i950 230V units: Default setting of the current limiting controller (Imax) leads to oscillation tendency in the range of max. output voltage

Corrected from:
Servo Inverter i950 FW: from V01.08.xx (in planning)
 
Response of the new version:
 
 
What happens?
Under the conditions mentioned below, an increased oscillation in the motor current can occur with some asynchronous motor types.

When does the behaviour occur?
  • Motor control mode V/f characteristic control and
  • Operation at the voltage limit (transition to field weakening) and at the maximum current limit.
Which products are affected?
Servo Inverter i950 (230V unit, 1-phase or 3-phase)
 
Short-term measures / Evaluation / recommendations:
Background: For the i950 units in the 230V unit version, the default settings of the current limiting controller (Imax controller) are selected too dynamically for some motor types.

As a short-term measure, the settings of the Imax controller can therefore be adjusted as follows:
  • Imax controller dynamics (0x2B02): Prevents interaction between the voltage and current limitation in the field weakening range and thus avoids oscillation in the motor current.
  • Reduce the Imax controller gain (0x2B02:1) by half, and
  • Increase Imax controller reset time (0x2B02:2) by a factor of 2.
The behaviour described has so far only occurred when operating Lenze servo asynchronous motors in the V/f characteristic control motor operating mode.

Automatic Translation

URL for linking this AKB article: https://www.lenze.com/en-de/go/akb/202000008/1/
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