Bias Frequencies

Does anyone happend to know what exactly Bias Frequencies are for in a VFD.

I am not sure about bias but the carrier/switching frequency is the sqaurewave that the VFD generates. The sinsuoidal wave the motor sees is produced from that squarewave.

This may help: http://www.patchn.com/what_is_a_drive.html

In addition to what Ron mentioned, there are also a few other frequencies, but I haven't heard them called bias frequencies.

There can be a minimum frequency, which you set to the minimum friquency at which the motor will turn. This prevents the control system from trying to "creep" the motor at a speed too low for it to even move.

There can also be a "skip" frequency or band, which will prevent the VSD operating in a chosen frequency band. This is primarily to prevent resonance in your machine components. Some machines have a natural frequency in a component or structure within the normal 0-120Hz operating range of the typical VSD. If the VSD operates at this frequency, the results can be interesting.

Hopefully one of these is what you want.

I am frequently told that I am biased towards blue eyed brunettes....

Thanx!!!

I was thinking it was the first one Doug had mentioned about the minimum frequency. But I just wanted to make sure because the manual was very vauge on what bias frequency was. But when we changed the value that was the minimum frequency it ran at. Thanks all for your input.

base frequancy

High voltage
IS it bias frequancy or bias frequancies?
if it is more then one may be it's the skip.
As all mentioned above i didn't here about the bias frequancy.But there is the base frequancy at which the drive output it's maxiumum voltage to the motor.
Would you please tell us which brand of VFD you are using?
BR

bias is used when tracking two or more drives so the speed is the same from a low rpm to max rpm. the bias offsets the mid range. for example. speed pot 10% = drive one 100 rpm drive two 100 rpm. speed pot 100% drive one = 1750 rpm drive two = 1750 rpm. if the mid range speed is off, say speed pot 50% drive one 950 rpm drive two 800 rpm you can adjust the bias in drive two to boost to the same rpm.
make sure you check the speed range more than once for proper tuning.
hope it helps
Lynn