Which products are affected?
9300 vector 0.37…90 kW SW V7.1
Applications
Applications in which a regenerative energy occurs, e. g. fans.
Function description
In order to avoid steep current rises after re-enabling the pulse after an OU message various measures have been applied inside the software. Especially in case of powers ranging from
110 to 400 kW OC1 trips have occurred repeatedly. The function extensions have been applied to the complete power range (0.37…400 kW):
- If the DC-bus voltage (UDC) exceeds the switch-off threshold OU the pulse inhibit is set and an OU message is indicated. At the same time an internal timing element is started for a decay time (C0912). The pulse inhibit and the OU message are deactivated when the voltage falls below the switch-on threshold OU and if the decay time has expired. If necessary, the decay time has to be prolonged by means of C0912. The decay time in [ms] is set under code C0912. The Lenze setting can be changed by factor 0.5…2.
- The ramp function generators in the function blocks NSET and RFG1 are stopped during the pulse inhibit caused by OU.
- When the pulses are re-enabled after an OU message the output current of the drive controller is slowly increased along a linear ramp.
The Lenze setting of the decay time C0912 results from the double rotor time constant TR which is calculated as follows:
C0912[ms] = TR[ms] * 2 = 2 * Stator inductance C0092 in [mH] / Rotor resistance C0082 in [Ohm]
When current overshoots occur after the pulse inhibit has been re-enabled it may be useful to increase the current controller gain (C0075) and to reduce the integral action time (C0076).
Fig. 1: Influence of decay time (C0912)
1) Switch-off threshold OU
2) Switch-on threshold OU
A) The time between exceeding the switch-off threshold OU and falling below the switch-on threshold OU is equal to or larger than the decay time set under C0912. The pulse inhibit is deactivated when the voltage falls below the switch-on threshold OU.
B) The time between exceeding the switch-off threshold and falling below the switch-on threshold is shorter than the decay time set under C0912. The pulse inhibit is deactivated when the decay time under C0912 has expired.
