The good stuff I miss by not being a regular participant... I feel
lucky I caught this thread:
On Sun, 27 Feb 2005 23:36:30 -0500, Jerry Avins <jya@ieee.org> wrote:
>James Kennedy wrote:
>> For a state-of-the-art example, see here:
>> http://www.tip.csiro.au/Machines/success/sc.html
>>
>> It's >98% efficiency, and they've even got a thermal model so Jerry can
>> work out how to change the rating :) A downside of this type of motor
>> (ironless) is the really low inductance, which makes the power
>> electronics difficult.
>
>The shape of the design is reminiscent of printed servo motors of 20 or
>30 years ago. (No surprise. Does PMI still exist) Google shows no
>"Printed Motors Inc", but there is "PML FlightLink Ltd (Formerly Printed
>Motors Ltd)". Oh, well!
The "printed motors" concept sounds familiar. A few months back I
saw this Slashdot story:
http://science.slashdot.org/article.pl?sid=04/11/25/1331227
which points to this story of a "Microgenerator:"
http://www.gatech.edu/news-room/release.php?id=490
If you click on the pic links, specifically the one labeled "300
dpi JPG = 1.42 MB", you get a pic of these things, about one-inch
diameter PCB patterns of three-phase "windings" with six pads for
connections. This is activated by a spinning magnet over the traces,
and the magnet will allegedly be driven by a tiny turbine being
developed at another university, and the whole thing will allegedly
power laptops and cellphones of the future.
While I'm posting vaguely-related things, here's another webpage I
recently stumbled across:
http://www.otherpower.com/17page1.html
> Jerry Avins wrote:
>
>> The shape of the design is reminiscent of printed servo motors of 20
>> or 30 years ago. (No surprise. Does PMI still exist) Google shows no
>> "Printed Motors Inc", but there is "PML FlightLink Ltd (Formerly
>> Printed Motors Ltd)". Oh, well!
>
>
> Yes, it's possible to make these motors with standard PCB techniques
> (usually, multiple boards stacked togther) but the copper density just
> isn't enough for the higher performance designs. They're good for
> 'cheap' though.
>
> FYI, the CSIRO motor I linked to is *not* cheap, and sold for around
> $10k or so - but that price seems to be acceptable for solar cars...
>
> Even more OT, it's interesting to note that one of those motors (1.8kW
> i.e. toaster power levels) is enough to run a solar car at well over
> 100km/h (65mph).
Most cars have much more power than they need, anyway. When starting, I
can throw so much weight to the rear that my front-wheel-drive breaks
traction on dry pavement. With 110 hp*, that was hard to to. With 135, I
have to be careful not to. Even so, my station wagon gets to 60 mph*
from a standing start in 11 seconds with 4 passengers and 100 lbs of
tools. Ads for cars with double that horsepower and more leave me
wondering who's nuts. On the road, most of those overpowered vanity
buggies end up in my way.
Jerry
______________________________________
* Lower case!
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by James Kennedy●February 28, 20052005-02-28
Jerry Avins wrote:
> The shape of the design is reminiscent of printed servo motors of 20 or
> 30 years ago. (No surprise. Does PMI still exist) Google shows no
> "Printed Motors Inc", but there is "PML FlightLink Ltd (Formerly Printed
> Motors Ltd)". Oh, well!
Yes, it's possible to make these motors with standard PCB techniques
(usually, multiple boards stacked togther) but the copper density just
isn't enough for the higher performance designs. They're good for
'cheap' though.
FYI, the CSIRO motor I linked to is *not* cheap, and sold for around
$10k or so - but that price seems to be acceptable for solar cars...
Even more OT, it's interesting to note that one of those motors (1.8kW
i.e. toaster power levels) is enough to run a solar car at well over
100km/h (65mph).
--
James Kennedy
Electronics Design Engineer
Tritium Pty Ltd
Brisbane, Australia
Reply by Jerry Avins●February 28, 20052005-02-28
James Kennedy wrote:
> Jerry Avins wrote:
>
>> That's simple: just change the rating!
>
>
> For a state-of-the-art example, see here:
> http://www.tip.csiro.au/Machines/success/sc.html
>
> It's >98% efficiency, and they've even got a thermal model so Jerry can
> work out how to change the rating :) A downside of this type of motor
> (ironless) is the really low inductance, which makes the power
> electronics difficult.
The shape of the design is reminiscent of printed servo motors of 20 or
30 years ago. (No surprise. Does PMI still exist) Google shows no
"Printed Motors Inc", but there is "PML FlightLink Ltd (Formerly Printed
Motors Ltd)". Oh, well!
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by James Kennedy●February 27, 20052005-02-27
Jerry Avins wrote:
> That's simple: just change the rating!
For a state-of-the-art example, see here:
http://www.tip.csiro.au/Machines/success/sc.html
It's >98% efficiency, and they've even got a thermal model so Jerry can
work out how to change the rating :) A downside of this type of motor
(ironless) is the really low inductance, which makes the power
electronics difficult.
--
James Kennedy
Electronics Design Engineer
Tritium Pty Ltd
Brisbane, Australia
Reply by Jerry Avins●February 26, 20052005-02-26
Tim Wescott wrote:
...
> to-mah-to, to-may-to -- the motor itself sees AC, so implying it isn't a
> bad thing.
Always. But the fan on your CPU connects to a DC power supply with the
two wires coming out of it, and a commutator-and-brush motor's armature
coils also see AC.
> The two big differences between steppers and brushless motors is that in
> a stepper cogging is a good thing vs. brushless motors where it's
> undesirable, and steppers are generally designed with enough winding
> resistance to happily withstand being energized without moving where
> your average high-performance brushless would be dripping copper if you
> gave it rated voltage in stall.
That's simple: just change the rating!
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Tim Wescott●February 26, 20052005-02-26
Jerry Avins wrote:
> Tim Wescott wrote:
>
>> Jerry Avins wrote:
>>
>>> Richard Owlett wrote:
>>>
>>>> Jerry Avins wrote:
>>>>
>>>>> knheman206 wrote:
>>>>>
>>>>>> help!i need to program a DSPTMS320LFA) using C for a bRUSHLESS DC
>>>>>> motor. [snip]
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> DSP or not DSP, do you know enough about brushless motors to write
>>>>> a description of how to drive one? You'll more likely succeed if
>>>>> you do.
>>>>>
>>>>
>>>> Never having heard of a "brushless _DC_ motor", I went to Google.
>>>> The descriptions reminded me of stepper motors.
>>>>
>>>> Is there an intrinsic difference?
>>>> How did "DC" end up in the name?
>>>
>>>
>>>
>>>
>>> It's exactly like a stepper except for causes the steps. In a
>>> stepper, steps are commanded by a controller that sets the rate. In a
>>> brushless DC motor, the steps are determined by the rotor position,
>>> usually sensed by Hall-effect devices. Another way to look at that
>>> structure is as a permanent-magnet motor with an electronic, not a
>>> brush, commutator. It's a motor. It runs off DC*. What would you call
>>> it?
>>>
>> I would call it a permanent-magnet synchronous motor -- but the world
>> calls them "brushless DC" so that's what I call them.
>
>
> "Permanent-magnet synchronous motor" applies equally to steppers.
> "Synchronous motor" implies AC. ("Slo-Syn" s originally applies to a
> low-speed synchronous motor: 72 RPM at 60 Hz that, with a simple change
> of winding impedance, happens to make a dandy stepper.) Were I to search
> for a better name, I would probably settle on "solid-state-commutated
> motor"
>
> Jerry
to-mah-to, to-may-to -- the motor itself sees AC, so implying it isn't a
bad thing.
The two big differences between steppers and brushless motors is that in
a stepper cogging is a good thing vs. brushless motors where it's
undesirable, and steppers are generally designed with enough winding
resistance to happily withstand being energized without moving where
your average high-performance brushless would be dripping copper if you
gave it rated voltage in stall.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply by Jerry Avins●February 26, 20052005-02-26
Tim Wescott wrote:
> Jerry Avins wrote:
>
>> Richard Owlett wrote:
>>
>>> Jerry Avins wrote:
>>>
>>>> knheman206 wrote:
>>>>
>>>>> help!i need to program a DSPTMS320LFA) using C for a bRUSHLESS DC
>>>>> motor. [snip]
>>>>
>>>>
>>>>
>>>>
>>>> DSP or not DSP, do you know enough about brushless motors to write a
>>>> description of how to drive one? You'll more likely succeed if you do.
>>>>
>>>
>>> Never having heard of a "brushless _DC_ motor", I went to Google.
>>> The descriptions reminded me of stepper motors.
>>>
>>> Is there an intrinsic difference?
>>> How did "DC" end up in the name?
>>
>>
>>
>> It's exactly like a stepper except for causes the steps. In a stepper,
>> steps are commanded by a controller that sets the rate. In a brushless
>> DC motor, the steps are determined by the rotor position, usually
>> sensed by Hall-effect devices. Another way to look at that structure
>> is as a permanent-magnet motor with an electronic, not a brush,
>> commutator. It's a motor. It runs off DC*. What would you call it?
>>
> I would call it a permanent-magnet synchronous motor -- but the world
> calls them "brushless DC" so that's what I call them.
"Permanent-magnet synchronous motor" applies equally to steppers.
"Synchronous motor" implies AC. ("Slo-Syn" s originally applies to a
low-speed synchronous motor: 72 RPM at 60 Hz that, with a simple change
of winding impedance, happens to make a dandy stepper.) Were I to search
for a better name, I would probably settle on "solid-state-commutated motor"
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Tim Wescott●February 26, 20052005-02-26
Jerry Avins wrote:
> Richard Owlett wrote:
>
>> Jerry Avins wrote:
>>
>>> knheman206 wrote:
>>>
>>>> help!i need to program a DSPTMS320LFA) using C for a bRUSHLESS DC
>>>> motor. [snip]
>>>
>>>
>>>
>>> DSP or not DSP, do you know enough about brushless motors to write a
>>> description of how to drive one? You'll more likely succeed if you do.
>>>
>>
>> Never having heard of a "brushless _DC_ motor", I went to Google.
>> The descriptions reminded me of stepper motors.
>>
>> Is there an intrinsic difference?
>> How did "DC" end up in the name?
>
>
> It's exactly like a stepper except for causes the steps. In a stepper,
> steps are commanded by a controller that sets the rate. In a brushless
> DC motor, the steps are determined by the rotor position, usually sensed
> by Hall-effect devices. Another way to look at that structure is as a
> permanent-magnet motor with an electronic, not a brush, commutator. It's
> a motor. It runs off DC*. What would you call it?
>
I would call it a permanent-magnet synchronous motor -- but the world
calls them "brushless DC" so that's what I call them.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply by Jack Klein●February 26, 20052005-02-26
On Fri, 25 Feb 2005 06:58:03 -0600, "knheman206"
<knheman206@yahoo.com> wrote in comp.dsp:
> help!i need to program a DSPTMS320LFA) using C for a bRUSHLESS DC motor. I
> know basic C commands, but i dont know anything about DSP PRORAMMING!!any 1
> know a site that has helpful tuts in C language to write code for PWM and
> using capture of dsp???? I AM USING CODE COMPOSER STUDIO FOR DSP
> PROGRAMMING.
>
> i need to see some kind of code for the functioning of a PWM and an
> CAPTURE, ADC. Plzzzzzzzz if anyone has done this kind of thing b4, i would
> reallly appreciate yr help!
> thanks
> REGARDS.
> (knheman206@yahoo.com)
>
> (urgent)(urgent)
As others have already said, TI has a large number of application
notes available for their DSPs. For the 2407, start at:
http://focus.ti.com/docs/prod/folders/print/tms320lf2407a.html
On the other hand, I have serious doubts whether you can do 3-phase
motor control on these parts in C.
Running the space vector modulation algorithm in C on a 2812 at
140MHz, with the interrupt service routines running from zero wait
state internal RAM takes more than 20 microseconds worse case, when
the profile generator, velocity and position control loops have to run
as well as the transformations and the current control loop.
That's fine for running a 20KHz loop with 50 microseconds in between
interrupts.
But with a 40 MHz 2407, with its less "C friendly" instruction set, it
is quite possible that the generated code would not be fast enough
unless you reduced the control loop rate or had very simple
requirements.
I am especially concerned that the use of a phrase like "I know basic
C commands" might mean that you really don't know enough about writing
highly efficient C, tailored to the compiler and the underlying
instruction set of the processor/DSP, to manage it.
In any case, on the TI page above and other places on their web sites,
you will be able to find complete source code for this in assembly
language. To write efficient enough C to do the job in that language,
if it is possible as all, means you will need a very thorough
understanding of the assembly language anyway.
But in the end, if it is necessary to do this in C, you might need to
change to the more powerful 28xx family.
--
Jack Klein
Home: http://JK-Technology.Com
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