View Full Version : VFD: Automatic torque boost?

Doc Nickel
03-03-2011, 08:27 PM
I'm installing another VFD, and going through the book as I get ready to wire some controls. This particular VFD is a WEG, and the first time I've used this brand.

The various parameters that can be programmed include something called "Automatic Torque Boost". The default setting is zero.

If I understand this correctly, I'm presuming it adds extra voltage if/when it senses the motor bogging down (change in RPM.) Is this correct? And more to the point, do I want to use it, and if so, what percentage should I set it at?

I'll be using this VFD to power my Arboga gearhead drill press. I will on occasion want as much low-end grunt as I can get, as I want to be able to dial it down to 80-ish RPM (roughly 50% frequency in low gear and on the motor's low range) or even a little lower, for big drills in steel and/or holesaws.


03-03-2011, 09:54 PM
Torque boost applies at start-up -- it boosts the voltage/frequency ratio (i.e., increases the voltage) for increased starting torque.

On my VFD's, it won't apply voltage past the rated voltage (which would also be the rated speed if V/f = 1.0 as usual).

03-04-2011, 12:05 PM
I'm much more familiar with tuning closed loop servos than VFD's, but that sounds like a fancy marketing term for feed forward gain. Adding it should help maintain velocity as the load changes. In a servo application, we typically start at 100% and back off from there if the overshoot is excessive. It all depends on your load so you will have to play with it. Maybe start at 0 and work your way up.

03-04-2011, 12:42 PM
i assume you use your vfd in vector drive. are you sure "automatic torque boost" applies to this mode? i think not.