Flying restart circuit, MCTRL-NACT (C0051) deviates from current motor speed
Which products are affected?
9300 vector 0.37…90 kW SW ≤ V6.3
What happens?
The MCTRL-NACT signal (actual speed) deviates from the current motor speed.
When does the problem occur?
If the flying restart circuit (C0142 = 2 or 3) is activated it is connected to a coasting machine after controller enable. This is done by determining the current machine speed by means of a search process. Since the current machine speed is not known at first the search speed is indicated at the MCTRL-NACT output (actual speed) during the search process. As soon as the current machine speed has been determined and controls the machine again, the actual motor speed is indicated at MCTRL-NACT again.
Possible diagnostics?
Check whether the drive controller executes a flying restart circuit during the deviation:
check if the flying restart is activated by C0142 = 2 or 3
and if the controller has been inhibited before.
Short-term measures/recommendations?
None.
Evaluation:
Since the current machine speed is not known during the search process, MCTRL-NACT cannot be indicated correctly. Up to now, the search speed has been indicated in order to enable the user to easily understand the search process by means of an oscilloscope. However, in case of one application the customer was irritated with regard to the evaluation of the signal in the control by the display of the search speed under MCTRL-NACT.
Figure: Signal sequence when executing a flying restart circuit
CH1: (pink) Current motor speed read in via DFIN for display purposes (this signal is usually not available during commissioning)
CH2: (red) MCTRL-IACT
CH3: (blue) MCTRL-NACT
CH4: (turqoise) MCTRL-NSET2
