Zero-Speed Range (Zero-Hz Range) Sensorless Vector Control - Omron RX2 Series User Manual

Phenomenon
Revolution in the
opposite direction to
the command direction
occurs for an instant.
Precautions for Correct Use
• Set the carrier speed setting, 1st-motor [bb101] at a value of 2.0 kHz or higher. A set fre-
quency of 1.9 kHz or lower may cause hunting.
• When the revolution of the motor is hindered by such causes as the braking or the motor lock
caused by foreign objects, such hindrance may cause over current or the like. When no such
adjustment as ones mentioned above improves the state, checking the portion around the
motor may sometimes improves it.
• If an application of load results in a great amount of change in the inverter's output frequency
monitor [dA-01], a function to automatically change the frequencies for the overload limiting
function, the momentary-stop non-stop function, the over voltage suppression function may
work depending upon the settings of the functions.
7-2-9

Zero-speed Range (Zero-Hz Range) Sensorless Vector Control

This application is used on such as lifts and cranes, that require a high torque from the start.
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.
A motor constant and the load inertia must be set with auto-tuning, etc.
As in the case of the sensorless vector control, acquire the motor constant by means of auto-tuning or
the like.
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 for Async.M, 1st-motor
[HA115] may improve the state of the motor.
The zero-speed range sensorless vector control cannot be used at the light load mode or the extra light
load. When you select a load type selection (Ub-03), use the mode as 02: ND (Standard).
Precautions for Correct Use
• 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 that a length of a wire is over 20 m, the motor's characteristic may be below what
are expected.
• As the capacity becomes farther away from the maximum applicable motor capacity, suffi-
cient operation characteristics becomes more difficult to get.
High-function General-purpose Inverter RX2 Series User's Manual
Estimated cause(s)
A command demand-
ing the revolution in
the opposite direction
Enable the reversal prevention selection [HC114].
is dispatched over the
control system for an
instant.
7 Advanced Settings
Exemplar measures to be taken
7
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