Control Structures; Local (Hand On) And Remote (Auto On) Control - Danfoss VLT HVAC Basic Drive FC 101 Design Manual

Introduction to VLT® HVAC B...

2.7 Control Structures

1-00 Configuration Mode can be selected if open or closed
2 2
loop is to be used.
2.7.1 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 2.17 Open Loop Structure
In the configuration shown in Illustration 2.17, 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.
2.7.2 PM/EC+ Motor Control
The Danfoss EC+ concept provides the possibitily for using
high efficient PM motors in IEC standard frame size
operated by Danfoss frequency converters.
The commissioning procedure is comparable to the
existing one for asynchronous (induction) motors by
utilising the Danfoss VVC
Customer advantages:
•
Free choice of motor technology (permanent
magnet or induction motor)
•
Installation and operation as know on induction
motors
•
Manufacturer independent when choosing system
components (e.g. motors)
•
Best system efficiency by choosing best
components
•
Possible retrofit of existing installations
•
Power range: 0.37-90 kW (400 V) for induction
motors and 0.37-22 kW (400 V) for PM motors.
24
®
VLT HVAC Basic Drive Design Guide
P 4-14
Motor speed
high limit [Hz]
Remote
Reference
Local
P 4-12
Motor speed
low limit [Hz]
plus
PM control strategy.
MG18C402 - VLT
P 3-4* Ramp 1
P 3-5* Ramp 2
Ramp
Current limitations:
•
Currently only supported up to 22 kW
•
Currently limited to non salient type PM motors
•
LC filters not supported together with PM motors
•
Over Voltage Control algorithm is not supported
with PM motors
•
Kinetic backup algorithm is not supported with
PM motors
•
Support reduced AMA of the stator resistance Rs
in the system only
•
No stall detection
•
No ETR function
2.7.3 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 serial bus. If allowed in 0-40 [Hand on] Key on
LCP, 0-44 [Off/Reset] Key on LCP, and 0-42 [Auto on] Key on
LCP, it is possible to start and stop the frequency converter
by LCP using the [Hand On] and [Off/Reset] keys. Alarms
can be reset via the [Off/Reset] key.
®
is a registered Danfoss trademark
100%
0%
To motor
control
100%
-100%
P 4-10
Motor speed
direction