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11.SELECTION
[r/min]
T
= T
+ T
+ T
1
Ma
a
L ..........................................................................................................................................................................
T
= T
2
L ....................................................................................................................................................................................................
T
= T
= - T
+ T
3
Md
d
L
Note: In the regenerative mode, the value found by Equation 11-13 is negative.
(
4) Continuous effective load torque
If the torque required for the servo motor changes with time, the continuous effective load torque
should be lower than the rated torque of the servo motor. There may be a servo motor torque
delay at the start of acceleration or deceleration due to a delay in the control system. To simplify
the calculation, however, it is assumed that constant acceleration and deceleration torques are
applied during Tpsa and Tpsd. The following equation is used to calculate the continuous effective
load torque in the following operation pattern:
2
T
• T
+ T
Ma
psa
T
=
rms
Note: T
indicates the torque applied during a servo motor stop. A large torque may be applied
LH
especially during a stop in vertical motion applications, and this must be fully taken into
consideration. During vertical drive, the unbalanced torque T
Command
Nofo
Servo motor
speed
f
0
[pps]
Tpsa
T
1
T
Ta
Ma
T
2
T
L
0
Td
T
Md
.................................................................................................................... (11-13)
N
0
[r/min]
Ta
T
Ma
T
L
0
Td
Tpsa
tc
Tf (1 cycle)
2
2
• t
+ T
• T
+ T
L
c
Md
psd
t
f
11– 7
Time
Tpsd
Time
Time
T
LH
Time
T
Md
Tpsd
Tr
• t
LH
R
......................................................... (11-14)
will become T
U
(11-11)
(11-12)
.
LH
11
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