Lenze 8400 - Optimising Field Feedforward Control and Torque Feedforward Control

5 Motor control (MCTRL)
5.7 Sensorless vector control (SLVC)
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Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
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5.7.4.7 Optimising field feedforward control and torque feedforward control
At the start of an acceleration process and at the end of a deceleration process, the field current
(nReaktCurrentId_a) may oscillate.
• Especially when accelerating via small acceleration ramps, these oscillations become obvious by
the speed being unable to follow the setpoint or speed drops during acceleration.
• Oscillating can be reduced by increasing the gain of the field current controller in C00985
. A
small increase of the cross current controller gain in C00986
can further improve the starting
performance for small acceleration ramps.
In the field weakening range, the cross current (nEffCurrentIq_a) may oscillate when an acceleration
process starts or a deceleration process ends.
• In case of some motors, this cross current oscillation (nEffCurrentIq_a) can also occur in the
motor setting range/field weakening range transitions which may also cause an overcurrent
interruption.
• These oscillations can be reduced by again increasing the cross current controller gain slightly
in C00986
.
 Note!
The setting of C00985 and C00986 reduces the torque setting range.