10.3 Equations for Selections
10-12
Before proceeding this calculation, obtain the motor shaft moment of inertia J
1
, the load shaft moment of inertia
converted to motor shaft J
2
, maximum load torque converted to motor shaft τ
L
, and the reduction-gear efficiency η
G
.
Apply the maximum motor output torque τ
M
according to an actual speed thread ΔN as follows.
[τ
M
in N ≤ N
0
] Constant output torque range
(Equation 10.3-18)
[τ
M
in N
0
≤N ≤ N
1
] Constant output power range
(The motor output torque is inversely proportional to the motor speed)
(Equation 10.3-19)
If the result obtained by the above calculation does not satisfy the target value, select an inverter with one rank
higher capacity.
[ 5 ] Calculating non-linear deceleration time
Use the following expression to obtain the non-linear deceleration time as well as for the acceleration time.
)s(
60
N2
JJ
t
GLM
G
21
DEC
Dπ
ηττ
η
+
=D
•
•
•
•
−
(Equation 10.3-20)
In this expression, both τ
M
, and ΔN are generally negative values so that the load torque τ
L
serves to assist the
deceleration operation. For a lift load, however, the load torque τ
L
is a negative value in some modes. In this case,
the τ
M
, and τ
L
will take polarity opposite to each other and the τ
L
will actuate to prevent the deceleration operation of
the lift.
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