Santerno Sinus Penta - Page 44

SINUS PENTA
PROGRAMMING GUIDE
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attained. Decrease P128 and P129 by approx. 30%, then decrease the high values set for integral
time in P125 and P126 (keep both values equal) until an acceptable setpoint response is obtained.
Check to see if the motor runs smoothly at constant speed.
10) Possible
failures:
If no failure occurred, go to step 11. Otherwise, check the drive connections paying particular
attention to supply voltages, DC link and input reference. Also check if alarm messages are
displayed. In the MEASURES MENU, check the reference speed (M000
), the reference speed
processed by the ramps (M002), the supply voltage of the control section (M030), the DC-link
voltage (M029), the condition of the control terminals (M033
). Check to see if these readouts
match with the measured values.
11) Additional
parameter
modifications:
If the motor control is underperfoming, make sure that the following measurements are consistent
with the expected motor operation:
- estimated speed M004 in respect to speed ramp M002,
- output frequency M006,
- generated torque M012 and torque demand M011,
- output current M026,
- output voltage M027.
Proceed as follows:
Issue
What to do
Generation of weak torque
or inaccurate torque
delivery
Increase the flux boost at low frequency P175h1 and adjust the
frequency range for the boost to occur via parameters P175i1
and P175j1.
The magnetization current at low frequency with
active current boost equals the no-load current value in C021
increased by the value in P175h1 (for example, if C021=27%
and P175h1=30%,
the magnetization current is
27%x1.3=35.1%). Up to the frequency value in P175i1, the
magnetization current is C021 x (1+P175h1);
at a frequency
higher than P175j1, the magnetization current is C021; at
intermediate frequency values, the magnetization current follows
a linear pattern. Too high magnetization current values may lead
to saturation of the motor flux, lower efficiency due to greater no-
load current, inaccurate torque adjustment or controller
instability. It is suggested that P175j1 be applied at its maximum
value up to 50% of the rated frequency. Also, set P175i1 in such
a way so
as to obtain a rather smooth pattern (for example,
P175i1 set to half the value in P175j1). In case P175i1 and
P175j1
are not correctly adjusted, torque adjustment may be
uneven or current variations may occur.
Generation of weak torque
at high speed
If the motor is not capable of delivering high torque at high speed
(close to rated torque or field weakening torque) o
r requires
excessive current in respect to the expected current, it is
possible to adjust rotor time constant C025.
Generation of weak torque
at low speed or in
regenerative mode
Change current distortion compensation parameters in VTC
control P175a, P175b, P175c.
Change current distortion
compensation P175b first, then change positive and negative
current split P175c.
For high values in P175b, also increase the linear pattern
threshold in P175a. If parameter P175b is set too high or P175a
is set too low, rotor oscillations may occur, or it may happen that
the rotor is not kept standstill even in no-load conditions. If this is
the case, set lower values for the parameters above.
Low output voltage or weak
torque in field weakening
mode
Disable static field weakening by setting C030 = Disable and
enable automatic field weakening by setting C030a >0.
In
that way, the field weakening amplitude is automatically
adjusted to ensure adjusting the required speed at the maximum
allowable voltage fitting the rated motor voltage and the available
DC voltage.
When parameter P003 = Standby Only (condition required for changing Cxxx
parameters), you
can change Cxxx parameters only when the drive is DISABLED or STOPPED, whereas if P003 =
Standby + Fluxing, you can change Cxxx parameters when the motor is stopped but the drive is
enabled.
Before changing any parameters, remember that the correct code for parameter P000 must be