How accurate torque limit function of VFD?
How accurate torque limit function of VFD?
(OP)
Can someone tell me how accurate the torque limit functions of a voltage source VFD is? In other words, can one be sure that the motor output torque will never be exceeded (even for ms or so)? In a specific case, we are looking at a 4-Q MV GTO drive with an Active Frond End (GTO's) with a torque limit set to 140%.
Thanks for your feedback.
Thanks for your feedback.






RE: How accurate torque limit function of VFD?
The torque step response is generally better than two milliseconds if you have an IGBT inverter with a few kHz carrier frequency. Your GTO has a much lower carrier frequency - it might not even be vector controlled - so you really should ask the manufacturer.
RE: How accurate torque limit function of VFD?
RE: How accurate torque limit function of VFD?
The essential question is: Can one rely on the electronic torque limit function of the VFDs or is it still necessary to size the mechanical equipment (couplings/reducers/shafts) according to the available torque of the motors which can be 220% or more.
RE: How accurate torque limit function of VFD?
The torque loop is always closest to the motor (inside the speed loop) in modern vector drives. External torque limiters that act on the speed loop output (like those you could see in some DC servos te nor twenty years ago) do not exist today. And if they do, they shouldn't.
So, if you use AB, ABB, Danaher, Siemens, Schneider etc and there is a paramater called "max torque" or "torque limit" or similar wording, you can trust that the set limit will be kept under all circumstances. A hardware failure that produces a higher torque has yet to be "invented". In DC drives, almost all hardware failures seemed to be able to produce excessive torque. Not so in AC vector drives.
RE: How accurate torque limit function of VFD?
"Venditori de oleum-vipera non vigere excordis populi"
RE: How accurate torque limit function of VFD?