When using droop control to balance the torque across multiple motors driving a coupled mechanical load such as a chain conveyor, what is the actual variable that is being altered by each drive? From what I understand, at rated conditions the output of each drive is altered by the selected droop value (i.e. 5%) and scaled linearly to 0% at zero RPM. What I am unsure of is exactly what variable is used to instigate the % droop, is it frequency independent of voltage, or is it the combined V/F signal?
The application in question is a chain conveyor, with 30+ individual induction motors each supplied by a small scalar control converter. The type of VSD specified will depend on what speed control method is appropriate. Most likely Droop control or Speed Trimming. I am attempting to build Simulink model to showcase the use of droop to regulate the motor speeds under variable loading of the conveyor but I am unsure exactly how the output of the drive should be altered when the load torque limit is reached.
Can provide more details if necessary. Regards