Creating Custom Motor Files
B-5
Installation Manual for Models ODM-005, ODM-005i, ODM-010, ODM-010i, ODM-020 and ODM-020i
Synchronous/Induction
This field identifies whether the motor is a synchronous (permanent magnet) motor or an induction motor.
The motor type informs OMNI LINK which fields are valid for a particular motor, and which fields are
invalid (grayed).
These instructions only cover permanent magnet motors, so the
Synchronous
box must be checked.
Number of Poles
The number of poles specifies the number of electrical cycles in two mechanical revolutions. For example,
a 6-pole motor will have three electrical cycles per mechanical cycle. The firmware can support only 2-
, 4-, 6-, and 8-pole motors.
Occasionally a manufacturer specifies the number of pole pairs in a motor data sheet. Pole pairs should
not be confused with the number of poles. A 6-pole motor has 3 pole pairs.
K
T
(Torque Constant)
The torque constant, also known as the torque sensitivity, specifies the amount of torque that the motor
can produce with a given value of sinusoidal current. The torque constant is measured in units of N-m/
Amp, and its range is 0.0002 to 15.9998 N-m/Amp.
Conversion formulas between N-m/Amp, in-lb/Amp, and oz-in/Amp, are:
The denominator units of the required torque constant are peak Amps, rather than rms Amps. To convert
the torque constant from units of N-m/Amp(rms), use the formula:
Many Thomson Industries motors specify the torque constant in units of N-m/rmsA/phase. In this case,
in addition to conversion from rms Amps to peak Amps, the value needs to be multiplied by three because
it has been defined as “per phase”.
If a motor operates with trap drives, the torque constant is specified as a “square wave” torque constant.
However, OMNIDRIVEs are sinusoidal drives and the torque constant must be specified as a “sine wave”
torque constant or “sinusoidal” torque constant. To convert between sinusoidal torque constants and
square wave torque constants, usually a factor of 5-10% is required. The motor manufacturer should be
able to specify the sinusoidal torque constant, even if it is not shown in the data sheet.
J
M
(Inertia)
The rotor inertia specifies the inertia of the motor, not including the load, and is required in units of Kg-
cm
2
. The inertia can be in the range of 0.0156 to 1023.9844 Kg-cm
2
.
The conversion formulas between Kg-cm
2
, Kg-m
2
, in-lb-s
2
, and oz-in-s
2
are:
K
E
(Back EMF)
The back-EMF is the peak value of the line-to-line sinusoidal EMF generated at 1000 RPM, and is required
in units of Volts/KRPM or Volts/1000 RPM. The back-EMF value can be in the range of 0.0039 to
255.9961 Volts/KRPM.
1
Newton meter
Amp
8.85075
inch pound
Amp
141.612
ounce inch
Amp
⋅
=
⋅
=
⋅
1
Newton meter
Amp
0.707
Newton meter
Amp(rms)
⋅
=
⋅
1 Kg cm
0.0001 Kg m
1
1129.85
in lb s
1
70.6155
oz in s
2
2
2
2
⋅
⋅
=
⋅
⋅
=
⋅ ⋅ ⋅
=
⋅
⋅ ⋅
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