INVT Goodrive 35 Series Operation Manual page 233

inverters Basic operation instruction
Goodrive35
gain, vice versa. Repeat the action until the static error achieves a little value.
Integral time (Ti): the output adjustment will accumulate if there is an error between the feedback and
the reference. The adjustment will keep on increasing until the error disappears. If the error is existent
all the time, the integration adjustor can cancel the static error effectively. Vibration may occur as a
result of unstable system caused by repeated over-adjustment if the integration adjustor is too strong.
The features of this kind of vibration are: the fluctuating feedback signal (around the reference) and
increasing traverse range will cause vibration. Adjust the integral time parameter from a big value to a
little one to change the integral time and monitor the result until a stable system speed is available.
Derivative time (Td): when the error between the feedback and the reference, a proportional
adjustment will be output. The adjustment only depends on the direction and value of the error
change other than the error itself. The derivation adjustment controls the change of feedback signals
according to the changing trend when it fluctuates. Because the derivation may enlarge the
interference to the system, especially the frequent-changing interference, please use it carefully.
When P00.06, P00. 07=7 or P04.27=6, the running mode of the inverter is procedure PID control.
7.15.1 General steps of PID parameters setting:
a Ensure the gain P
When ensure the gain P, firstly cancel the PID integration and derivation (set Ti=0 and Td=0, see
the PID parameter setting for detailed information) to make proportional adjustment is the only
method to PID. Set the input as 60%~70% of the permitted Max. Value and increase gain P from 0
until the system vibration occurs, vice versa, and record the PID value and set it to 60%~70% of
the current value. Then the gain P commission is finished.
b Ensure the integral time Ti
After ensuring the gain P, set an original value of a bigger integral time and decrease it until the
system vibration occurs, vice versa, until the system vibration disappear. Record the Ti and set the
integral time to 150%~180% of the current value. Then integral time commission is finished.
c Ensure the derivative time Td
Generally, it is not necessary to set Td which is 0.
If it needs to be set, set it to 30% of the value without vibration via the same method with P and Ti.
d Commission the system with and without load and then adjust the PID parameter until it is
available.
7.15.2 PID inching
After setting the PID control parameters, inching is possible by following means:
Control the overshoot
Shorten the derivative time and prolong the integral time when overshoot occurs.
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