V/f operation and voltage boost: Motor may turn back during reversing (corrected from V2.10.12)
Corrected from: i700 servo inverter, series devices (V02.x): from V02.10.12.11906
existing devices (V01.x): from V01.10.12.11905
Response of the new version:
When coming to standstill, the motor shaft no longer turns back.
What happens?
When the voltage boost is activated, the motor shaft may slightly turn back when coming to standstill. The severity of the 'turn-back' depends on the boost setting, and the characteristics of motor and load.
When does this behaviour occur?
- The behaviour occurs if the motor is operated in V/f characteristic control (0x2C00=6) and
- the voltage boost is used instead of the current boost (minimum current control, Imin) selected in the Lenze setting.
Which products are affected? i700 servo inverter
Short-term measures:
Use the current boost as provided for in the Lenze setting instead of the voltage boost.
Evaluation/recommendations: Lenze recommends using the current boost to ensure an adequate magnetisation of the asynchronous motor in V/f operation in the lower speed range. For this, a specified minimum current (Imin) will be injected by means of voltage vector control. This method is much more efficient and accurate than simply increasing voltage by means of the voltage boost.
