Siemens SIMOVERT MASTERDRIVES Manual page 870

06.2005
Siemens AG 6SE7087-6QX70 (Version AE)
SIMOVERT MASTERDRIVES
If induction servomotors are used, the permissible motor torque in the
field-weakening range is reduced by the stalling limit. Here, a distance
of approximately 30 % should be kept to.
M
Mot
M
max perm.
Points of load cycle
S1 curve
M
n
Fig. 11-8 Limit curves for 1PA6 motors (induction servomotors)
In order to keep a check on the dynamic limits, the relevant points of
the torque curve must be calculated. In general, the motor torque at
maximum speed during the acceleration phase is decisive. The motor
torque and motor speed are calculated as follows when load torque,
speed under load and angular acceleration/deceleration on the gear-
output side are known:
Transmission ratio i
Motor
J
Mot
= ⋅ ⋅ α
M J i
Mot Mot b v load ,
= ⋅
n i n
Mot load
J
Mot
Motor inertia
*
J
G
Gear moment of inertia referred to motor speed
η
Gear efficiency
G
Compendium Motion Control
30% distance
n
η
J
,
G
G
*
+ ⋅ ⋅ α +
J i M
G b v load , load
Engineering Information
Stalling limit
n
n
Mot
n
load
M
load
α
b,v load
1
⋅
Sign M ( )
⋅ η
i
load
G
11-13