INVT Goodrive 310-UL Series Operation Manual page 169

GD310-UL series VFD
Keypad setting PID given
P09.01
Keypad
(PID given source selection)
AI1
0
AI2
1
AI3
2
3
HDI
4
Multi-stage
5
speed
MODBUS 6
7
PROFIBUS
8
Ethernet
9
CAN
Simple illustration of the PID control operation and adjustment:
Proportional control (Kp): When the feedback is different from the reference, the output will be
proportional to the difference. If such a difference is constant, the regulating variable will also be
constant. Proportional control can respond to feedback changes rapidly, however, it cannot eliminate
the difference by itself. A larger the proportional gain indicates a faster regulating speed, but a too
large gain will result in oscillation. To solve this problem, set the integral time to a large value and the
differential time to 0, run the system only with proportional control, and then change the reference to
observe the difference (that is, static difference) between the feedback signal and reference. If the
static difference occurs in the direction of reference change (such as reference increase, where the
feedback is always less than the reference after system stabilizes), continue increasing the
proportional gain; otherwise, decrease the proportional gain. Repeat this process until the static
difference becomes small.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 VFD is procedure PID control.
P09.00
PID given value
P17.23
+
Given -feedback<P09.08？
-
P09.08（PID control deviation limit）
P09.02
（PID feedback source selection）
P17.24
PID feedback
value
Terminal function 25
PID control pause
Y
Keep the current
Valid
frequency
N Invalid
Kp P09.04(proportional gain)
AI1
Ti P09.05（integral time ）
0
AI2
Td P09.06（differential time）
1
2 AI3
3
HDI
4
MODBUS
5
6
PROFIBUS
7
Ethernet
CAN
-161-
Basic operation instruction
PID stop
adjustment
P09.09
（the upper limit of PID
output ）
0
1
P09.03
（the chrematistic of PID
output）
P09.10
（lower limit of PID output）
Set frequency
P17.00
PID output