Variable Freq. Drive.
Variable Freq. Drive.
(OP)
I am trying to put together a drive system that will be able to operate at 400 to 35000 rpm. I was wondering if this can be accomplished with a VFD and if I will be able to control the lower speeds that are needed.





RE: Variable Freq. Drive.
But there are a lot of details between what you ask and what you need. If you FULLY describe what you are trying to do we can offer suggestions.
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RE: Variable Freq. Drive.
A brushless DC drive package might be the best or only alternative below some power level.
CJC
http://www.vfdriveinfo.com
RE: Variable Freq. Drive.
35 kRPM is typical compressor speed. There are companies specializing in compressors for trucks that build such drives. These speeds need some experience and knowledge to turn out right.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Variable Freq. Drive.
RE: Variable Freq. Drive.
If you can locate a speed increaser gearbox with 2/1 ratio, the motor speed drops to 17500 to 200rpm which is well within most VFD capabilities assuming a two pole special-built motor.
That won't be an easy gearbox to locate either.
I've got test cell motors running at 22,500rpm and 500hp but that's still a long way from 35000rpm.
If the kw or hp is small, you might want to check out manufacturers of woodworking spindle motors. Many of these work to 100,000rpm. There used to be a German company named Spindel that made these motors and drives.
RE: Variable Freq. Drive.
htt
They also build entire test stands if you are planning on being an end user (as opposed to a competitor).
http://reuland.com/Brochures/Dynamic%20Testing.pdf
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Variable Freq. Drive.
RE: Variable Freq. Drive.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Variable Freq. Drive.
If you mean it's running at X RPM and you move the speed setting to "Y" RPM, the motor will attempt to match the drive output, subject of course to a number of limitations.
You can, of course, juggle ramp times, etc., to lessen and shocks to the system.
old field guy
RE: Variable Freq. Drive.
RE: Variable Freq. Drive.
Assuming that he motor is able to stand the mechanical stresses, doubling RPM is going to radically increase the load. A centrifugal pump will require around four times the horsepower at twice the RPM.
old field guy
RE: Variable Freq. Drive.
There is actual hardware. And the speed changes.
Running a standard motor at 3+ kRPM is usually not a problem. But you have to check balancing and bearings to make sure.
Noticed the use of capital letters? It makes reading easier. It isn't hard to master. Just needs some training. Adding full stops and apostrophes takes a little more effort, but it's worth it in the long run.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Variable Freq. Drive.
I am thinking that the VFD put out 0 ~60 HZ regardless of the VFD frequency setting and the frequency setting requaird, so that the VFD can calculate the motor operating RPM based on the output frequency ( 0 ~60 HZ ) and make such information avliable to the user.
please let me know if I am wrong
Thanks
RE: Variable Freq. Drive.
No, in induction motors, the RPM is directly proportional to the input frequency. Therefore we have term VFD - variable FREQUENCY drive. The INPUT frequency doesn't change.
The VFD rectifies the AC input to make DC, then by means of clever electronics it chops up the DC to make the output look like AC, and it can control this "chopping" to make AC of varying frequencies.
If the drive puts out 60 HZ (US standard) then the motor will run at its 60Hz RPM. To get a different RPM, you instruct the drive to change its output frequency. The motor then runs at the RPM proportional to that frequency.
old field guy
RE: Variable Freq. Drive.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Variable Freq. Drive.
I have to make it simple. I must often talk to managers.
old field guy
RE: Variable Freq. Drive.
Mechanically, the motor needs to be able to withstand higher speeds too. If you are doubling a 4 pole motor then mechanically the motor tends to be ok as the bearing strucutres are designed for 2 pole motor speeds.
RE: Variable Freq. Drive.
I interpreted that you (Wedoca) are meaning that if you PROGRAM THE MOTOR PARAMETERS in a VFD for a higher speed than what the motor is actually designed for, is the output V/Hz pattern going to change?
If that's the question, the answer is; it depends on the drive. An older V/Hz (non-vector) drive will probably not change anything, but if the VFD display offers a scaled readout, i.e. RPM or FPM or GPM as some do, it will be incorrect. However if it is a Vector drive, open loop or closed lop, the vector algorithms are tied to a motor model and if you set the motor base speed (number of poles) incorrectly in the setup, most of the motor models will end up incorrect.
If that is not what you meant, then never mind.
And next time, please start a new thread and reference an existing thread if it is pertinent.
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: Variable Freq. Drive.
Build yourself a custom motor using an E+A rotor/staror set.
http:/
Drive it using a Delta Electronics Model VFD-VE VFD operating in Sensorless Vector Mode. This drive can output frequencies up to 3000 Hz.