Figure 6-4 Drive Operation In High Starting Torque Mode - Siemens 6SR41 series Product User Manual

The control then ramps the output from rated slip to the minimum speed limit while
maintaining rated current. At minimum speed, the control holds the speed ramp for one
second at this value, reduces the torque current (Iqs), and enables the speed loop. One
second later, the flux loop is enabled and the drive resumes acceleration to the desired
speed demand. After the flux loop has been enabled, if the drive senses that the motor flux is
low (or Ids is too high), then the drive trips on Fail to Magnetize Fault within the time set by
the Flux Ramp Time. Note that a "bump" in output voltage may be noticed when the flux loop
is enabled, since the control transitions from an open loop control to closed loop using
measured voltages and current.
When a stop command is issued, the drive ramps down normally from the operating speed
to the minimum speed settings, and then transitions to a coast stop (i.e., drive output is
disabled).
Figure 6-4 Drive Operation in High Starting Torque Mode
Product User Manual
Operating Instructions, Version AE 12/2009, A5E01454341C
Application and Operation
6.3 High Performance Control
117