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*analog* brushless DC motor control?

Started by Unknown March 5, 2013
My son and I took apart a dead hard drive, and salvaged the motor.  Apparently it's a brushless DC motor that needs a dedicated controller.

Any way it can be powered by analog, discrete circuitry?

If I understand it correctly, each of the three power wires needs to be energized while the other two wires are held at ground, and the three wires take turns being powered by, what, +5V, right?

Thanks,

Michael
On Tue, 5 Mar 2013 09:24:48 -0800 (PST), mrdarrett@gmail.com wrote:

>My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. > >Any way it can be powered by analog, discrete circuitry? > >If I understand it correctly, each of the three power wires needs to be energized while the other two wires are held at ground, and the three wires take turns being powered by, what, +5V, right? > >Thanks, > >Michael
Are there only three leads total, or is there a fourth, or a path to case? Or maybe it's two-phase instead of three? Or it could be self-commutated, with the third lead as a speed sensing output. Hard to say. Can you trace back thru the board it was on? Here's my big mama... http://www.analog-innovations.com/SED/BoschMotor1.jpg http://www.analog-innovations.com/SED/BoschMotor2.jpg http://www.analog-innovations.com/SED/BoschMotor3.jpg Three phase blower motor for Mercedes A/C system. All on one chip except for the three big HexFET's. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Tuesday, March 5, 2013 10:01:44 AM UTC-8, Jim Thompson wrote:
> On Tue, 5 Mar 2013 09:24:48 -0800 (PST), mrdarrett@gmail.com wrote: > > > > >My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. > > > > > >Any way it can be powered by analog, discrete circuitry? > > > > > >If I understand it correctly, each of the three power wires needs to be energized while the other two wires are held at ground, and the three wires take turns being powered by, what, +5V, right? > > > > > >Thanks, > > > > > >Michael > > > > Are there only three leads total, or is there a fourth, or a path to > > case? Or maybe it's two-phase instead of three? > > > > Or it could be self-commutated, with the third lead as a speed sensing > > output. > > > > Hard to say. Can you trace back thru the board it was on? > > > > Here's my big mama... > > > > http://www.analog-innovations.com/SED/BoschMotor1.jpg > > > > http://www.analog-innovations.com/SED/BoschMotor2.jpg > > > > http://www.analog-innovations.com/SED/BoschMotor3.jpg > > > > Three phase blower motor for Mercedes A/C system. All on one chip > > except for the three big HexFET's. > > > > ...Jim Thompson > > -- > > | James E.Thompson | mens | > > | Analog Innovations | et | > > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > > | Phoenix, Arizona 85048 Skype: Contacts Only | | > > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > > | E-mail Icon at http://www.analog-innovations.com | 1962 | > > > > I love to cook with wine. Sometimes I even put it in the food.
Oh, nice! Still have a controller chip in there though, huh. Wiring... I'm not sure; I'll have to check it more thoroughly when I get home. There were three very obvious wires, but from some YouTube vids I saw there is sometimes a fourth wire... I did see a very clever way to turn the hard disk platter itself into a commutator, using electrical tape, and turn the whole motor into a brushed DC motor, but that kind of defeats the purpose of a brushless DC motor. http://www.youtube.com/watch?v=CWx5ji_sFUw
On 3/5/2013 12:24 PM, mrdarrett@gmail.com wrote:
> My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. > > Any way it can be powered by analog, discrete circuitry?
Yes, but it's not worth the effort, unless the goal is the experimentation. There's a relatively cheap (< $20) controller available on Ebay that will work well to control the motor. I'd post the details if I could remember, but ... Grumble. Ed
> > If I understand it correctly, each of the three power wires needs to be energized while the other two wires are held at ground, and the three wires take turns being powered by, what, +5V, right? > > Thanks, > > Michael >
On Tue, 5 Mar 2013 10:21:14 -0800 (PST), mrdarrett@gmail.com wrote:

>On Tuesday, March 5, 2013 10:01:44 AM UTC-8, Jim Thompson wrote: >> On Tue, 5 Mar 2013 09:24:48 -0800 (PST), mrdarrett@gmail.com wrote: >> >> >> >> >My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. >> >> > >> >> >Any way it can be powered by analog, discrete circuitry? >> >> > >> >> >If I understand it correctly, each of the three power wires needs to be energized while the other two wires are held at ground, and the three wires take turns being powered by, what, +5V, right? >> >> > >> >> >Thanks, >> >> > >> >> >Michael >> >> >> >> Are there only three leads total, or is there a fourth, or a path to >> >> case? Or maybe it's two-phase instead of three? >> >> >> >> Or it could be self-commutated, with the third lead as a speed sensing >> >> output. >> >> >> >> Hard to say. Can you trace back thru the board it was on? >> >> >> >> Here's my big mama... >> >> >> >> http://www.analog-innovations.com/SED/BoschMotor1.jpg >> >> >> >> http://www.analog-innovations.com/SED/BoschMotor2.jpg >> >> >> >> http://www.analog-innovations.com/SED/BoschMotor3.jpg >> >> >> >> Three phase blower motor for Mercedes A/C system. All on one chip >> >> except for the three big HexFET's. >> >> >> >> ...Jim Thompson >>
[snip]
> > >Oh, nice! Still have a controller chip in there though, huh. > >Wiring... I'm not sure; I'll have to check it more thoroughly when I get home. There were three very obvious wires, but from some YouTube vids I saw there is sometimes a fourth wire... > >I did see a very clever way to turn the hard disk platter itself into a commutator, using electrical tape, and turn the whole motor into a brushed DC motor, but that kind of defeats the purpose of a brushless DC motor. > >http://www.youtube.com/watch?v=CWx5ji_sFUw
"Big mama" was EC (electronically commutated). The back EMF provides the location. The "starter" was a "ring-around-the-rosy" shift-register "oscillator", which then got synchronized via the back EMF. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Tuesday, March 5, 2013 10:36:50 AM UTC-8, ehsjr wrote:
> On 3/5/2013 12:24 PM, mrdarrett@gmail.com wrote: > > > My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. > > > > > > Any way it can be powered by analog, discrete circuitry? > > > > Yes, but it's not worth the effort, unless the goal > > is the experimentation.
Right, that's the goal. =) I know there are cheap R/C motor controllers that control 3-phase DC motors, but... yeah. Seems like some sort of modified Astable Multivibrator should do the trick...?
On 3/5/2013 1:45 PM, mrdarrett@gmail.com wrote:
> On Tuesday, March 5, 2013 10:36:50 AM UTC-8, ehsjr wrote: >> On 3/5/2013 12:24 PM, mrdarrett@gmail.com wrote: >> >>> My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. >> >>> >> >>> Any way it can be powered by analog, discrete circuitry? >> >> >> >> Yes, but it's not worth the effort, unless the goal >> >> is the experimentation. > > > Right, that's the goal. =) I know there are cheap R/C motor controllers that control 3-phase DC motors, but... yeah. > > Seems like some sort of modified Astable Multivibrator should do the trick...? >
I did a search and found this for ~ $10.00 http://www.ebay.com/itm/30A-Brushless-Motor-Speed-Controller-RC-ESC-Parts-Y-/150463926575 Regarding the experiment - I did that a while back and found that it was touchy as all get out, very critical adjustment of the speed control pot to get it to run. As I recall, I _very_ rarely could get it to self start - I had to manually spin it to start it, and even that was difficult. Read up on brush-less motor control, it's interesting. :-) Ed
On Tuesday, March 5, 2013 10:53:50 AM UTC-8, ehsjr wrote:

...

> > Seems like some sort of modified Astable Multivibrator should do the trick...? > > > > > > > I did a search and found this for ~ $10.00 > > http://www.ebay.com/itm/30A-Brushless-Motor-Speed-Controller-RC-ESC-Parts-Y-/150463926575
Good price! Then again, I just took apart a 9-amp, 110v electric weed eater that could never hold the weed-eating spool properly, on a hunch put it on 24 VDC, and it WORKED! That is going to be fun. And of course I horrified my 10-year-old son by plugging in a C-frame fan motor directly into the outlet... wires only, no plug... ahahaha...
> Regarding the experiment - I did that a while back and found > > that it was touchy as all get out, very critical adjustment > > of the speed control pot to get it to run. As I recall, I > > _very_ rarely could get it to self start - I had to manually > > spin it to start it, and even that was difficult. > > > > Read up on brush-less motor control, it's interesting. :-) > > > > Ed
Will do, that sounds like fun! Michael
On Tuesday, March 5, 2013 10:53:50 AM UTC-8, ehsjr wrote:

...

> Read up on brush-less motor control, it's interesting. :-) > > > > Ed
Well, okay, still needs a microcontroller... http://ww1.microchip.com/downloads/en/appnotes/00857a.pdf
On 03/05/2013 01:01 PM, Jim Thompson wrote:
> On Tue, 5 Mar 2013 09:24:48 -0800 (PST), mrdarrett@gmail.com wrote: > >> My son and I took apart a dead hard drive, and salvaged the motor. Apparently it's a brushless DC motor that needs a dedicated controller. >> >> Any way it can be powered by analog, discrete circuitry? >> >> If I understand it correctly, each of the three power wires needs to be energized while the other two wires are held at ground, and the three wires take turns being powered by, what, +5V, right? >> >> Thanks, >> >> Michael > > Are there only three leads total, or is there a fourth, or a path to > case? Or maybe it's two-phase instead of three? > > Or it could be self-commutated, with the third lead as a speed sensing > output. > > Hard to say. Can you trace back thru the board it was on? > > Here's my big mama... > > http://www.analog-innovations.com/SED/BoschMotor1.jpg > > http://www.analog-innovations.com/SED/BoschMotor2.jpg > > http://www.analog-innovations.com/SED/BoschMotor3.jpg > > Three phase blower motor for Mercedes A/C system. All on one chip > except for the three big HexFET's. > > ...Jim Thompson >
IIRC HDD motors are all BLDC with back-EMF sensing. Hall sensing is great if you need good control at low speed, but HDD motors run at only one speed. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net