Control Structure Closed Loop (Pi); Local (Hand On) And Remote (Auto On) Control - Danfoss VLT DriveMotor FCP 106 Design Manual

Product Overview

2.3.2 Control Structure Closed Loop (PI)

2 2
The internal controller allows the frequency converter to become a part of the controlled system. The frequency converter
receives a feedback signal from a sensor in the system. It then compares this feedback to a setpoint reference value and
determines the difference, if any, between these 2 signals. It then adjusts the speed of the motor to correct this difference.
For example, consider a pump application controlling the speed of a pump to ensure a constant static pressure in a pipe.
The desired static pressure value is supplied to the frequency converter as the setpoint reference. A static pressure sensor
measures the actual static pressure in the pipe and supplies this data to the frequency converter as a feedback signal. If the
feedback signal is greater than the setpoint reference, the frequency converter reduces speed to reduce the pressure. In a
similar way, if the pipe pressure is lower than the setpoint reference, the frequency converter automatically speeds up to
increase the pump pressure.
Reference
Feedback
Illustration 2.14 Closed-loop Controller
While the default values for the closed-loop controller often provide satisfactory performance, the control of the system can
often be optimized by adjusting the closed-loop controller parameters.

2.4 Local (Hand On) and Remote (Auto On) Control

Operate the frequency converter manually via the local
control panel (LCP) or remotely via analog/digital inputs or
fieldbus.
Start and stop the frequency converter pressing the [Hand
On] and [Off/Reset] keys on the LCP. Set-up is required:
•
Parameter 0-40 [Hand on] Key on LCP.
•
Parameter 0-44 [Off/Reset] Key on LCP.
•
Parameter 0-42 [Auto on] Key on LCP.
Reset alarms via the [Off/Reset] key or via a digital input,
when the terminal is programmed to Reset.
Hand
on
Illustration 2.15 LCP Control Keys
18
®
VLT
+
S
-
*[-1]
20-81 PI
Normal/Inverse
control
Auto
O Reset
on
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DriveMotor FCP 106/FCM 106
100%
0%
PI
100%
-100%
Local reference forces the configuration mode to open
loop, independent of the setting in parameter 1-00 Configu-
ration Mode.
Local reference is restored at power-down.
Scale to
To motor
speed
control
P 4-10 P 4-19
Motor speed
Max output
direction frequency (Hz)
MG03M202