We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control. I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

On Sat, 14 Jun 2008 05:45:19 -0500, "RogerN"
wrote:

We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control. I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

Sensorless vector gives better speed regulation than Volts-Hertz, but
less than 3 Hz is too slow for good torque with an induction motor.
Sounds like you need a servo motor or if this is continuously low
speed consider a gear reducer.

My first drive was flux vector on a 50 Hp. drive (closed loop speed
feedback). That gave pretty good low speed torque, which was required
in the application (extruder), but I sure didn't operate all the time
at low speed.

Pete Keillor

Most industrial motor manuf. offer a line of VFD rated motors with
provision
for mounting a tach or position encoder on the back end of the motor.
One

My CHNC needed encoder feedback on the 7.5 hp 3phase spindle for a VFD with
encoder feedback. I mounted the standard 3phase motor on the mill table,
turned it on reverse from the right angle adaptor in the spindle. bored a
perfect on center hole just a scosh under size of the pin I drove in. Then
mounted a USdigital encoder. Werks Grate.

To run that slow you'd also need to mount a cooling fan because the motor's
fan will run too slow to help.

Karl


Karl

On Sat, 14 Jun 2008 05:45:19 -0500, "RogerN"
wrote:

We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control.

no ****.

change the pulleys to reflect a better torque range at that low speed
and run the drive at a higher speed.


I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

not that low.


You are going to have to find a happy medium between your maximum rpm
and your minimum rpm and change pulleys to reflect that ratio

Or put in a 2 speed gear box


Gunner



at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
* * * * * * *mariposa rand mair theal

This is a machine our companies German owners crammed down our throat that
was supposed to be running by the end of March. The first thing I thought
of was changing the gear ratio and speeding up the motor but since it's not
complete and not turned over to us, we have to get the stubborn Germans to
agree to everything. I thought if it would do any good I could sneak and
enable the sensorless vector control without them knowing, if it would do
any good. I guess I thought if it could give 100% torque at zero rpm, it
should give 100% torque at 1, 2, or 3rpm, I guess not.

This is for a weighing system that doses out chemical for rubber mixing and
a dose could be from 0.07lbs to 20lbs all with an accuracy of 1% or 3g,
whichever is greater. It has a coarse dosing and fine dosing, it's
difficult to run slow enough to hit the target on smaller weights and be
able to run fast enough to dose 20lbs in ~ 13seconds with 1% accuracy, all
with a drive programmed for 60hz. But what do Americans know, they have
"superior German Engineering". Also, we wanted Allen Bradley Controls but
Siemens was crammed down our throat. Now we're busting our butts trying to
help them get it to run...

They just discovered the low speed torque boost settings, and are going to
show me how to enable it. They don't know that I already did it for some of
the stations (35 in all).

Thanks

Roger N

"Gunner Asch" wrote in message
...
On Sat, 14 Jun 2008 05:45:19 -0500, "RogerN"
wrote:

We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control.

no ****.

change the pulleys to reflect a better torque range at that low speed
and run the drive at a higher speed.


I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

not that low.


You are going to have to find a happy medium between your maximum rpm
and your minimum rpm and change pulleys to reflect that ratio

Or put in a 2 speed gear box


Gunner



at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
mariposa rand mair theal

On Sat, 14 Jun 2008 19:13:11 -0500, "RogerN"
wrote:

This is a machine our companies German owners crammed down our throat that
was supposed to be running by the end of March. The first thing I thought
of was changing the gear ratio and speeding up the motor but since it's not
complete and not turned over to us, we have to get the stubborn Germans to
agree to everything. I thought if it would do any good I could sneak and
enable the sensorless vector control without them knowing, if it would do
any good. I guess I thought if it could give 100% torque at zero rpm, it
should give 100% torque at 1, 2, or 3rpm, I guess not.

This is for a weighing system that doses out chemical for rubber mixing and
a dose could be from 0.07lbs to 20lbs all with an accuracy of 1% or 3g,
whichever is greater. It has a coarse dosing and fine dosing, it's
difficult to run slow enough to hit the target on smaller weights and be
able to run fast enough to dose 20lbs in ~ 13seconds with 1% accuracy, all
with a drive programmed for 60hz. But what do Americans know, they have
"superior German Engineering". Also, we wanted Allen Bradley Controls but
Siemens was crammed down our throat. Now we're busting our butts trying to
help them get it to run...

They just discovered the low speed torque boost settings, and are going to
show me how to enable it. They don't know that I already did it for some of
the stations (35 in all).

Thanks

Roger N


at those speeds...even stepper motors would be better....3 hz??????

gunner


"Gunner Asch" wrote in message
.. .
On Sat, 14 Jun 2008 05:45:19 -0500, "RogerN"
wrote:

We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control.

no ****.

change the pulleys to reflect a better torque range at that low speed
and run the drive at a higher speed.


I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

not that low.


You are going to have to find a happy medium between your maximum rpm
and your minimum rpm and change pulleys to reflect that ratio

Or put in a 2 speed gear box


Gunner



at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
mariposa rand mair theal


at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
* * * * * * *mariposa rand mair theal

On Sat, 14 Jun 2008 19:13:11 -0500, "RogerN"
wrote:

This is a machine our companies German owners crammed down our throat that
was supposed to be running by the end of March. The first thing I thought
of was changing the gear ratio and speeding up the motor but since it's not
complete and not turned over to us, we have to get the stubborn Germans to
agree to everything. I thought if it would do any good I could sneak and
enable the sensorless vector control without them knowing, if it would do
any good. I guess I thought if it could give 100% torque at zero rpm, it
should give 100% torque at 1, 2, or 3rpm, I guess not.

This is for a weighing system that doses out chemical for rubber mixing and
a dose could be from 0.07lbs to 20lbs all with an accuracy of 1% or 3g,
whichever is greater. It has a coarse dosing and fine dosing, it's
difficult to run slow enough to hit the target on smaller weights and be
able to run fast enough to dose 20lbs in ~ 13seconds with 1% accuracy, all
with a drive programmed for 60hz. But what do Americans know, they have
"superior German Engineering". Also, we wanted Allen Bradley Controls but
Siemens was crammed down our throat. Now we're busting our butts trying to
help them get it to run...

They just discovered the low speed torque boost settings, and are going to
show me how to enable it. They don't know that I already did it for some of
the stations (35 in all).

Thanks

Roger N

Man, I feel your pain. I work for a multinational (these statements
are my opinions, and mine alone, not those of my employer, etc.), and
run into the Siemens-ABB mafia (EU is better) regularly. The only
"user friendly" features of Siemens software usually got added because
of howls of protest from US Siemens employees. However, I have enough
experience, years, and rep to get listened to occasionally, so the two
control projects I'm currently doing are Allen-Bradley.

You've got a speed range requirement of 285:1 if the charge time is
held constant. That's a hell of a lot more than the normal 10:1
turndown to which I limit my stuff. If the coarse dosing and fine
dosing have a built in 30:1 rate difference independent of speed, it
ought to be doable, but just barely. Your minimum speed should be 6
Hz or higher.

Another gotcha is a low speed de-rating algorithm. On Allen-Bradley
Powerflex drives, the default is to start de-rating the current
capacity at 20% speed or below. After a couple minutes, the VFD will
trip at normal loads. I usually disable this one since my small
inverter duty motors are mostly TENV anyway.

Good luck.

Pete Keillor




"Gunner Asch" wrote in message
.. .
On Sat, 14 Jun 2008 05:45:19 -0500, "RogerN"
wrote:

We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control.

no ****.

change the pulleys to reflect a better torque range at that low speed
and run the drive at a higher speed.


I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

not that low.


You are going to have to find a happy medium between your maximum rpm
and your minimum rpm and change pulleys to reflect that ratio

Or put in a 2 speed gear box


Gunner



at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
mariposa rand mair theal