Omron MX2 - Torque Control Algorithms; Constant and Variable (Reduced) Torque; Sensorless Vector Control; Free V;F Control

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"A" Group: Standard Functions Section 3-5
3-5-4 Torque Control Algorithms
The inverter generates the motor out-
put according to the V/f algorithm
selected. Parameter
A044 selects the
inverter algorithm for generating the
frequency output, as shown in the
diagram to the right (
A244 for 2nd
motor). The factory default is
00 (con-
stant torque).
Review the following description to
help you choose the best torque con-
trol algorithm for your application.
The built-in V/f curves are oriented toward developing constant torque or vari-
able torque characteristics (see graphs below). You can select either constant
torque or reduced torque V/f control.
Constant and Variable (Reduced)
Torque - The graph at right shows
the constant torque characteristic
from 0 Hz to the base frequency
A003.
The voltage remains constant for out-
put frequencies higher than the base
frequency.
The graph above (right) shows the
variable (reduced) torque curve,
which has a constant torque charac-
teristic from 0 Hz to 10% of the base
frequency. This helps to achieve
higher torque at low speed with
reduced torque curve at higher
speeds.
Sensorless Vector Control - You
can achieve high torque performance
(200% torque at 0.5 Hz of output fre-
quency) without motor speed feedback (encoder feedback), which is so-called
sensorless vector control (SLV control).
Free V/F Control - The free V/F setting function allows you to set an arbitrary
V/F characteristics by specifying the voltages and frequencies (
b100~b113) for
the seven points on the V/F characteristic curve.
The free V/F frequencies 1 to 7 set by this function must always be in the col-
lating sequence of "1<2<3<4<5<6<7".
Since all the free V/F frequencies are set to 0 Hz as default (factory setting),
specify their arbitrary values (being set with free-setting V/F frequency 7). The
inverter does not operate the free V/F characteristics with the factory setting.
Enabling the free V/F characteristics setting function disables the torque boost
selection (
A041/A241), base frequency setting (A003/A203), and maximum fre-
Inverter Torque Control Algorithms
00
A044
Output
01
02
03
V/F control
constant torque (V/F-VC)
V/F control,
variable (1.7) torque
V/F control,
Free V/f
Sensorless vector
Control (SLV)
Hz
100%
0
V
A044
=
00
Constant torque
A044
=
01
Hz
100%
0
V Variable torque
Max.
freq.
Base
freq.
Max.
freq.
Base
freq.
10% Base
freq.