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V/F is still vector! its used to running more than one motor at a time. V/F in not volts/hzs. For auto tuning to be usefull motor inputs have to be correct . D0-01 is model dependent and this one is lacking .Quote:
Originally Posted by Dan Friedrichs
Respectfully, I think you're misinformed about this. "V/Hz" and "V/f" are both used interchangeably to refer to a control mode where the ratio of volts to hertz (or "frequency") is constant. People often call this "scalar" control. "Vector" control does not use a fixed ratio of volts to hertz. It adjusts the voltage as needed to maximize torque.Quote:
Originally Posted by jack forsberg
Here's a good article I found that explains it:
http://machinedesign.com/motorsdrive...ol-method-vfds
Sorry, I accidentally clipped off the header at the start of those tables. The column containing the phrase "model dependent" has a header that reads "Factory setting". So they're just saying that the default value of d0-01 varies, depending on which specific model of the drive you buy. You can program d0-01 to whatever you want.
is this the part that got clipped off?Quote:
Originally Posted by Dan Friedrichs
http://i284.photobucket.com/albums/l...psrec4rjiz.jpg
So D0-01 is not capable of 200 volts even though it can be entered as a value in the setting.
there are other modes for V/F that use torque compensation that adjust the voltage as i said for more than one motor. that's why you have a function on your drive for base frequency. I did not see one place in that manual that said the the VFD in sensor less vector did not need the base set when the motor was out side the VFD input voltage. Please Inform me i am clearly confused .
I can't find that text in the version of the manual I have, but I also don't understand what you're saying. Are you saying you don't think the output voltage can go below 220VAC? That's clearly wrong - the output voltage must go down to near zero when the frequency goes to near zero.
Setting D0-01 to 200V and running in SVC mode clearly limits the output voltage to 200V. I've ran the motor up to the voltage limit, and it definitely stops increasing at 200V (as shown on the display and verified using an oscilloscope). When I change D0-01 to other values (ie - 180v, 190v, 200v, 210v), the voltage also stops increasing once it hits those values.
Torque compensation is just slightly "nudging" the constant V/Hz ratio at different speeds to give more favorable performance for a particular load curve. It still relies on a constant V/Hz ratio.
SVC does not use a constant V/Hz ratio, so setting a "base frequency" makes no sense. It won't limit the output voltage because the output voltage is not related to the base frequency!
I want to be very clear that I think you're completely correct, Jack, about how to set up a V/Hz drive to allow running a 200V motor off a 240V supply - I agree with you, entirely, there. But those are not vector drives. These new vector drives do not operate the same way.
I don't know how I missed this thread but, Jack and Don you both right. In V/H there is a constant line between volts and hurts. When your hurtz are at 50%, so are your volts. In most applications this would be OK.
In higher torque applications at lower speed/hurtz you should be using a sensorless vector mode (this is open loop).This maintains the voltage(better) and hurtz varies more. This keeps in the flux in the amateur stable with torque requirements. The motor actually works more like a DC motor.
On a drill press that is drilling metal and I am running a 1.5" drill bit at 45 RPM with power feed of .005 per revolution i'd like to know my horse power is up there. This would be applicable for lathes, Tablesaws running a smaller dado blade, milling machine, bandsaw... almost anything that you want the rim speed or surface speed to have constant torque.
If the VFD only has V/H at 50% hz. you have just De-rated the motor 50% of its horsepower and it is linear.
I think if you put this https://www.amazon.ca/dp/B003GUH4SC/...WHPFVFGE2RE3EK
And gave it a good pull at 800 RPM you'll see a trip.
It is definitely an interesting topic. I think running a "only" V/H inverter needs to be considered and weighed out for the application.
I can't remember the last time I changed the belt on my Delta drill press...too lazy I guess! This is pretty cool stuff, Dan. I'm an EE but lacking in 'motor' skills.... :)
See, that was my problem, too, Chris - "Set to 2k RPM? Sure, that'll probably be fine for this circle cutter ;)"Quote:
Originally Posted by Chris Padilla
More correctly, V/f (or V/Hz) pattern is the generic term for the software parameter which can be set to Open Loop Vector, Closed Loop Vector, Constant Torque, Variable Torque, Auto Torque Boost, Multi-Point V/f Custom Curve Setting, and other manufacturer specific operation modes.
Constant torque produces a linear output voltage to frequency curve that provides increased current (torque) at low speeds. Variable torque produces a non-linear curve that provides energy savings for pump and fan operation. Vector control modes monitor output current and motor speed if available and adjust output frequency and voltage to maintain the desired shaft rpm or load current.
Other than some rare, esoteric configuration, the first five parameters in the table above should reflect the motor nameplate data. Base frequency (d0-03) should be set to the synchronous speed of the motor (60Hz). The auto-tune function uses these parameters to set limits of operation and performs electrical tests that enable calculation of the motor electrical parameters.
Single or multiple-motor operation can be accomplished in most output modes, but it gets dicey in vector control mode if the number of connected motors changes considerably. (Think hot-strip steel mill cooling table with 50 motors on the same drive.)
As an aside Dan, I would be careful about running your control and power cables is such close proximity. Your manual may specify precautions. Locating low voltage signal cables and motor output cables together is a big no-no. VFD input cables are less noisy, but can occasionally be problematic.
Interesting factoid: Tektronix consulted with our company for the development of the PWM triggering functionality in the classic PS 222 portable scope.
As a time out from the discussion I am enjoying, I wanted to say, Dan you did a really nice, clean install! I just surface mount the VFD anywhere that seems convenient but it always feels half done... for a week then I move onto other projects.
BTW no offense as these discussions are useful and interesting to me but those that are only considering VFD for 3 phase woodworking machines might should steer clear it is easy to get the impression it takes a EE with concentration in motor theory to take advantage of VFDs where the reality is for our needs only the basic functionality is needed and you won't need to track down your neighborhood EE nor pay the local teenaged hacker to get you up and running with the correct amount of electrons running the correct direction and riding the sine roller coaster on the correct track. Again not suggesting it shouldn't be discussed, as it should be, but just some words to hopefully avoid scaring the bejeebus out of someone.
I don't even know what mine it set to, Dan, but I've run EVERYTHING at that RPM. You may have just piqued my curiosity enough to look but I bet I'll forget when I get home.... LOL :DQuote:
Originally Posted by Dan Friedrichs
Very nicely done Dan! That enclosure doesn't appear to be NEMA, how does someone determine if they need a NEMA enclosure or the VFD can survive in the shop conditions without?
Nice setup, but my understanding of 200V motors is that they are rated that so that they can be run continuously on 208, 230 or 240V. Over-voltage isn't a problem for most motors, but under-voltage (without current control) is.
Thanks Dan! Perfect timing for me as my single phase DP motor just quit. I'd like to go the 3 phase/VFD route for variable speed as well. I plan to purchase the same VFD you have. When I go to purchase the 3 phase motor, does it really matter what speed/rpm I get?
Looks like a NEMA 1 enclosure to me.
Quote:
Originally Posted by Bill Adamsen
I'm not sure it really matters. You'll need to outfit it with a pulley, so by sizing that (and choosing which step on the other pulley), it seems like you could adjust for different motor speeds. My impression is that 1725rpm might be a better choice just given the relative pulley sizes you have to deal with.Quote:
Originally Posted by Mike Brucker