Brushless dc motor diy.

Post here information about your own engineering projects, including but not limited to building your own car or designing a virtual car through CAD.
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coaster
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Joined: Sat Jun 30, 2012 4:10 am

Brushless dc motor diy.

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These car alternator to brushless dc conversions on the internet are very enticing, most use a 100 amp esc and a servo tester or arduino.
The ultimate would have to be the replacement of the iron rotor with an alloy billet and pressed in neodymium magnets.
Personally im about to embark on a coversion for drill press just to get a feel for this stuff.
Are there any others dabbling in this stuff?

Tommy Cookers
Tommy Cookers
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Joined: Fri Feb 17, 2012 3:55 pm

Re: Brushless dc motor diy.

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I imagine dabbling with simple conversion ICEV-to-EV at scrapyard prices (apart from a modern battery of course)

old-tech ie crude control of a wound-field motor is made viable by driving through ICEV automatic transmission ....
https://www.industrial-electronics.com/ ... _2n-s.html shows (at bottom) eventual reduction in torque at high load
torque reduction at high load/low rpm (like an ICE) is how the torque converter naturally holds the motor rpm ....
ie the motor torque is proportional to the motor-supply voltage (controlled by a pedal and by switching)
motor torque fall-off as current draw increases with load is due to increased armature flux weakening the field flux ....
this armature reaction happens with any wound field (and weakly with a permanent magnet field)
AR is unfashionable but does somewhat help motor behaviour at high load to be suitable for vehicular use

the combination of automatic transmission and electric motor behaves essentially like an automatic ICEV

selecting discrete supply voltages using switches (& part-time continuous voltage control) makes a driveable car
trains switch resistances and/or field connections in many steps (no torque converters)
but we can also switch battery voltage - and resistance losses even in eg shunt-connected wound fields are quite low

driving was always influenced by ICE/transmission characteristics .... but we only now admit this (to praise the EV)
no need to admit anything with my old-school EV around !
Last edited by Tommy Cookers on Fri Jul 01, 2022 11:47 am, edited 2 times in total.

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coaster
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Joined: Sat Jun 30, 2012 4:10 am

Re: Brushless dc motor diy.

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Ok, i get that, switching controls rpm, voltage controls torque, eliminates the need for rare earth, motors readily available.
Tell me, those big 3 phase motors are too oversized for esc's and would need a heftier vfd/vsd, can those deal with a variable input voltage?
Or you have bespoke system maybe?

Tommy Cookers
Tommy Cookers
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Joined: Fri Feb 17, 2012 3:55 pm

Re: Brushless dc motor diy.

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sorry about my lack of answers (as always)

my boss 35 years ago said he didn't want brushless
(I found better brushed machines with no rare earths but armatures wound for $5 to match our ideal voltage constant)
though he accepted in a later project my choice .... a 2 phase brushed machine
some were free outline schemes for advice on applications of development aid money ....
I once identified as the best drive a linear (power) amplifier by Seidel ? (cancelled ex-radar ? ....)
maybe 40% efficient - that's a lot of heat with eg 80 axes in a control room in a hot country
yes we also did quite a lot of proper work

(I still think that) old motors could for fun replace the ICE in an automatic car
in principle even just connecting the motor leads across the battery terminals would drive the car down the road
not so different from the first century of electric traction on rails (some still in use today)

Greg Locock
Greg Locock
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Joined: Fri Jun 29, 2012 11:48 pm

Re: Brushless dc motor diy.

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Here's one I designed earlier (well I was the mech eng, Howard did the electromagnetic design, and Vlad Dollista did the proper CAD)

https://www.researchgate.net/publicatio ... ic_vehicle

The rubbish Autocad cross section was sketched up on my computer in a Sydney bedsit on a Tuesday evening in 1996, it was my first attempt to get the packaging right, and more or less remained like that. At the time we could have had the magnets supplied and cut to shape for $500, I expect they'd be cheaper now. The wheel itself was supposed to be magnesium castings, but in practice we couldn't get them true, so went to spun steel, a much better solution.

Here's the production version, and a pretty good description (but it still has my Autocad!)

https://renew.org.au/wp-content/uploads ... _motor.pdf

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coaster
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Joined: Sat Jun 30, 2012 4:10 am

Re: Brushless dc motor diy.

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97.3% efficent could silence any critic.
Really impressive motor, nice.

Roookky
Roookky
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Joined: Sun Jul 17, 2022 4:25 pm

Re: Brushless dc motor diy.

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Thank You very much Greg for these documents.
Since I discovered the TORUS architecture in a CSIRO workpaper about AURORA, in the late 90's or early 2000 I have been searching for years.
In fact I downloaded all publicly available documents including the "4 Mofsets power control module" bluprint , but all was lost with a stollen laptop.
So, I registred on this forum today after googlizing DIY BRUSHLESS AFPM, as I have been used to do, every few months since some years.
Actually today is a lucky day for me.
Cheers
Roookky

Roookky
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Joined: Sun Jul 17, 2022 4:25 pm

Re: Brushless dc motor diy.

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I should have had that I have a png file from the start up LaunchPoint which displays the Power Density vs Shaft Speed @ 93% efficiency.

Unfortunatly I have no idea on how I could share this png.file on the forum, if anybody interested I can send it

Regards
Roookky

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hollus
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Location: Copenhagen, Denmark

Re: Brushless dc motor diy.

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I would like to see a paleontologist.

Roookky
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Re: Brushless dc motor diy.

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sORRY? i AM NOT A DIGITAL NATIVE? i DONT HAVE ANY FACEBOOK ACCOUNT OR SIMILAR? SO i CANNOT POST IT

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coaster
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Joined: Sat Jun 30, 2012 4:10 am

Re: Brushless dc motor diy.

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Google search for a " free image host ",
Sign up for an account,
Keep image file size less than half a megabyte, 400kb say.
After upload to the host copy the link as text,
Paste it into the post on this forum.
Yeah, its a royal pain, its about as good as it gets in this forum, the mods use Apple 2c and 2e it is told.

Just_a_fan
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Re: Brushless dc motor diy.

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Roookky wrote:
Sun Aug 07, 2022 9:59 am
sORRY? i AM NOT A DIGITAL NATIVE? i DONT HAVE ANY FACEBOOK ACCOUNT OR SIMILAR? SO i CANNOT POST IT
Go here: https://imgbb.com/

Click on the start uploading button, select file from your drive, upload.
Copy link given by the site, paste link in to a post on here.
Turbo says "Dumpster sounds so much more classy. It's the diamond of the cesspools." oh, and "The Dutch fans are drunk. Maybe"