Omron RX2 Series User Manual page 334

7 Advanced Settings
Phenomenon
Hunting occurs at
higher speeds (at the
lowest frequency
(switch) or higher).
A long initial position
estimation time is
required.
A movement in the
opposite direction
occurs while the initial
position estimation is
being used.
While the initial posi-
tion estimation is being
used, over current
errors may occur.
Frequency-synchro-
nized re-start may
cause errors.
Precautions for Correct Use
• 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, loss of synchronization,
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.
IVMS Start Sensorless Vector Control (SM/PMM)
In this control mode, operations of magnetic-pole position estimation, IVMS start control, and sensor-
less vector control are started in this order.
In this control mode, only the parameters set by the first set-up are enabled. Terminal [SET] cannot be
used.
In the magnetic-pole position estimation, it is possible to select whether the motor is started after the
motor's magnetic-pole positions are estimated by use of the initial-position estimation function or the
magnetic-pole positions are synchronized by use of the DC braking function.
In the case of starting after the magnetic-pole position estimation, estimation operation is conducted at
the start by setting the Starting Method for Sync.M, 1st-motor [Hd132] at 01.
In the case of the Starting Method for Sync.M, 1st-motor [Hd132] being set at 00, the magnetic poles
are positioned to the output phases at the start. As a large offset between the magnetic poles and the
output phases may fail the starting, use the starting-time DB to synchronize the magnetic-pole positions
and the output phases before the starting.
IVMS start mode is a start mode where larger torque is provided than in the synchronous starting mode.
When the synchronous starting mode provides an insufficient torque, use of the IVMS start mode may
improve the performance.
Use of the IVMS start mode requires an SM(PMM) constant that is set by the sensorless vector control
and an adjustment dedicated for IVMS start mode.
Before the motor drive, conduct an IVMS auto-tuning and a test run with the load removed.
7 - 26
Estimated cause(s)
Unsynchronized speed Make an adjustment by incrementing/decrementing the speed
response. response [HA115] by 5% each time.
Distorted wave form of Make an adjustment by incrementing the no-load current
the radio wave. [Hd131] by 5% each time.
Lower the values [Hd133] to [Hd135] by the same ratio.
Set value for the esti-
Note Too low a value may result in an operation in the oppo-
mation is too large.
site direction.
The estimation is Raise the values [Hd133] to [Hd135] by the same ratio, or
improperly conducted. raise the voltage gain [Hd136] by 5% each time.
Voltage gain is too
Decrement the voltage gain [Hd136] by 5% each time.
high.
Too high revolution Make an adjustment by incrementing the speed response
speeds and too large [HA115] by 5% each time. Waiting a longer time for the re-start
offset of the phases. may improve the situation.
High-function General-purpose Inverter RX2 Series User's Manual
Exemplar measures to be taken