Eliminated from:
Inverter Drives 8400 StateLine, HighLine and TopLine from firmware version 12.00.00.00
Behaviour of the new version?
During the transition from open-loop operation to closed-loop controlled operation in the SLPSM motor control mode, the current balancing processes have been optimised.
Which products are affected?
Inverter Drives 8400 StateLine, HighLine and TopLine with a firmware version lower than 12.00.00.00
What happens?
When the speed threshold set in C0996/2 for the change-over from open-loop operation to closed-loop controlled operation is exceeded, vibrations in the motor current occur, which can also result in an overcurrent error.
When does the problem occur?
When a synchronous motor starts up, which is actuated in the SLPSM motor control mode without speed feedback. The impact of the behaviour varies with regard to its intensity and depends on the control parameters set, the load condition, and the motor model.
Diagnostics options?
Comparison of the output frequency during the occurrence of the vibrations with the set transition threshold in C0996/2. If the time of the vibration excitation can be shifted with C0996/2, this indicates that the transition from open-loop control to closed-loop control is the cause.
Short-term measures/recommendations?
Usually the overshoot can be decreased by reducing the gain in the current control loop (C0075).
Evaluation:
The behaviour is typically detected during commissioning. The remedy for this is an adaptation of parameters.
