Parameter conversions – Rockwell Automation 1398-DDM-xxx USE MNL/ULTRA 200 DIG.SERVO.DR User Manual
Page 279
Publication 1398-5.0 – October 1998
Creating Custom Motor Files
D-15
Parameter Conversions
The 1:50 gearing makes this motor an unusual case. The motor file
must be generated as if the motor and gear are two separate devices.
The inertia, torque, speed, etc., must be computed based on the motor
side of the gearing, rather than the load side.
The maximum speed of the motor, before gearing, is computed as:
The torque constant of the motor, before gearing, is computed as:
The back-EMF constant of the motor, before gearing, is computed as:
Note that the back-EMF was specified as a per phase value, and is
doubled to obtain a line-to-line value.
The motor inertia, before gearing, is computed as:
The resistance and inductances are also specified as per phase values,
and are computed as:
The thermal constant is specified in minutes, and is computed as:
Intro
( )
V
rev
min
50
4000
rev
min
MAX
=
⋅
=
80
Intro
K
270
in lb
Amp
1
8.85075
N m
in lb
1
50
0.61
N m
Amp
T
=
⋅
⋅
⋅
⋅
⋅
=
⋅
Intro
( )
K
1.1
Volts
RPM
1000
1
RPM
KRPM
2
1
50
44
Volts
KRPM
E
=
⋅
⋅
⋅
=
Intro
(
)
J
5 in lb s
1129.85
Kg cm
in lb s
1
50
2.26 Kg cm
M
2
2
2
2
2
=
⋅ ⋅
⋅
⋅
⋅ ⋅
⋅
=
⋅
Intro
( )
L
5.0
mH
Phase
2
10.0 mH
L -L
=
⋅
=
( )
R
3.7
Ohms
Phase
2
7.4 Ohms
L -L
=
⋅
=
Intro
(
)
thermal time constant
30 min
60
sec
min
1800 sec
=
⋅
=