Siemens Simovert Masterdrives Compendium page 914

Engineering Information
11-14
With the motor torque of lifting drives, a difference is made between
upwards and downwards:
= ⋅ ⋅ α
M J i
Mot up Mot b v load ,
= ⋅ ⋅ α
M J i
Mot down Mot b v load
α
and M have to be applied with the correct signs (see also
b v load , load
the examples under 11.3). If further moments of inertia are present on
the motor side (e.g. coupling), these must also be taken into account.
In addition to the torque determined by the load and by the gears, the
torque required for accelerating or decelerating the rotor's moment of
inertia during dynamic processes is added to the motor torque.
= ⋅ ⋅ α
M J i
b v Mot , Mot
Now a motor has to be selected which fullfils the condition for the
maximum motor torque in the required speed range. The proportion of
the acceleration torque for the motor rotor in relation to the maximum
motor torque depends on the motor's moment of inertia and the angular
acceleration but also on the moment of inertia of the load, the gear
transmission ratio and the static load torque.
A second point to be checked is whether the thermal limits are adhered
to.
*
+ ⋅ ⋅ α +
J i M
G b v load ,
*
+ ⋅ ⋅ α +
J i
, G b v load ,
b v load ,
6SE7087-6QX70 (Version AE)
Compendium Motion Control
06.2005
1
⋅
load up
Sign M ( )
⋅ η
load up
i
G
Sign M (
η
load down
⋅ G
M
load down
i
Siemens AG
SIMOVERT MASTERDRIVES
)