Selection criteria
SELECTING CRITERIA
Asynchronous spindle motor and servo drive selection
5.
215
DDS
HARDWARE
Ref.1310
Limited acceleration and choke. Choke = (acceleration / t).
The capability demanded from the motor is determined by the following
formulas:
We will now give several examples of calculations using a mechanical
specifications and for a standard motor. The results could vary from real
ones through mechanical losses, fluctuations in mains voltage, or inaccu-
racies of mechanical data.
T. H5/3 Different accelerations depending on speed.
Method Different accelerations depending on speed
Control Linear acceleration avoiding abrupt variations in
transmitted torque.
Comment
Emulation of the square sine function for speed by
using ramps.
F. H5/10
Acceleration and choke limit.
T. H5/4 Acceleration and choke limit.
Method Acceleration and choke limit.
Control
Progressive linear acceleration, avoiding abrupt vari-
ations of transmitted torque.
Comment
Approach square sine function (bell shape) for the
speed.
Capacity required by the motor
in the constant torque area:
(0 < N
M
< N
B
)
Capacity required by the motor
in the constant torque and con-
stant power area:
(0 < N
M
< N
max
)
J
M
Inertia of the load in kg·m² as viewed from the motor shaft
P
N
Rated power at base speed kW
Nmax
Maximum motor speed in rev/min.
N
B
Motor base speed in rev/min.
N
M
Motor speed reached after a time period t in rpm
t
Acceleration time until N
M
(in seconds) is reached
Example.
Data:
Acceleration time:
Between 0 and 1500 rpm in 0.5 s. (1)
Between 0 and 6000 rpm in 2.5 s. (2)
Motor inertia:
J
motor
= 0.13 kg·m²
Motor base speed:
N
b
= 1500 rev/min
P
N
2
60
------
2
J
M
N
M
2
1000 t
--------------------kW=
P
N
2
60
------
2
J
M
N
M
2
N
B
2
+
2000 t
---------------------------------------kW=
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