD motor has 4 contacts . can you please explain how i could make them turn clockwise and counter clockwise? explain it to me like youre explaining it to a Four year Old.
dlginstructables (author)  Gnutella2 years ago
Three of the contacts are the three phases and the fourth one is the center tap, where all the phases meet (search on the Internet for "BLDC Wye Configuration") This contact can be used as a sort of reference "ground" voltage, but you don't need to use it for the control scheme described in this instructable.

Use an ohmeter to figure out which are the three phases and which is the center tap. The resistance between any two phases should be double the resistance between a phase and the center tap.

As far as getting your motor to spin CW or CCW, please read the instructable carefully, as I believe I put detailed instructions on how to do that. If you still have problems, send another comment.
rany2 years ago
Thanks a lot for the the nice upload ... superr..
carl3 years ago
It looks to me like the hall sensors need to be 30 mechanical degrees apart, which I think would be 120 electrical degrees. Am I making a conceptual error? My motor has 12 slots and 8 poles, which appears to me to be similar to your motor.
dlginstructables (author)  carl3 years ago
It's been a long time since I designed the system, so I'd have to go back and confirm why I chose 15 degrees, but I know that it works this way. I believe there are often multiple ways to configure hall sensors on a motor, so 30 degrees may work as well.
Thanks for the reply. I too am trying to learn about bldc motor control by starting small. I wouldn't have questioned the 15 degree spacing except that I couldn't fit my hall sensors 15 degrees apart without overlap on a sketch of the rotor diameter. From your photos it looked to me like your hall sensor holder was built at 30 degree spacing (it looks like an equilateral triangle will fit between the center and the outer two Hall sensors). I thought I'd ask before I started hacking into my holder material. I guess this is the opportunity for learning that I was looking for!
dlginstructables (author)  carl3 years ago
I'm happy that someone is actually using this Instructable! I wrote 15 degrees in my text, but I'll try and take a look at it this weekend. Do you know how to actually figure out hall sensor spacing on a motor?

I'm curious, do you have access to an oscilloscope?
I drew a sketch of the poles and sensors, then rotated the poles to try to understand how the signals change during rotation. A 30 degree spacing works. A 15 degree spacing does not work (a 111 and 000 shows up at that spacing since the sensors span 30 degrees and a pole spans almost 45 degrees). It looks like the image in step three shows sensor B output inverted, making it look like the sensors should be spaced 60 electrical degrees apart when they should be 120 electrical degrees apart. That's my story at the moment. I will need to throw something together and put it on the oscilloscope and see what happens.
dlginstructables (author)  carl3 years ago
You are right! My sensors are placed 30 degrees apart, which is 120 electrical degrees. I corrected the text. Thanks for catching that!
carmatic3 years ago
This looks like 'dynamic' braking rather than 'regenrative' braking, as in the motor is basically shorted out, and the energy would be dissipated as heat in the wires... I do not see how the energy is stored from braking?
dlginstructables (author)  carmatic3 years ago
Please read Step 9 for a detailed description of why this is regenerative braking. In my video, I should have shown a DMM measuring the current between the battery and the motor controller. In fact, during the regenerative braking, it can be seen that the current does flow into the battery, albeit for just a couple of seconds at the peak of the braking.
okay yeah, i see the third picture now... for some reason the last time i viewed this, the picture showing current flowing into the battery didnt show up

i think that it is better if there were 2 indepenent circuits between the bridge and the battery, one for driving the motor with the pwm control and back emf sensing as well as controlling the transistors in the bridge, and the other for charging the battery with some form of voltage regulation and maybe some charging circuitry designed for the type of battery being used... and using solid state relays to switch between them when the brake is pressed
dlginstructables (author)  carmatic3 years ago
As I say in the instructable, I found very few references on how to implement regenerative braking and I used the best one that I had at the time. Do you have a circuit diagram that shows your idea, or could you draw one up?
jaillela3 years ago
Thank you very much for sharing this project.

I´ve got a question. When using regenerative breaking, you are not drawing any current back to the battery, right? and also, for regenerative breaking, are the hall effect sensor necessary?

I am asking you this questions, because I would like to use the energy from the breaking to control the breaking torque and by the way recharge a battery.

Best Regards and thanks again for your work.
dlginstructables (author)  jaillela3 years ago
The regenerative braking does send current back into the battery. In my small system, I think the efficiency was very low, but I did not measure it. The hall effect sensors are necessary for regenerative braking and also for regular motoring. There is a way to do this without them that is called "sensorless bldc motor control". I have also done some work on this, but have not been completely successful.
evaleto3 years ago
Thank you so much for your work!
I read all paper you gave for understand how BLDC work. Unfortunately, I don't know how to find a driver (like L6234) but for motor with higher power 37V/10A.

regards,
oe
chaitanyab4 years ago
This is really nice info with great illustration,thanks.
AKA the A4 years ago
http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=9821 It's a motor suited for 1:10 RC cars, has sensors built in and (get this) costs $16!!! Quite a nice (and cheap) way to scale up this project...
dlginstructables (author)  AKA the A4 years ago
Thanks for the tip! Definitely looks worthwhile at that price.