Till now i have an experience with DC& brushless permanent magnet
motors in servo applications.
I'm looking for information about AC motors ,frequency inverter and
motion control system with such components.

Particularly im looking for answers for these questions:

1) When should I prefer using AC motor and when brushless motors?
2) What are the benefits of each system?
3) What are the differences between the AC motors types? ( induction,
universal, permanent magnet etc...) when should I use each one?
4) What is the difference between synchronous and un-synchronous
motor? Which suit for which application?

Thank you
Eli

Wow! What a question. To answer those requires a university degree. I
suggest a library and 6 mos. of research as a start.
Steve

"elitkh" wrote in message
ups.com...
Till now i have an experience with DC& brushless permanent magnet
motors in servo applications.
I'm looking for information about AC motors ,frequency inverter and
motion control system with such components.

Particularly im looking for answers for these questions:

1) When should I prefer using AC motor and when brushless motors?
2) What are the benefits of each system?
3) What are the differences between the AC motors types? ( induction,
universal, permanent magnet etc...) when should I use each one?
4) What is the difference between synchronous and un-synchronous
motor? Which suit for which application?

Thank you
Eli

maybe i didn't explain myself... i'm an electronice engineer with
specialization of robotics and control.
i'm looking for books or website with theoretical information and
calculation.
thank you
eli

maybe i didn't explain myself... i'm an electronice engineer with
specialization of robotics and control.
i'm looking for books or website with theoretical information and
calculation.
thank you
eli

Great answer, steve. Maybe you've sent a troll on his way.

Bob Swinney
"Steve Lusardi" wrote in message
...
Wow! What a question. To answer those requires a university degree. I
suggest a library and 6 mos. of research as a start.
Steve

"elitkh" wrote in message
ups.com...
Till now i have an experience with DC& brushless permanent magnet
motors in servo applications.
I'm looking for information about AC motors ,frequency inverter and
motion control system with such components.

Particularly im looking for answers for these questions:

1) When should I prefer using AC motor and when brushless motors?
2) What are the benefits of each system?
3) What are the differences between the AC motors types? ( induction,
universal, permanent magnet etc...) when should I use each one?
4) What is the difference between synchronous and un-synchronous
motor? Which suit for which application?

Thank you
Eli

Potential new RCM troll sez: " maybe i didn't explain myself... i'm an
electronice engineer with
specialization of robotics and control."

Oh! OK, sorry! If you have qualifications as ""electronice engineer"" then
you should already have access to the information you seek and you could
tell us all about it.

Bob (on troll patrol this week) Swinney

"elitkh" wrote in message
oups.com...
i'm looking for books or website with theoretical information and
calculation.
thank you
eli

"elitkh" wrote in news:1139737772.529327.23790
@o13g2000cwo.googlegroups.com:

Till now i have an experience with DC& brushless permanent magnet
motors in servo applications.
I'm looking for information about AC motors ,frequency inverter and
motion control system with such components.

Particularly im looking for answers for these questions:

1) When should I prefer using AC motor and when brushless motors?
2) What are the benefits of each system?
3) What are the differences between the AC motors types? ( induction,
universal, permanent magnet etc...) when should I use each one?
4) What is the difference between synchronous and un-synchronous
motor? Which suit for which application?

Thank you
Eli


Probably better to post this question over on sci.engr.control.

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

On 12 Feb 2006 01:49:32 -0800, "elitkh" wrote:

Till now i have an experience with DC& brushless permanent magnet
motors in servo applications.
I'm looking for information about AC motors ,frequency inverter and
motion control system with such components.

Particularly im looking for answers for these questions:

1) When should I prefer using AC motor and when brushless motors?
2) What are the benefits of each system?
3) What are the differences between the AC motors types? ( induction,
universal, permanent magnet etc...) when should I use each one?
4) What is the difference between synchronous and un-synchronous
motor? Which suit for which application?

Thank you
Eli

Those are excellent questions. They are also rather comprehensive
questions of scope far broader than newsgroup responses can begin to
deal with. You need to visit a library or a bookstore. If the
latter, bring about $300 with you. You have some studying to do.

In article . com,
says...
OK...OK

lets start again and focused the questions:
1) When should I prefer using AC motor and when brushless motors?

What do you mean by "AC motor?" Most motors that you'll see referred to
as AC servos are the same thing that other mfrs will call brushless
motors. Most brushless motors are essentially permanent magnet
synchronous 3 phase motors. Baldor uses the terms interchangeably...
http://www.baldor.com/products/servo...sm_cseries.asp

Or by AC servo do you mean a system that uses an induction motor and,
for example, a vector drive to control the motor?

Ned Simmons

AC-induction motor-controling by frequency inverter
for example-is it possible to use such motor in position close loop?
thank you
eli

"elitkh" wrote in message
ups.com...
AC-induction motor-controling by frequency
inverter
for example-is it possible to use such motor in
position close loop?
thank you
eli

http://www.sew-eurodrive.ca/3_produc...y-inverter.asp

Yes, it is. If you go to the SEW web site above,
you will find that they can supply the entire
system including motor with attached position
feedback encoder built into the housing ( it fits
behind the fan) and frequency inverter. I've used
them in the past with good results. One of their
machines that they display at trade shows is a
conveyor driven by this set up. It spends all day
moving back and forth between two set
positions.Accuracy is pretty good but I can't give
you actual numbers on it.

Tom

In article . com,
says...
AC-induction motor-controling by frequency inverter
for example-is it possible to use such motor in position close loop?
thank you
eli


Yes, this machine I built about a year ago uses an induction motor, a
Yaskawa V/Hz (not vector) VFD, and a PLC to position the gantry. The
commanded position and the encoder are the inputs to a PID function in
the PLC, which in turn generates a pulse train that the VFD reads as a
velocity command. The tradeoff is that the system is not as stiff and
does not respond as quickly as a more conventional servo, but it does
settle to within about .015" of commanded position from 20 inches/second
with very little overshoot, with is more than adequate in this
application.

http://www.suscom-maine.net/~nsimmons/news/Washer01.jpg

Ned Simmons

Ned Simmons writes:

http://www.suscom-maine.net/~nsimmons/news/Washer01.jpg

Let me guess ... it's an automatic car wash for R/C model cars?

In article ,
says...
Ned Simmons writes:

http://www.suscom-maine.net/~nsimmons/news/Washer01.jpg

Let me guess ... it's an automatic car wash for R/C model cars?


Pretty close. It degreases a small medical component. Two ultrasonic
baths and four cascading rinse baths of DI water, all heated. The
gripper that handles the parts baskets could easily be adapted to pick
up model cars g.

Ned Simmons

can you pls tell me why you decide to use induction motor and not
permanent magnet brushless motor?
thank you
eli

In article , Ned Simmons
says...

... this machine I built about a year ago uses an induction motor, a
Yaskawa V/Hz (not vector) VFD, and a PLC to position the gantry. The
commanded position and the encoder are the inputs to a PID function in
the PLC, which in turn generates a pulse train that the VFD reads as a
velocity command. The tradeoff is that the system is not as stiff and
does not respond as quickly as a more conventional servo, but it does
settle to within about .015" of commanded position from 20 inches/second
with very little overshoot, with is more than adequate in this
application.

http://www.suscom-maine.net/~nsimmons/news/Washer01.jpg

Wow. Why did you go with an induction motor rather than, say, a
stepper motor? I can see that your approach could give a lot of
power and a pretty high slew rate though.

Jim


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==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
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In article .com,
says...
can you pls tell me why you decide to use induction motor and not
permanent magnet brushless motor?
thank you
eli



Money. The PLC, which was required to run the rest of the machine in any
case, was capable of controlling the VFD/induction motor, but a separate
motion controller would also have been needed for a servo amp/brushless
motor system.

In this case the drive was small enough that the difference in cost
between a servo amp/brushless motor and the VFD/induction motor probably
wouldn't have been that great - perhaps $200-$300. In a larger system
the induction motor would have a much greater economic advantage, if the
reduced performance is acceptable.

I have noticed recently that some drives manufacturers are putting specs
on the response time of even their lower end VFDs in the data sheets,
which leads me to believe that more folks are using them in closed loop
applications.

Also see my reply to Jim Rozen.

Ned Simmons

In article , says...
In article , Ned Simmons
says...

... this machine I built about a year ago uses an induction motor, a
Yaskawa V/Hz (not vector) VFD, and a PLC to position the gantry. The
commanded position and the encoder are the inputs to a PID function in
the PLC, which in turn generates a pulse train that the VFD reads as a
velocity command. The tradeoff is that the system is not as stiff and
does not respond as quickly as a more conventional servo, but it does
settle to within about .015" of commanded position from 20 inches/second
with very little overshoot, with is more than adequate in this
application.

http://www.suscom-maine.net/~nsimmons/news/Washer01.jpg

Wow. Why did you go with an induction motor rather than, say, a
stepper motor? I can see that your approach could give a lot of
power and a pretty high slew rate though.


Before I actually tried it, I wasn't sure how well the control scheme
would work. Using an induction motor, the fallback was to have the PLC
control the VFD with three set speeds - slew, slow and creep - that
would allow zeroing in on the desired position. I've done that before
and it can work surprisingly well, but the programming is much messier
than just plugging in a predefined PID function. The fallback wouldn't
have been practical with a stepper.

A few other things drove the choice:

The load is constant and almost purely inertial.

The motor was available off the shelf inexpensively with a right angle
hollow shaft reducer, which made the interface to the linear slide very
easy and clean.

It's very quiet. The only perceptible noise is that of the linear
bearings.

I don't usually like steppers, though save for the gear reducer, this
would have been an OK app for a stepper. My usual objection to steppers
is that servos are only marginally more expensive and offer better
performance.

Ned Simmons

In article , Ned Simmons
says...

I don't usually like steppers, though save for the gear reducer, this
would have been an OK app for a stepper. My usual objection to steppers
is that servos are only marginally more expensive and offer better
performance.

Thank you. We've been using a lot of stepper motors at work in
precision control applications, where a servo setup would not work.
But yours is a nice approach to controlling what could potentially
be a lot of hp in a very precise way.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

is it right to say:
1) induction system is cheaper then brushless system (with the same
capability)?
2) brushless motor is stronger then induction motor (in the same size)?
3) brushlees system more suit for position application?

eli

In article .com,
says...
is it right to say:
1) induction system is cheaper then brushless system (with the same
capability)?

If by capability you mean power, I'd say yes, especially in larger
systems.

2) brushless motor is stronger then induction motor (in the same size)?

Yes, that's a pretty safe generalization.

3) brushlees system more suit for position application?

If maximum stiffness and response are requirements, yes.

Ned Simmons

In article , says...
In article , Ned Simmons
says...

I don't usually like steppers, though save for the gear reducer, this
would have been an OK app for a stepper. My usual objection to steppers
is that servos are only marginally more expensive and offer better
performance.

Thank you. We've been using a lot of stepper motors at work in
precision control applications, where a servo setup would not work.
But yours is a nice approach to controlling what could potentially
be a lot of hp in a very precise way.


Your welcome. That system is pretty well documented, let me know if
you'd like any details.

I'm curious about what sort of app you've got where a stepper
outperforms a servo. The only thing I can think of off the top of my
head would be a situation where the load inertia is unpredictable.

Ned Simmons

In article , Ned Simmons
says...

I'm curious about what sort of app you've got where a stepper
outperforms a servo. The only thing I can think of off the top of my
head would be a situation where the load inertia is unpredictable.

It's a precision thing. We have an RF isolations screen room, with
stepper motors operating non-metalic shafts that penetrate the wall.

We use them to control voltages inside the screen room to a high
degree of accuracy by operating ten turn pots. With a fine and
a coarse mode, we can get 1 part in 10e6 stability and control. The
nice thing is that if the power goes out, nothing loses its place.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================