DRIVE SETUP
68
Per-Unit Inertia
Function 41
Sets all regulator gains to adjust for elevator
system inertia. The numeric value of Per Unit
Inertia is a ratio of equivalent rotating inertia
Vs rated motor strength. Units are in
seconds. If System Inertia is set too low,
velocity overshoot will occur. If set too high,
there may be hesitation or undershoot when
approaching a new target speed.
Stiffness
Function 42
Sets the gain of internal PI error amplification
and inner loop regulator gain. Affects the
responsiveness of the drive to ignore or react
to load disturbances. Range 0.5 to 9. No
calibrated units. Low numeric values will yield
smooth performance while following reference
changes. High numeric values will yield better
response to speed errors and load
disturbances, but can cause amplification of
elevator rope resonance.
Gain Switch Speed
Function 105
Sets the speed where regulator gain will
switch bandwidths. Below this speed the
setting of #40 will be used. Above this speed,
the effective setting of Bandwidth #39 will be
used. Units are in Per Unit of rated speed
(where 1.00 represents 100% of rated speed).
The default setting of 1.1pu means that
regulator bandwidth will never switch, and
therefore always be controlled by #40.
Gain Reduce
Function 108
The Gain Reduce multiplier function has been
replaced by two separate settings, #39 & #40.
Tach Rate Gain
Function 107
Sets the amount of derivative speed feedback
from the encoder. Units are in %, with range
from 0 to 30%. This can help stabilize
velocity-tracking oscillation caused by rope
stretch in tall hoist-ways. Not an effective
countermeasure against ordinary rope
resonance.
Notch Filter
Function 190 & 191
An adjustable frequency notch filter is
provided to help suppress regulator
responses to a specific frequency. This is an
effective countermeasure to avoid
amplification of typical 9 – 14 Hz rope
resonance. See Table 8
Tuning E-REG
The basic concept and purpose of E-Reg is to
have a relatively low closed encoder loop
bandwidth to prevent amplification of natural
rope oscillations, but to feed changes in the
velocity reference directly forward to control
motor torque with a relatively high gain. This
then forces the inertia of the elevator to follow
the reference speed, while the relatively low
gain PI error regulator is required to only
make minor corrections. This is ideal for
elevators and lifts, as they tend to be relatively
high inertia loads with a steady load torque
offset while running. The steady state load
torque is a function of elevator cab, payload,
and counterweight gravity balance and will be
different for each elevator run as it is a
function of payload and direction. Most
elevators will have minimal operating friction.
Verify that settings for basic parameters are
correct and that the armature current/torque
regulator and motor field regulator are
properly tuned. The critical adjustments
include:
Motor armature – I-lim #1, Self-Tune #2,
Rated-Amps #3, R #4, L #6, VDC #7, Ix #8, &
VAC #9.
Motor Field – WkAdc #49, RtdAdc #50, L/R
#51, VDC #52, Istndby #53, Response #54,
SourceVAC #55.
Speed Loop – EncoderPPR #10, RPM #11,
Ratio #16, Rtd Spd #17
Setting Per-Unit Inertia Function 41
Be sure to have completed adjustment of the
motor field current regulator BEFORE making
final adjustments of system inertia. Start with
default values for Response Bandwidth #39
&40, Per Unit Inertia #41 and Stiffness #42.
Use a speed profile with a minimal amount of
S-Curve smoothing. Select two elevator
landings far enough apart so that the elevator
can attain maximum speed between stops.
[But not the end landings during initial tuning.]
It is a good idea to begin at a restricted low
speed like inspection speed for initial
verification. Run the elevator up and down
repeatedly between the same two landings
while monitoring car speed via function #600
on the DSD 412 local display. The objective is
to have the car speed accelerate right up to
the desired speed, so look for speed
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