MOOG
ID
No.: CB40859-001 Date: 02/2018
MSD Servo Drive- Device Help
139
7 Control
7.6.2Variant2:Modifiedcharacteristic
Combination of "pre-control with modified 1/n characteristic (isd=f(n)) + voltage
controller. This characteristic describes the magnetizing current as a percentage of
the nominal value of P340[0] - CON_FM_Imag dependent on the speed. The
choice between the modified 1/n characteristic and the static characteristic is based
on P341[0] - CON_FM_ImagSLim.
The speed is specified relative to the rated speed in P458[0] - MOT_SNom, the d-
current relative to the magnetizing current in P340[0]. A constant magnetizing
current P340[0] is injected up to the field-weakening speed. The d current will be
set as a function of speed based on the configurable characteristic curve. The
characteristic curve is configured with P342 CON_FM_SpeedTab and P343 -
CON_FM_ImagTab; when using an asynchronous motor, only values 0–7 from
ImagTab will be relevant; values 8–15 are intended for synchronous motor field
weakening
7.6.3Voltagecontroller
The superimposed voltage controller will be a PI controller with gain P345[0]-
CON_FM_VConKp and reset time P346[09]-CON_FM_VConTn. In addition, the
measured DC link voltage can be smoothed with a P344[0]-CON_FM_VConTF
PT1 filter. After a motor identification the voltage controller is always active, as the
rule parameters are preset. With P345[0] - CON_FNVConKp = 0 the voltage
controller is deactivated. The voltage setpoint that needs to be achieved is specified
using P347[0]-CON_FM_VRef.
Example
Index
P 348
rated
speed;
P 340
I
mag
eff
P 342 (0-7) field
weakening speed
[%]
P 343 (0-7) Magnetising cur-
rent in field weakening mode
[%]
(0)
I
rated
=
1800 rpm
I
mag eff
=
100%
100 100
(1) 110 100
(2) 120 100
(3) 130 100
(4) 140 90
(5) 150 70
(6) 160 55
(7) 170 0
Table 7.21: Example of modified characteristic curve
ID Index Name Unit Description
430 0
340 0 A
341
341 0 %
341 1
CON_FM_VModel
CON_FM_Imag
CON_FM_ImagSettings
ImagSLim
Imag0 %
Inom
Weightingofvoltagepathinfieldmodel
Magnetizingcurrent(RMS)
Settingsofmagnetizingbehaviour
Speedwherefield-weakeningstarts
Magnetizingcurrentduringstart-up
342 Speedvaluesformagnetizingcurrentscaling
342 0 %
342 1 %
342 2 %
342 3 %
342 4
CON_FM_SpeedTab
CON_FM_SpeedTab
CON_FM_SpeedTab
CON_FM_SpeedTab
CON_FM_SpeedTab
CON_FM_SpeedTab %
Table 7.22: “Field-weakening” parameters