So DC motors are obsolete!

[g***@gmail.com]

Talked to a motor manufacturer in Germany. They don't even do DC motors any more, no call for them at all. Just ac and brushless DC which is really ac under a different name. Apparently with a good ac controller you can get an induction motor to have the same torque as a DC motor and you get max torque at zero speed - all down to flux vectoring. So do we throw out our brushed motors.

[b***@yahoo.ie]

'k

[Tim Wescott]

Post by g***@gmail.com
Talked to a motor manufacturer in Germany. They don't even do DC motors
any more, no call for them at all. Just ac and brushless DC which is
really ac under a different name. Apparently with a good ac controller
you can get an induction motor to have the same torque as a DC motor and
you get max torque at zero speed - all down to flux vectoring. So do we
throw out our brushed motors.

Keep what you have, at least. They'll work as well as they ever did. I
think that itty bitty brushed motors will be around for a while, at least
until people figure out how to make itty bitty controllers that are
cheaper than itty bitty brushes and commutators.

Industrial brushless motors with built-in controllers are getting more
common -- one box with a shaft on one end and a cord on the other. Give
it power and commands, and it does what it's told.

[Randy Yates]

[...]
I think that itty bitty brushed motors will be around for a while, at
least until people figure out how to make itty bitty controllers that
are cheaper than itty bitty brushes and commutators.

Too funny! Tim, was the term "itty bitty" used in your graduate
textbooks?

[Tim Wescott]

Post by Randy Yates

[...]
I think that itty bitty brushed motors will be around for a while, at
least until people figure out how to make itty bitty controllers that
are cheaper than itty bitty brushes and commutators.

Too funny! Tim, was the term "itty bitty" used in your graduate
textbooks?

No. But it should have been.

I couple of decades ago I realized, thanks to a colleague with a PhD,
that "bazzilion", "ginormous", "teeny", etc., are all valid technical
terms (meaning, in order, roughly, and in most contexcts, "so many that
it's not cost effective to enumerate", "so big that it's not cost
effective to consider the size", and "so small that it's not cost
effective to consider the size").

[e***@ieee.org]

On Fri, 12 May 2017 13:56:50 -0500, Tim Wescott

Post by Tim Wescott

Post by Randy Yates

[...]
I think that itty bitty brushed motors will be around for a while, at
least until people figure out how to make itty bitty controllers that
are cheaper than itty bitty brushes and commutators.

Too funny! Tim, was the term "itty bitty" used in your graduate
textbooks?

No. But it should have been.
I couple of decades ago I realized, thanks to a colleague with a PhD,
that "bazzilion", "ginormous", "teeny", etc., are all valid technical
terms (meaning, in order, roughly, and in most contexcts, "so many that
it's not cost effective to enumerate", "so big that it's not cost
effective to consider the size", and "so small that it's not cost
effective to consider the size").

There are measurement units that are commonly used to convey similar
meaning, .e.g., "buttloads", "shit-ton", etc. I've accepted these,
and many other, as legitimate technical terms or units of measurement
for a long time. They seem to be nearly universally accepted, so it
has been neither problematic nor controversial in my experience.





---
This email has been checked for viruses by Avast antivirus software.
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[rickman]

Post by e***@ieee.org
On Fri, 12 May 2017 13:56:50 -0500, Tim Wescott

Post by Tim Wescott

Post by Randy Yates

[...]
I think that itty bitty brushed motors will be around for a while, at
least until people figure out how to make itty bitty controllers that
are cheaper than itty bitty brushes and commutators.

Too funny! Tim, was the term "itty bitty" used in your graduate
textbooks?

No. But it should have been.
I couple of decades ago I realized, thanks to a colleague with a PhD,
that "bazzilion", "ginormous", "teeny", etc., are all valid technical
terms (meaning, in order, roughly, and in most contexcts, "so many that
it's not cost effective to enumerate", "so big that it's not cost
effective to consider the size", and "so small that it's not cost
effective to consider the size").

There are measurement units that are commonly used to convey similar
meaning, .e.g., "buttloads", "shit-ton", etc. I've accepted these,
and many other, as legitimate technical terms or units of measurement
for a long time. They seem to be nearly universally accepted, so it
has been neither problematic nor controversial in my experience.

You need to be more specific. Is that an imperial "shit-ton" or a
metric "shit-ton". The imperial "shit-ton" is an informal unit with a
definition that varies with the speaker much like the inch being related
to the distance between the user's knuckles.

[robert bristow-johnson]

Post by e***@ieee.org
On Fri, 12 May 2017 13:56:50 -0500, Tim Wescott

Post by Tim Wescott

Post by Randy Yates

[...]
I think that itty bitty brushed motors will be around for a while, at
least until people figure out how to make itty bitty controllers that
are cheaper than itty bitty brushes and commutators.

Too funny! Tim, was the term "itty bitty" used in your graduate
textbooks?

No. But it should have been.
I couple of decades ago I realized, thanks to a colleague with a PhD,
that "bazzilion", "ginormous", "teeny", etc., are all valid technical
terms (meaning, in order, roughly, and in most contexcts, "so many that
it's not cost effective to enumerate", "so big that it's not cost
effective to consider the size", and "so small that it's not cost
effective to consider the size").

There are measurement units that are commonly used to convey similar
meaning, .e.g., "buttloads", "shit-ton", etc. I've accepted these,
and many other, as legitimate technical terms or units of measurement
for a long time. They seem to be nearly universally accepted, so it
has been neither problematic nor controversial in my experience.

milli-smidgen .

[Phil Hobbs]

Post by e***@ieee.org
On Fri, 12 May 2017 13:56:50 -0500, Tim Wescott

Post by Tim Wescott

Post by Randy Yates

[...]
I think that itty bitty brushed motors will be around for a while, at
least until people figure out how to make itty bitty controllers that
are cheaper than itty bitty brushes and commutators.

Too funny! Tim, was the term "itty bitty" used in your graduate
textbooks?

No. But it should have been.
I couple of decades ago I realized, thanks to a colleague with a PhD,
that "bazzilion", "ginormous", "teeny", etc., are all valid technical
terms (meaning, in order, roughly, and in most contexcts, "so many that
it's not cost effective to enumerate", "so big that it's not cost
effective to consider the size", and "so small that it's not cost
effective to consider the size").

There are measurement units that are commonly used to convey similar
meaning, .e.g., "buttloads", "shit-ton", etc. I've accepted these,
and many other, as legitimate technical terms or units of measurement
for a long time. They seem to be nearly universally accepted, so it
has been neither problematic nor controversial in my experience.

Remember Mars Climate Orbiter and the Gimli Glider. You have to specify
if it's a metric buttload or an avordupois buttload.

Cheers

Phil Hobbs

[Steve Underwood]

Post by g***@gmail.com
Talked to a motor manufacturer in Germany. They don't even do DC motors any more, no call for them at all. Just ac and brushless DC which is really ac under a different name. Apparently with a good ac controller you can get an induction motor to have the same torque as a DC motor and you get max torque at zero speed - all down to flux vectoring. So do we throw out our brushed motors.

Brushed motors are still being used in massive numbers in new product
designs. For example, most new power tools and kitchen appliances still
use them. It isn't high cost German manufacturers who produce those low
end motors, though.

Steve

[Frank Miles]

Post by g***@gmail.com
Talked to a motor manufacturer in Germany. They don't even do DC motors any more, no call for them at all. Just ac and brushless DC which is really ac under a different name. Apparently with a good ac controller you can get an induction motor to have the same torque as a DC motor and you get max torque at zero speed - all down to flux vectoring. So do we throw out our brushed motors.

We use some specialty "zero-cogging" motors to generate precision
torque-systems - "manipulanda". These are grasped by the hand, and
the user attempts to move the device while following a kind of video
game. Unfortunately variations in torque - particularly at higher
frequencies - excite certain proprioceptors in a bad way. We need
super-smoothness as well as being able to deliver high torque
perturbations.

So yes, it's a _real_ niche application, but the loss of these motors
is gonna be hard. There is at least one maker of a fractional-turn
motor that is close to working (we haven't had to go there yet).

[h***@gmail.com]

Post by g***@gmail.com
Talked to a motor manufacturer in Germany.
They don't even do DC motors any more, no call for
them at all. Just ac and brushless DC which is really
ac under a different name. Apparently with a good ac
controller you can get an induction motor to have the
same torque as a DC motor and you get max torque at
zero speed - all down to flux vectoring. So do we throw
out our brushed motors.

There is a light rail system, a few years old now, in Seattle.

If you are anywhere near the train, with an AM radio, you
know that the train is running. The power converter puts
out enough harmonics within the AM band, which then go down
the overhead wires to any nearby radios (usually in cars).

We also have some electric trolley (two overhead wire) buses
in Seattle, with different converter technology, that also
goes into the AM band.

As far as I know AC/DC motors (series wound) are still used in
many household appliances, still cheaper than the appropriate
power converter. For tiny motors, like for battery powered
toys, I believe that they are usual DC brush motors.