MOOG
ID
No.:
CB40859-001
Date:
02/2018
MSD Servo Drive - Device Help
139
7 Control
7.6.2 Variant 2: Modified characteristic
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 P 340[0] - CON_FM_Imag dependent on the speed. The
choice between the modified 1/n characteristic and the static characteristic is based
on P 341[0] - CON_FM_ImagSLim.
The speed is specified relative to the rated speed in P 458[0] - MOT_SNom, the d-
current relative to the magnetizing current in P 340[0]. A constant magnetizing
current P 340[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 P 342 CON_FM_SpeedTab and P 343 -
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
7.6.3 Voltage controller
The superimposed voltage controller will be a PI controller with gain P 345[0] -
CON_FM_VConKp and reset time P 346[09] - CON_FM_VConTn. In addition, the
measured DC link voltage can be smoothed with a P 344[0] - CON_FM_VConTF
PT1 filter. After a motor identification the voltage controller is always active, as the
rule parameters are preset. With P 345[0] - CON_FNVConKp = 0 the voltage
controller is deactivated. The voltage setpoint that needs to be achieved is specified
using P 347[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
Weighting of voltage path in field model
Magnetizing current (RMS)
Settings of magnetizing behaviour
Speed where field-weakening starts
Magnetizing current during start-up
342
Speed values for magnetizing current scaling
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
