Partly OFFTOPIC - ESC controller and motor construction

Hi to all !
Am planning to make one BL high speed motor based on this design.

Construction will be a bit different and stronger then the one in video.
I dont know power output of the motor in video but my goal is to create one 200W DC motor with 5000 - 6000 RPM. Main thing is that i need to try to have constant power output at speeds up to 4000 RPM. After that
performance can drop. I understand that this is not easy to design so any help is more then welcome.

Questions.
1.) How many turns and witch wire gouge would be needed to accomplice this performance and how many pole magnets should I use. ?

2.) Based on this setup i would like to build controller for this motor with some LCD output and maybe future remotely speed control. Real question is, would it be better to use some ready made solution for controller or to DIY ?

OK, any idea and comment is welcome !
Arnix.

IF you want to CONTROL the power output, you have to measure it to detect variations. I don't know how you will do that.
Paul

  1. You want the most turns with the thinnest wire and as many poles as possible. When trying to achieve higher RPM both Balance and the friction of the bearings become the primary limiting factors.

  2. Definitely go for ready made.

You would get more (and better) answers if you had posted this in the General Electronics section of the forum.
You can click "report to moderator" in your post and ask a moderator to move it there for you.

Hutkikz:

  1. You want the most turns with the thinnest wire and as many poles as possible.

Isn’t it a little more complicated?

The force depends on the current x number-of-turns so 2 amps in 10 turns would be the same as 1 amp in 20 turns - but you need a higher voltage to get the 1 amp through the 20 turns.

In my (limited) experience with brushed DC motors the fast motors have had fewer turns of heavier wire.

…R

Hi guys !

I would agree that it's not that simple to create such motor specially because i want to have constant power and speed. If i define 10 poles and 14 slots I think i would need at least 80 winding with 1.00mm wire.
My problem is that i can not define, how much would be the correct value. Beside, i would use iron core instead ALU. I guess that such motor should have 0.6 or so Nm torque but then how to keep this torque at higher speeds.
It's easy to test some motor without load :-). I dont know, but i dont think i can pull this with 200W or with such
winding scenario..

2.) Can you share some link for ready made esc controller but for 300- 400w motors ?

A.

Where do the 80 windings come from? I fear that you did not yet understand the number of and relationship between all involved parameters. Keeping so much information secret will defeat any assistance :frowning:

arnix:
2.) Can you share some link for ready made esc controller but for 300- 400w motors ?

Hobby King sell a wide range of ESCs

The shape of the windings also matters - longer wires in the magnetic field are better. IIRC the formula for the force on a wire is B.I.L where B is the magnetic-something-or-other, I is the current in amps and L is the length in metres.

...R

From magnet coil layout I remember current*windings, independent from wire length.

If you want constant power of 200W, at 1000 RPM, torque would be 1.91 Nm, at 4000 RPM, 0.4475 Nm. As speed increases, torque will have to decrease in proportion. Not so easy. :confused:

If you want constant power of 200W, at 1000 RPM, torque would be 1.91 Nm, at 4000 RPM, 0.4475 Nm. As speed increases, torque will have to decrease in proportion. Not so easy. **** Yes, you are correct about that its not easy as it seams..How did you get 1.91Nm at 1000 RPM ?

IIRC the formula for the force on a wire is B.I.L ****
am trying to calculate needed wiring based on this How to Calculate Toroidal Transformers | Sciencing, but as Diettrich pointed out my lack of knowledge in this part prevents me to solve this problem.
200W is not fixed value so we can increase this to 400W, but it would be interesting to pull this speed and keep the torque and power at 200W range.

arnix:

IIRC the formula for the force on a wire is B.I.L ****

am trying to calculate needed wiring based on this How to Calculate Toroidal Transformers | Sciencing, but as Diettrich pointed out my lack of knowledge in this part prevents me to solve this problem

I'm not qualified to calculate the design of an electric motor - I would not even try to do it for myself. But it seems to me a transformer is a very different thing as it has no moving parts.

If you want to design an electric motor find a website that describes how to design an electric motor.

...R
PS ... I have checked with my physics text book and B.I.L is correct. B is the magnetic field.

@Robin
*of course, i agree with you but that was the closes that i found…
After some more research i found this: https://motoranalysis.com/ and i will download it.
Maybe this can help somehow…

Btw.
hobby king → wow :-).

It is hard to tell how many turns you need to get to a specific motor speed per volt (RPM/V or KV).
The 42mm diameter brushless outrunner I have been rewinding with thicker 0.8mm copper wire has 12 stators and 14 magnets. I used 9 turns.
It gives 520 revolutions per minute per volt. So at 12 volt without a load it runs max 6240 rpm.
I use it at 24 volt with a load of approx 1.000 Watts (model airplane)

If you need constant power, which I perceive different from constant speed, then you could add a current sensor (assuming stable power supply voltage) like the Allegro ACS758 and manage the throttle based on the sampled current.

If it is just for fun, making your own BLDC motor go for it. If it is for real use, I would never make it myself but buy a cheap 35mm diameter outrunner engine

HI !
Yep, you can call it fun but if it will work then i would like to make few more.
Can you suggest motor that would fit my needs ?
Shortly:

  • constant power of up to 300W
  • load weight --> 600 grams
  • speed min 3000, max 6000

Allegro --> nice :slight_smile: Very useful !
So, how did you calculate those 9 turns ?

I downloaded MotorXP design studio and i must say that this is one heck of software. I didnt test it yet but according to options, it's amazing. Basically you can construct your own motor from scratch, run winding and geometry editor etc..

i did not calculate. It was a 9 turn motor with damaged windings and I did not want to change the RPM/V

Given your specs 3-6K rpm and 300W I would look at something like this

at 12V and 25 Ampere, that should give you 300W
I would not go for a power supply of less than 40A

A forum for the hobby use of microprocessors is not the place to learn how to design motors. That’s not to say there are not people here that know motor design but you will get some very wrong ideas and bad advise, it’s the Internet, the place where everyone knows something and the Dunning-Kruger effect is full display everyday.

Stick to buying your motors. In the end, you’ll spend less money and have something that will actually work. If you did want to design a motor, you never start with the final item you want to produce. You start with the basics, learn how they work by building different designs, pole counts and speed ranges. Then you actual try to build something that will be useful for your application.

It’s a lot like brain surgery. You don’t become a surgeon by starting with a live patient, popping the top off their skull and poking around for on the job learning.

WattsThat:
You don’t become a surgeon by starting with a live patient, popping the top off their skull and poking around for on the job learning.

Spoilsport. :slight_smile:

...R

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