Hitachi SJ Series, User Manual

Page: 231 / 786

12-9-14
Chapter 12 Inverter Function
12.9.10 Use zero-speed range (zero-Hz
range) sensorless vector control
• To use in applications, such as cranes, that require
a high torque at the start.
• To accurately control the frequency.
• Automatically adjust the frequency and the output
voltage so as to achieve responsively a higher
torque even at slow speeds.
• In the zero-speed range sensorless vector control,
the sensorless vector control is supplemented with
an output that can achieve an intended torque from
at extremely low speeds such as those in the
zero-speed range.
• Even in the case of Hitachi's standard motors, a
large load inertia and/or a long wiring may require
the auto-tuning.
• Use of other motors than Hitachi's standard motors
requires the setting-up of the motor constant and
the load inertia by, for example conducting the
auto-tuning.
• As in the case of the sensorless vector control,
acquire the motor constant by means of
auto-tuning or the like.
Parameter
• In the zero-speed range sensorless vector control,
as in the case of the sensorless vector control, set
appropriately the motor capacity, the number of
motor poles, the base frequency, the rated voltage,
and the rated current in order to conduct motor
control.
• When the motor performs below its potential
characteristics, conduct the auto-tuning and make
adjustment by referring to the next section.
• In the case of a long wiring (approximately longer
than 20 m) and in the case of controlling motors
other than out company's, the performance may be
below what are expected from the characteristics.
• As the capacity becomes farther away from the
maximum applicable motor capacity, sufficient
operation characteristics becomes more difficult to
get.
• In the zero-speed range sensorless vector control,
as in the case of the sensorless vector control,
adjustment of the response is possible. In addition
to the adjustment of the response, it is possible to
set the torque boost for the current at the start.
• When a motor is hunting and vibrating, an
adjustment of the speed response [HA115] may
improve the state of the motor.
Item Parameter Data Description
Control mode [AA121] 09
To use the zero-speed range
sensorless vector control (IM) function.
Speed response [HA115] 0~1000(%)
To adjust the responsiveness of the
control.
A larger value enhances the
responsiveness.
Zero-speed range limiter [HC110] 0~100(%)
To limit the current at the start so as not
to allow the rising of the current to rise
too high.
Amount of boost at the start
(zero-speed range sensorless
vector)
[HC112] 0~50(%)
To adjust the current command at the
start when the starting torque is not
sufficient.
Time constant for torque current
command filter
[HC120] 0~100(ms)
To adjust the filter for the torque
current.
Speed feed forward
compensation adjustment gain
[HC121] 0~1000(%)
To adjust the feed forward control of the
speed controller.
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