Concentricity-improvement of asynchronous motors

Question:

How can the concentricity behaviour of asynchronous motors at the 9300 servo inverter be improved?

Answer:

A better concentricity of asynchronous motors can be realized via the function block input 'MCTRL-FLD-WEAK' of function block 'MCTRL-Motor control'. Via this function block input the control parameters can be influenced within the motor control.
The default setting of the 'FLD-WEAK' function block is 100 %. The engagement with a free code digit (FCODE) can reduce the value by some percent even when the contoller is enabled. The resulting field weakening causes smoother drive behaviour and consequently a better concentricity.

For this selection please consider:

• Eventually the total torque will not be available anymore, if the value at the function block input 'FLD-WEAK' is modified.
• With usage of field weakening the field current reduces. The motor compensates, however, the reduced torque by a higher torque generating current in order to obtain the required motor torque. Thus, the apparent motor current can rise and the drive's heating increases. The drive selection must allow such an 'additional loading'; otherwise the controller's monitoring will be activated due to the overtemperature.

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