July 2013 6.8 The control loop 867
The step response is adjusted such that there is no overshoot and the rise
time is as small as possible:
In MP2420.x, define the P factor of the current controller.
Automatic calculation of the P factor for synchronous and asynchronous
motors is also possible. However, automatic calculation is not to be used for
linear synchronous and torque motors.
The calculated value is entered in the MP file. An * is appended to the
calculated value to show that the parameter was determined automatically.
In MP2430.x, define the I factor of the current controller.
Automatic calculation of the I factor for synchronous and asynchronous
motors is also possible. However, automatic calculation is not to be used for
linear synchronous and torque motors.
The calculated value is entered in the MP file. An * is appended to the
calculated value to show that the parameter was determined automatically.
MP2420.x P factor of the current controller
Input: 0 to 9999.99 [V/A]
* = automatic calculation of the P factor
MP2430.x I factor of the current controller
Input: 0 to 9 999 999 [Vs/A]
* = automatic calculation of the I factor
In addition, the function of the current controller is monitored automatically. If
the fault-free functioning of the current controller is not ensured, the brake of
the respective drive is activated immediately and an emergency stop error
message is triggered. This happens if the speed controller specifies the
maximum current, but the actual current remains zero.
Expanded current
controller
bandwidth
For axes with rigidly connected mechanics it may make sense to adjust the
current control loop using the maximum possible bandwidth to attain high
gains in the superimposed velocity control loop. For the CC 61xx controller
unit there are two procedures for increasing the bandwidth of the current
control loop:
Using machine parameter MP2450 to increase the controller factors in the
current control loop,
and proportionally differentiating feedforward (D feedforward) to optimize
the command action of the current control loop (MP2440).
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