converter will estimate the rotor position and start normal
operation from there.
=
[1] Parking
:
If the speed estimate comes out lower than the setting in
1-59 Flystart Test Pulses Frequency
then the Parking function
will be engaged (see
and
). Otherwise the frequency converter will catch the
motor at that speed and resume normal operation. Refer
to description of
for recommended
settings.
Current limitations of the Flystart Principle used for PM
motors:
•
The speed range is up to 100% Nominal Speed or
the field weakening speed (which ever is lowest).
•
PMSM with high back emf (>300 VLL(rms)) and
high winding inductance(>10 mH) needed more
time for reducing short circuit current to zero and
may be susceptible to error in estimation.
•
Current testing limited to a speed range up to
300 Hz. For certain units the limit is 250 Hz; all
200-240 V units up to and including 2.2 kW and
all 380-480 V units up to and including 4 kW.
•
Current testing limited to a machine power size
up to 22 kW.
•
Pred for salient pole machine (IPMSM) but not yet
verified on those types of machine.
•
For high inertia applications (i.e. where the load
inertia is more than 30 times larger than the
motor inertia) a brake resistor is recomended to
avoid over-voltage trip during high speed
engagement of the fly-start function.
1-77 Compressor Start Max Speed [RPM]
Range:
Function:
Size
related
*
[ 0 -
par.
4-13
RPM]
The parameter enables “High Starting
Torque”. This is a function, where the Current
Limit and Torque Limit are ignored during
start of the motor. The time, from the start
signal is given until the speed exceeds the
speed set in this parameter, becomes a
“start-zone” where the current limit and
motoric torque limit is set to what is
maximum possible for the frequency
converter/motor combination. This parameter
is normally set to the same value as
4-11 Motor Speed Low Limit [RPM]
. When set
to zero the function is inactive.
In this “starting-zone”
is active instead of
3-40 Ramp 1 Type
to
ensure extra acceleration during the start and
to minimize the time where the motor is
operated under the minimum speed for the
application. The time without protection
1-77 Compressor Start Max Speed [RPM]
Range:
Function:
from the Current Limit and Torque Limit
must not exceed the value set in
1-79 Compressor Start Max Time to Trip
or the
frequency converter will trip with an alarm
[A18] Start Failed.
When this function is activated to get a fast
start then also
1-86 Compressor Min. Speed for
Trip [RPM]
is activated to protect the
application from running below minimum
motor speed e.g. when in current limit.
This function allows high starting torque and
use of a fast starting ramp. To ensure the
build-up of a high torque during the start,
various tricks can be done through clever use
of start delay/start speed/start current.
NOTE
1-77 Compressor Start Max Speed [RPM]
will not have effect
when
= [1] PM, non salient SPM.
1-78 Compressor Start Max Speed [Hz]
Range:
Function:
Size
related
*
[ 0 -
par.
4-14
Hz]
The parameter enables “High Starting
Torque”. This is a function, where the Current
Limit and Torque Limit are ignored during
start of the motor. The time, from the start
signal is given until the speed exceeds the
speed set in this parameter, becomes a “start-
zone” where the current limit and motoric
torque limit is set to what is maximum
possible for the frequency converter/motor
combination. This parameter is normally set
to the same value as
. When set to zero the function is
inactive.
In this “starting-zone”
is active instead of
to ensure extra acceleration during
the start and to minimize the time where the
motor is operated under the minimum speed
for the application. The time without
protection from the Current Limit and Torque
Limit must not exceed the value set in
1-79 Compressor Start Max Time to Trip
or the
frequency converter will trip with an alarm
[A18] Start Failed.
When this function is activated to get a fast
start then also
1-86 Compressor Min. Speed for
Trip [RPM]
is activated to protect the
application from running below minimum
motor speed e.g. when in current limit.
This function allows high starting torque and
use of a fast starting ramp. To ensure the
build-up of a high torque during the start,
Parameter Description
VLT
®
Refrigeration Drive Programming Guide
MG16H102 - VLT
®
is a registered Danfoss trademark
45
3
3
