SKS Sweden Bonfiglioli Vectron ACTIVE CUBE ACU 201 Series, Operating Instructions Manual

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212
Operating Instructions ACU
09/08
16.5.6 Modulation Controller
The modulation controller, which is designed as an I regulator, automatically adapts
the output value of the frequency inverter to the machine behavior in the basic speed
area and in the field weakening area. If the modulation exceeds the figure set with
parameter
Reference modulation
750
, the field-forming current component and thus
the flux in the machine are reduced.
In order to make the best possible use of the voltage available, the figure selected
via parameter
Operation mode
753
is put into proportion to the DC link voltage. That
means that with a high mains voltage there is also a high output voltage available,
the drive only reaches the field weakening area later and produces a higher torque.
Operation mode
753 Function
0 - Usq-Control
The modulation is calculated from the ratio of torque-
forming voltage component U
sq
to the DC link voltage.
1 - V-Absolute Value
Control
The modulation is calculated from the abs. voltage value
/ DC link voltage ratio.
The integrating part of the modulation controller is to be set via parameter
Integral
time
752
.
Parameter Settings
No. Description Min. Max. Fact. sett.
750 Reference modulator 3.00 % 105.00 % 102.00 %
752 Integral time 0.0 ms 1000.0 ms 10.0 ms
The percentage setting of the
Reference modulation
750
is basically a function of the
leakage inductivity of the machine. The default value was selected such that in most
cases the remaining deviation of 5% is sufficient as a reserve range for the current
controller. For the optimization of the controller parameters, the drive is accelerated
with a flat ramp into the area of field weakening, so that the modulation controller
intervenes. The limit is set via parameter
Reference modulation
750 . Then, the con-
trol loop can be excited with a unit step function by modifying the reference modula-
tion (change-over between 95% and 50%). By means of an oscillographed mea-
surement of the flux-forming current component on the analog output of the fre-
quency inverter, the controlling process of the modulation controller can be assessed.
The course of the signal of the flux-forming current I
sd
should reach the stationary
value after overshooting without oscillation. An oscillating of the course of the current
can be damped by increasing the integral time. The parameter
Integral time
752
should roughly correspond to the actual value
Act. rotor time constant
227.
Operating Instructions ACU 09/08 212