Torque Control Algorithms - Hitachi WJ200 Series Instruction Manual

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Torque Control Algorithms

The inverter generates the motor output
according
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 (constant torque).
Review the following description to help you
choose the best torque control algorithm for your
application.
The built-in V/f curves are oriented toward developing constant torque or
variable 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 0Hz to the base frequency
A003. The voltage remains constant for output
frequencies higher than the base frequency.
The graph above (right) shows the variable (reduced) torque curve, which has a
constant torque characteristic from 0Hz 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
0.5Hz of output frequency) 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 collating
sequence of "1<2<3<4<5<6<7".
Since all the free V/F frequencies are set to 0Hz 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.
to the V/f algorithm
Inverter Torque Control Algorithms
selected.
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)
V A044
100%
0
V A044
100%
0
10% Base
freq.
00
A044
01
02
03
Output
00 Constant torque
=
Hz
Max.
Base
freq. freq.
01 Variable torque
=
Hz
Base Max.
freq. freq.