Product Overview; Control Structures; Control Structure Open Loop; Local (Hand On) And Remote (Auto On) Control - Danfoss VLT Micro Drive FC 51 Design Manual

Product Overview

3 Product Overview

3.1 Control Structures

3 3
Select the configuration mode in parameter 1-00 Configuration Mode.

3.1.1 Control Structure Open Loop

Reference
handling
Remote
reference
Auto mode
Hand mode
Local
reference
scaled to
Hz
LCP Hand on,
off and auto
on keys
Illustration 3.1 Open-loop Structure
In the configuration shown in Illustration 3.1,
parameter 1-00 Configuration Mode is set to [0] Open loop.
The resulting reference from the reference handling system
or the local reference is received and fed through the ramp
limitation and speed limitation before being sent to the
motor control. The output from the motor control is then
limited by the maximum frequency limit.
3.1.2 Local (Hand On) and Remote (Auto
On) Control
The frequency converter can be operated manually via the
local control panel (LCP) or remotely via analog/digital
inputs or fieldbus. If allowed in parameter 0-40 [Hand on]
Key on LCP, parameter 0-44 [Off/Reset] Key on LCP, and
parameter 0-42 [Auto on] Key on LCP, it is possible to start
and stop the frequency converter by pressing the [Hand
On] and [Off/Reset] keys. Alarms can be reset via the [Off/
Reset] key. After pressing the [Hand On] key, the frequency
converter goes into hand mode and follows (by default)
the local reference set using the LCP potentiometer (LCP
▲ ▼
12) or [ ]/[ ] (LCP 11). The potentiometer can be disabled
using parameter 6-80 LCP Potmeter Enable. If the potenti-
ometer is disabled, use the navigation keys for adjusting
reference.
After pressing the [Auto On] key, the frequency converter
goes into auto mode and follows (by default) the remote
reference. In this mode, it is possible to control the
18
®
VLT Micro Drive FC 51
P 4-14
Motor speed
high limit [Hz]
Remote
Reference
Local
P 4-12
Motor speed
low limit [Hz]
Danfoss A/S © 01/2016 All rights reserved.
100%
P 3-4* Ramp 1
P 3-5* Ramp 2
0%
Ramp
100%
-100%
frequency converter via the digital inputs and RS485. See
more about starting, stopping, changing ramps and
parameter set-ups, and so on, in parameter group 5-1*
Digital Inputs or parameter group 8-5* Serial Communi-
cation.
Hand Off
On Reset
Illustration 3.2 LCP Control Keys
Local reference forces the configuration mode to open
loop, independent on the setting of 1-00 Configuration
Mode.
Local reference is restored at power-down.

3.1.3 Control Structure Closed Loop

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 error, if any, between
these 2 signals. It then adjusts the speed of the motor to
correct this error.
To motor
control
P 4-10
Motor speed
direction
Auto
On
MG02K402