Advanced commissioning
6.15 Motor control
Converter with the control units CU240D-2
Operating Instructions, 04/2018, FW V4.9 SP10, A5E34262100B AF
195
6.15.1.3
Optimizing motor starting
After selection of the U/f characteristic, no further settings are required in most applications.
In the following circumstances, the motor cannot accelerate to its speed setpoint after it has
been switched on:
●
Load moment of inertia too high
●
Load torque too large
●
Ramp-up time p1120 too short
To improve the starting behavior of the motor, a voltage boost can be set for the U/f
characteristic at low speeds.
Setting the voltage boost for U/f control
The inverter boosts the voltage corresponding to the starting currents p1310 … p1312.
Figure 6-38 The resulting voltage boost using a linear characteristic as example
Preconditions
●
Set the ramp-up time of the ramp-function generator to a value 1 s (< 1 kW) … 10 s
(> 10 kW), depending on the power rating of the motor.
●
Increase the starting current in steps of ≤
5%. Excessively high values in p1310 ... p1312
can cause the motor to overheat and switch off (trip) the inverter due to overcurrent.
If message A07409 appears, it is not permissible that you further increase the value of
any of the parameters.
Procedure
1.
Switch on the motor with a setpoint of a few revolutions per minute.
2.
Check whether the motor rotates smoothly.
3.
If the motor does not rotate smoothly, or even remains stationary, increase the voltage
boost p1310 until the motor runs smoothly.
4.
Accelerate the motor to the maximum speed with maximum load.
