Emerson EV1000-2S0004G User Manual page 53

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Reference
(F5.08 and F5.10)
Where:
KP proportional gain; Ki: integral gain. In Fig. 5-30,
refer to F5.01~F5.15 for the definitions of
close-loop reference, feedback, error limit and
proportional and Integral parameters.
There are two features of internal PI:
The relationship between reference and feedback
can be defined by F5.08~F5.11.
For example: In Fig. 5-2828, if the reference is
0~10V analog signal, the expected controlled
value is 0~1MP, and the pressure signal is
4~20mA, then the relationship between reference
and feedback is shown in Fig. 5-31.
Feedback
20mA
4mA
0
Fig. 5-31 Reference (Input) and Feedback
The reference value is based on 10V (i.e. 10V
means 100% input); and the feedback value is
based on 20mA (20mA corresponds to 100%
output).
Close-loop characteristic is selected through
F5.16 to satisfy different applications.
In order to meet the control requirements, the
motor's speed should be increased with reference
speed. This kind of control characteristic is called
positive response. If the motor speed is required
to be decreased when the reference value is
+
ε
Reference
regulation
-
Fig. 5-30 PI Working Mechanism
Reference
10V
EV1000 Series General Purpose Variable Speed Drive User Manual
Error limit
Regulation
(F5.16)
(F5.15)
Feedback
regulation
(F5.09 F5.11)
increased, this control characteristic is called
negative response.
See Fig. 5-32. F5.16 defines the two
characteristics.
Speed
Fig. 5-32 Close-loop Control Characteristics
After the system type is determined, the following
procedures can be used to determine the close
loop parameters:
Determine the close-loop reference and
feedback channel(F5.01 and F5.02);
Define the relationship between
close-loop reference and feedback value
(F5.08~F5.11);
Determine the speed reference of speed
close-loop control and the number of
revolutions of PG (F5.06~F5.07);
Determine the close-loop regulation
characteristic, that is, if the motor speed
decreases while the input reference
increases, then the close-loop control
characteristic should be set to negative
(F5.16=1);
Set integral regulation and close-loop
frequency (F5.17～F5.19);
Adjust close-loop filter time, sampling
Chapter 5 Parameters
ε
KP ×
(F5.12)
+
Output
+
ε
Ki ×
∑
(F5.13)
Feedback
Positive
Negative
Close loop
reference
49