Lars Andersson wrote:
> My thought was to not run PWM but only direct switching at a base frequency
> of a few kHz and without any sensing of rotor angle.
> The rotor will run well once it is locked in to the rotating field from the
> stator. Crude, but it works.
>
Old drives use a 6-step drive
> 100K / 60 * 2(poles) = electrical rpms. You'll need to run the pwm
> well over 100Khz to do this. The lowly dspic33f mc motor series will
> struggle to do this, let alone any additional processing.
My thought was to not run PWM but only direct switching at a base frequency
of a few kHz and with
On 25 February 2012 10:15, andy pugh wrote:
> The back-emf in any particular field winding will be independent of
> the current, but the field windings which are driven by the H-bridge
> at any one time will be different between a properly commutated bldc
> with a 90 degree phase shift and one be
On 25 February 2012 02:55, Jon Elson wrote:
>> The effect of this is (I think) that the back-emf is very small, and
>> the current very high, for a given torque.
>>
> HUH? On a permanent magnet motor, the back EMF is determined entirely by
> the magnets, and will be the same with or without driv
andy pugh wrote:
> It will probably start from rest, certainly with a soft-starting VFD,
> and will run synchronously.
> However, running synchronously the phase lead will depend only on
> load, and will be very small. The field will be almost 100% direct and
> zero quadrature.
> The effect of this
Of course, if you use hall effect sensors it would be easier. Some folks
add hall effect sensors to outrunners, it works fine.
On Fri, Feb 24, 2012 at 1:08 PM, andy pugh wrote:
> On 24 February 2012 17:30, Lars Andersson wrote:
>
> > You can run a BLDC from a dumb fixed frequency three phase s
On 24 February 2012 17:30, Lars Andersson wrote:
> You can run a BLDC from a dumb fixed frequency three phase supply if only
> you can get it to spin in the first place.
It will probably start from rest, certainly with a soft-starting VFD,
and will run synchronously.
However, running synchronous
100K / 60 * 2(poles) = electrical rpms. You'll need to run the pwm well
over 100Khz to do this. The lowly dspic33f mc motor series will struggle to
do this, let alone any additional processing.
I think there is something else though, it seems that a bldc has less
torque from a fixed frequency tha
While 10 RPM is pretty impressive mechanicalvise, it is only 1700 Hz on
a two-pole motor. A BLDC is similar to a syncronous three phase motor that
was used much for really high power apps in ancient times, maybe even today.
Typical example is a city water supply pump. They had to be brought up
I doubt any vfd would handle high rpms anyway. I think you would need to
stay with a 2 pole for those rpm's, or you would have to have a pretty
fancy driver. Bldc's aren't the right wave shape for vfds.
On Thu, Feb 23, 2012 at 7:46 PM, Kirk Wallace
wrote:
> On Thu, 2012-02-23 at 20:10 +, an
On Thu, 2012-02-23 at 20:10 +, andy pugh wrote:
... snip
> Can you? I thought they were brushless?
They are.
> A VFD will rotate them, but the phase lead will be about zero, so the
> efficiency will be awful.
Maybe that's why it didn't work when I tried using a VFD on a normal
brushless moto
On Thu, 2012-02-23 at 20:10 +, andy pugh wrote:
> On 23 February 2012 19:56, Kirk Wallace wrote:
>
> > If I where to stick with an outrunner solution, one thing comes to mind,
> > I could get a kit and wind the motor for 220 and use a VFD.
>
> Can you? I thought they were brushless?
> A VFD
Another advantage of inrunners is that you can directly cool the stator
which is where you're generating all the heat. On bigger motors (Im
talking from forktruck/golfcar motor size experience), DC armatures had a
similar problem (as outrunners). You're dumping a lot of heat into
something thats
On 23 February 2012 21:04, Lars Andersson wrote:
> For PCB milling on the other hand with carbide bits of 0.3 mm dia or so you
> cannot get to much RPM really, 50-100 000 RPM is desirable to get a decent
> cutting speed. This is not what outrunners are optimised for. You would be
> better off wit
It has been mentioned in this thread already, but I think it can be
clarified.
Outrunners when they appeared were a blessing for the R/C plane builder,
since a propeller wants to run at speeds below 10 000 RPM for best efficency
and earlier motors did maybe 20-30 000 RPM so they had to be geared.
On 23 February 2012 19:56, Kirk Wallace wrote:
> If I where to stick with an outrunner solution, one thing comes to mind,
> I could get a kit and wind the motor for 220 and use a VFD.
Can you? I thought they were brushless?
A VFD will rotate them, but the phase lead will be about zero, so the
ef
On Thu, 2012-02-23 at 20:14 +0100, Peter Georgi wrote:
> Hi Kirk, saw that you are strugling for outrunners for model air planes,
> cars or boats. Look at http://www.hobbyking.com/hobbyking/store/index.rc for
> quite good and afordable motors and ESC's. The number of rpm's depend on the
> type of m
r [mailto:eekel...@psu.edu]
Gesendet: Donnerstag, 23. Februar 2012 00:22
An: Enhanced Machine Controller (EMC)
Betreff: Re: [Emc-users] Outrunners
On Wed, Feb 22, 2012 at 4:34 PM, andy pugh wrote:
>
> Bear in mind that cooling might be inadequate without a huge propellor
> on the front, so
On Wed, Feb 22, 2012 at 4:34 PM, andy pugh wrote:
>
> Bear in mind that cooling might be inadequate without a huge propellor
> on the front, so expect to derate.
>
> RC cars use inrunners with heat sinks, so air must not be an absolute
requirement. Probably a good idea though
Eric
--
On Wed, 2012-02-22 at 16:02 -0600, James Louis wrote:
> You might want to check out this site:
>
> http://www.logicnc.com/home.html
>
> They have a parallel port to rc servo converter so LinuxCNC can control an
> outrunner spindle speed.
> Cheers,
> Jim
This is what I've done with RC so far:
ht
PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Outrunners
You could take a look at the marine applications (inrunners), there are
some water cooled. What will your supply be? You'll want to decide what
rpm you want to run, as the higher kv, the lower the torque. Are you
On Wed, 2012-02-22 at 16:18 -0500, Erik Friesen wrote:
> You could take a look at the marine applications (inrunners), there are
> some water cooled. What will your supply be? You'll want to decide what
> rpm you want to run, as the higher kv, the lower the torque. Are you going
> to belt drive,
On 22 February 2012 20:48, Kirk Wallace wrote:
> I want to mount an outrunner (or other) to a NMTB40 tool holder to try
> some circuit board routing.
Bear in mind that cooling might be inadequate without a huge propellor
on the front, so expect to derate.
--
atp
The idea that there is no such t
You could take a look at the marine applications (inrunners), there are
some water cooled. What will your supply be? You'll want to decide what
rpm you want to run, as the higher kv, the lower the torque. Are you going
to belt drive, or direct drive some way?
On Wed, Feb 22, 2012 at 3:58 PM, Cl
Le 22.02.2012 21:48, Kirk Wallace a écrit :
> I want to mount an outrunner (or other) to a NMTB40 tool holder to try
> some circuit board routing. I like the outrunner form because it looks
> like the motors seem shorter for the same power. I haven't flown model
> planes for over twenty years so I'
I want to mount an outrunner (or other) to a NMTB40 tool holder to try
some circuit board routing. I like the outrunner form because it looks
like the motors seem shorter for the same power. I haven't flown model
planes for over twenty years so I've lost my feel for sizes and
capacities. Does anyon
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