Siemens Simovert Masterdrives Compendium page 278

09.2008
Siemens AG 6SE7087-6QX70 (Version AK)
SIMOVERT MASTERDRIVES
3. Set the characteristic to meet requirement "Maximum torque in field
weakening range remains constant":
The output voltage (r003) at the field weakening activation speed
under no load conditions must be measured. The output voltage at
the end point of the desired field weakening range must then be
calculated according to the following formula from the maximum
converter output voltage (depends on converter supply voltage) and
the calculated output voltage at the field weakening activation
speed:
=
U U
Conv Out nEnd Conv
where
=
U 350 V (
Conv max
=
U Output
Conv Out nEnd
=
U Output
Conv Out nAct
n
=
End
k Field weakening
f
n
Act
w eakening
The formula is based on the simplified principle that the voltage drop
across the winding resistance of the motor is negligible in the field
weakening range. This applies to series 1FT6 and 1FK7 servo
motors.
The output voltage calculated by this formula must then be set at the
end speed of the field weakening range at no load via the short-
circuit current. The current setting must be increased in relation to
the automatically calculated value, as the automatic arameterization
run defines the short-circuit current for operation at constant
maximum output.
100
90
80
70
60
50
40
30
20
10
0
0 500 1000
e.g. 1FT6086-8AF71, 27.5 Nm at 2900 rev/min to 4500 rev/min,
U = 296 V, U
(no load 2900)
Compendium Motion Control
( )
2 ⋅ − 2 +
1 k U
max f Conv
=
when UDCL 540 V )
v oltage at end of field
voltage at field weakening
range : Ratio
speed a nd field weakening
1FT6086 - 8AF71
1500 2000 2500
Speed [min-1]
= 174 V I
(no load 4500)
Functions
2 ⋅ 2
k
Out nAct f
weakening range
activation speed
between final field
activation speed
Field
weakening
activation point
3000 3500 4000
(P105) = 60 A
k
4500
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