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

Picture of 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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chuvso3 years ago
How can I check operation of Hall sensor?
Can I check it by Sanwa Analog Multitester ?
dlginstructables (author)  chuvso16 days ago

You can check it with a DMM or a scope. Put any magnet near it and it should change the output from 0V to your source voltage. The best way is to put the magnet ring that will be used next to the senor and rotate it. You should see a square wave.

dlginstructables (author)  chuvso3 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...
ignasg1 month ago

Thanks a lot. Using Your information, I made mine adaptation for driving BLDC at very slow speed:

http://www.berryjam.eu/2015/04/driving-bldc-gimbals-at-super-slow-speeds-with-arduino/

dlginstructables (author)  ignasg28 days ago

Awesome! Glad my project was helpful to you.

DerickK1 month ago

why are we using hall sensors ..i"ve seen some running them using arduino without the hall sensors ...what is the advantage

dlginstructables (author)  DerickK1 month ago

As I explain in the Instructable, the two most common ways to control a BLDC are with hall sensors, and "sensorless", which uses the back EMF waveform for feedback on the motor's position. The easiest approach, and what I suspect you are referring to, is to buy a sensorless motor controller that is made for RC airplane motors, which can easily be controlled by an Arduino. The use of hall sensors in this project was the easiest way for me to do it from scratch. I did also spend a lot of time trying to develop a sensorless controller. I got close, but I wasn't able to make it work well enough.

Zephyr932 months ago

Would it be possible to use a BLDC motor almost like a stepper? That it, to accelerate carefully,run for a counted number of cycles, deccelearate, and stop at a specified location (ie: move exactly some number of cycles, or partial cycles).

dlginstructables (author)  Zephyr931 month ago

In principle, the answer is "yes". I have run one of these motors very slowly, so I could see each individual step. However, at faster speeds, I would think that inertia would cause the motor to overshoot the exact angular location that you wanted. I think it's worth experimenting with.

rezaalfath1 month ago

Nice Tutorial!

But, why you use PWM for Enable pin in L6234 IC? not for Input pin?

Thanks!

And then, can i use the PWM for Input pin and give the Enable pin HIGH state (in this case, i just give 5volt to Enable pin, just for enabling)? can i use the same code as you use (pin declaration change too)?

snoop9113 months ago

Do I understand correctly that a BLDC/PMSM motor differs from an AC induction motor, in that you vary the current going to the BLDC's stator, which causes the magnetic field to move the dc permanent magnet on the rotor?

For trepezoidal commutation, the current is driven in only 2 of the 3 stators at a time.. and sinousoidal commutation drives current on all 3 windings. The former is good for high speed while the latter for low speed.

If so, how does field oriented control work and can it be used on a BLDC/PMSM? Also how are these system generally closed - using ((fuzzy) pid ? state space lq?

Is there any kit recommendations? I'd love to play with simulink or octave and see how this all works!

M.SUFIANI3 months ago

Hi peeps,I m about to build this circuit but I have doubt bout drain sign(arrow) at SENSE2 output.What is is actually?where should I connect to it? Thanks

dlginstructables (author)  M.SUFIANI3 months ago
Hi, it's been a long time since I built this, so I may not remember correctly, but I think that I didn't use the current sensing capability in my circuit. If you are going to use it, then I think the arrow would go to an A/D converter, to measure the voltage across the resistor. Then you would use ohm's law to calculate the current and, if it goes above your cutoff value, your software would shut down the motor. If you are going to be using a larger motor with a real load on it, then I would recommend using this feature.

Thanks Sir for your answer..One more thing,if want to make it sesorless,what your I do?just ignore all the sense pin at L6234?

ldee2473 months ago

Hi,I'm doing a project on BLDC motor controller using a 24v RS 5366024 brushless motor http://uk.rs-online.com/web/p/dc-motors/5366024/ and Arduino uno. Can anyone help with a circuit diagram and schematic on how best I can build up the circuit. I've tried looking through this project but seem to have a diagram with reference to this. http://prntscr.com/5zdjax ,thank you.

awpe005 months ago

Thank you for idea with scope, have read some forums but never seen someone using scope to align hall-sensors.

cheech_jc5 months ago

I don´t understand why you used pins 1,2,3 of Arduino, and the in the program you write "pinMode(4,INPUT)" //hall3......is it wrong?

thanks

dlginstructables (author)  cheech_jc5 months ago

Yes, I believe that my diagram is mistaken and it should show connections to pins 2,3,4. Pins 0 and 1 on the arduino are needed for serial communications, and I think I did use serial commands for troubleshooting. You're the first person to ask a question about the software! Good luck!

Hello! that was a great instructable guide! Thanks

I'd like to control 3x L6234 IC's (3x BLDC motors) with the cheapest microcontroller/board/lauchpad but i'm a bit confused about the requirements needed for the microcontroller. As i understood each motor needs 3 PWM control signals so i'd need 9 PWM's, but i'd also need 9 timers in the microcontroller right? Or can i use just 3 combined with prescalers?

I was thinking about using Arduino boards but they are still more expensive than texas launchkits (MSP430 launchpad and stellaris could do the work?).

You don't need any timers, just the 3 pwms per motor. The prescalers are used to set the pwm frequency of the ATMEL microcontroller. I don't know how cheap the TI kits are, but there are Arduino clones that are pretty inexpensive and also online instructions for using the ATMEL microcontrollers by themselves. You might also investigate the use of a programmable logic controller, which I mention in the last step of this instructable.

Ah ok thanks!

I also understood you used the INs and ENABLE pins to control the 6 sequence steps (to specify which phase was or was not being used):

Step 1 2 3 4 5 6

Clockwise: CB, AB, AC, BC, BA, CA

Counter Clockwise: BC, BA, CA, CB, AB, AC

but on the boards i have the ENABLE pin is only one (the 3 ENABLEs are shortcircuit to each other =/. I can control the PIN but on the 3 pins in separate. Is there a way to rotate the motor with the board like this?

sprocketeer7 months ago

Hi, is there any chance of a schematic of the power circuitry you used? I'm demoing this to some of my students and it would be much easier than ficuring it out from the photos. Thanks for such a good instructable by the way, really useful.

pablocv8 months ago

Hello, great proyect! do you know the range of RPM you can achieve with the L6234 and the HDD brushless (sensorless) motor?

Thanks a lot!

dlginstructables (author)  pablocv7 months ago
If I remember correctly, I got up to around 10,000 RPM with my set up. I don't remember the lower limit.
enxp9 months ago

Hello.

Is it possible to use this setup for controlling bigger motors, like 1KW.?

I
have made few dc controllers and i was planning to make one blcd
controller but this setup would be much easier . My motor is for e bike and i was planning on using 48V or 72V input (
crystalyte 1,5KW ).

Thank you for your reply.

dlginstructables (author)  enxp7 months ago
The L6234 can handle up to 52V and 5A, so you would need to find a three phase motor driver that can handle 1.5 kW, and also a set of transistors that can handle high voltage and current. Chances are that this driver will not use the same logic control as the L6234, so you would have to adapt your microcontroller program accordingly. If you are going to work with that much power, please make sure you are familiar with proper safety precautions.
edwinjohn1 year 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)  edwinjohn1 year 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.

daleshco1 year ago
Awesome project!
dlginstructables (author)  daleshco1 year ago
Thank you!
mfranco101 year 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?
elabz2 years 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)  elabz2 years 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.
CraigHyatt2 years 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)  CraigHyatt2 years 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!
elabz2 years 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_motor2 years 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.
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