51
Integral time (ti):
Determine the speed of PID regulators to do the integral adjustment of deviation.
When the feedback deviates from the set value, the output adjustment value need to continuously accumulate. And if the deviation persists, the adjustment value
continuously increases until there is no deviation. Integral regulator can validly eliminate static difference. If the integral regulator is too strong, there will be repeated
overshoot, which will make the system oscillate. Generally, the adjustment of integration time parameters is from large to small, and the integration time is gradually
adjusted, while the effect of system adjustment is observed,all until the stable speed of the system meets the requirements.
Differential time (Td):
Determine the strength of PID regulator to adjust the rate of deviation change.
When the feedback changes with the set deviation, the rate of deviation change and output become the regulating value of proportion, which is only related to the
direction and magnitude of deviation change, but has nothing to do with the direction and magnitude of deviation itself. when the feedback signal changes, the function
of derivative adjustment is to adjust according to the changing trend of it, so as to restrain the change of it. Please use derivative regulator with caution, because
derivative regulator is easy to amplify the interference of the system, especially the interference from large changing frequency.
03.06
Sampling period T
0.1
～
10.0s
0.0
The larger the sampling period, the slower the response, but the better the interference signal suppression effect, so it is generally unnecessary to set it.
03.07
Deviation limit
0.1
～
20.0%
0.0
The deviation limit is the ratio of the absolute value of the deviation between the system feedback quantity and the given quantity to the given quantity. When the
feedback quantity is within the deviation limit, the PID adjustment will not operate. As shown in the figure below, setting a reasonable deviation limit can prevent the
system from reaching the target Frequent adjustment near the value will help improve the stability of the system.
Figure 03-2 Schematic diagram of deviation limit
03.08
Closed loop preset frequency
0.0
～
upper limit frequency
0.0
03.09
Preset frequency holding time
0.0
～
999.9s
0.0
This function code defines the frequency and running time of the inverter before the PID is put into operation when PID control is valid. In some control systems, in
order to make the controlled object reach a predetermined value quickly, the inverter is set according to this function code to force a certain frequency value of 03.08
and a frequency holding time of 03.09 to be output. That is, when the control object is close to the control target, the PID controller is put in to improve the response
speed. As shown below:
Figure 03-2 Schematic diagram of closed-loop preset frequency operation
03.10
Sleep threshold coefficient
0.0
～
150.0%
100.0
