Corrected from:
- i700 servo inverter V01.04.00.9125
Response of the new version:
In the case of servo control, the current controller gain can be set as high as before. Accordingly, the same motor characteristics can be achieved with regard to stability and dynamic performance.
The additional filtering of the actual current value erroneously effective in the case of servo control (ASM, SM) is no longer active.
What happens?
With the motor control modes 'Servo control - SM' and 'Servo control - ASM' (most commonly used in practical operation), the running characteristics of the motor are less stable than with the previous firmware version - when selecting the same control loop parameters, in particular the same current controller parameters.
This is due to an additinal filtering of the actual current value and the dead time in the current control loop resulting from this.
The additional filtering is actually only designed for the newly implemented motor control mode 'Sensorless servo control for synchronous motors' (0x2C00=3). Erroneously, the filtering is, however, also effective in the firmware version concerned when using servo control (SM, ASM) .
When does the problem occur?
The problem occurs when operating the i700 in the following motor control modes:
- 0x2C00=1: 'Servo control - synchronous motor (SM)'
- 0x2C00=2: 'Servo control - asynchronous motor (ASM)'
Which products are affected?
- i700 servo inverter only version V01.03.08.9047
Short-term measures/recommendations:
Reduce the control loop gain of the current controller and, if necessary, of the superimposed control loops (speed, position).
If necessary, use the previous firmware version.
Evaluation:
High dynamic performance requirements of the application may not be achieved because of a lower stability limit of the current control loop and an insufficiently dynamic setting of the current controller.
