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http://www.astromec.com/faq.htm#Question%2012I'm wondering if anyone knows of a site, explaining brushless dc
motors - their design and and how they work.
or just grab a cheap 12 VDC muffin fan and look at it. Windings in theI'm wondering if anyone knows of a site, explaining brushless dc
motors - their design and and how they work.
OK, I have a spare cpu fan, so I took that, and looked at it.On Sat, 11 Sep 2004 05:44:37 GMT, George <spamproofemail@here.com
wrote:
I'm wondering if anyone knows of a site, explaining brushless dc
motors - their design and and how they work.
or just grab a cheap 12 VDC muffin fan and look at it. Windings in the
center, a Hall effect switch to flip polarity, and a "refigerator
magnet" strip inside the rotating hub.
So in other words, this is all to make the electric motor both"George" <spamproofemail@here.com> wrote in message
news:nge6k0l0ar815ubhngib5j624dk7h4pd29@4ax.com...
OK, I have a spare cpu fan, so I took that, and looked at it.
I guess the tiny resistor-looking thing is something to do with the
hall effect unit. It's that hall thing I want to learn more about,
as I want to build a much larger version of one of these motors.
I believe now, having seen this small example, that the seam in the
rotor magnet is what triggers the sensor. If so, that's pretty cool.
Sensors are old hat. Modern speed controllers (eg for Permanant magnet
brushless DC model aircraft motors) don't need them anymore. If you have a
motor with say three windings then at any one time only two are powered. The
third winding is used to sense rotor position (the controller looks for the
zero crossing). The tricky problem is how to get the motor to start in the
right direction and all the speed controller manufacturers have their own
tricks for that. Essentially it involves pulling the rotor to a known
position then applying a rotating field (but it's much more complex than
that).
OK, I have seen the otherpower.com site, and plan to peruse in much"George" <spamproofemail@here.com> wrote in message
news:aam6k093je3o5t56or8a0t1rdk0t000heb@4ax.com...
So in other words, this is all to make the electric motor both
brushless, and at the same time, to make the motor start rotating,
when the switch is flicked, and not let the electric motor stall in
the field, and consequently burn out?
The sensors have been a source of problem to model flyers (particularly on
high power competition systems operating at 1400W+). The sensor has to be in
the right place w.r.t the coils and any error in the sensor detecting the
position of the rotor results in a timing error. At high powers there is a
lot of noise about and if the sensor triggers at the wrong time it's
possible to blow up all the FETs in the controller. Sensorless systems have
proven more reliable.
My little project will be a little brushless generator driven via
pulley attached to small engine, or human power. So, can my
generator be brushless? I suspect it can, and would like the simplest
example a diagram for such a brushless circuit. It doesn't really
have to be b/less, but I'd rather do it that way, if it's 'simple
enough'.
Try contacting the author of this site...
http://www.otherpower.com/otherpower_wind_alternators.html
See under "Brushless DC PM Servo Motors"
Colin
Thats to improve efficiency by reducing eddy currents in the core (see alsoWhy the stacked metal plates, and not a single solid core?