Control Structures; Control Principle - Danfoss VLT Design Manual

Introduction

2.8 Control Structures

2.8.1 Control Principle

2 2
Illustration 2.11 Control Structures
The frequency converter is a high performance unit for
demanding applications. It can handle various kinds of
motor control principles such as VVC
normal squirrel cage asynchronous motors.
2.8.2 Control Structure Open Loop
Illustration 2.12 Open Loop Structure
In the configuration shown in Illustration 2.12, 1-00 Configu-
ration 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.
20
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VLT Refrigeration Drive Design Guide
Short circuit behavior on this frequency converter depends
on the 3 current transducers in the motor phases.
plus
and can handle
In 1-00 Configuration Mode it can be selected if open or
closed loop is to be used
2.8.3 Local (Hand On) and Remote (Auto
The frequency converter can be operated manually via the
local control panel (LCP) or remotely via analog/digital
inputs or serial bus.
If allowed in 0-40 [Hand on] Key on LCP, 0-41 [Off] Key on
LCP, 0-42 [Auto on] Key on LCP, and 0-43 [Reset] Key on LCP,
it is possible to start and stop the frequency converter
byLCP using the [Hand On] and [Off] keys. Alarms can be
reset via the [Reset] key. After pressing the [Hand On] key,
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MG16G102 - VLT is a registered Danfoss trademark
On) Control