Mitsubishi Electric FR-A820-00046 Instruction Manual page 338

Torque control under Real sensorless vector control and vector control
NOTES During Real sensorless vector control, offline auto tuning must be performed properly before
starting operations.
The carrier frequency is limited during Real sensorless vector control. (Refer to page 5-227.)
Torque control cannot be performed for low-speed regenerative driving and low-speed light load.
Vector control must be selected.
Performing pre-excitation (LX signal and X13 signal) under torque control may start the motor
running at a low speed even when the start signal (STF or STR) is not input. The motor may run
also at a low speed when the speed limit value = 0 with a start command input. It must be con-
firmed that the motor running will not cause any safety problem before performing pre-excita-
tion.
Switching between the forward rotation command (STF) and reverse rotation command (STR)
must not be performed during operations under torque control. Otherwise, an overcurrent trip
(E.OC[]) or opposite rotation deceleration fault (E.11) will occur.
When performing continuous operations under Real sensorless vector control in FR-A820-
00250(3.7K) or lower or FR-A840-00126(3.7K) or lower, the speed fluctuation increases at 20 Hz or
less, and in the low-speed range of less than 1 Hz, there may be torque shortage. In such case,
make a stop once and start again to improve the operating condition.
If starting may occur while the motor is coasting under Real sensorless vector control, the fre-
quency search must be set for the automatic restart after instantaneous power failure function
(Pr. 57 ≠ "9999", Pr. 162 = "10").
When Real sensorless vector control is applied, not enough torque may be provided in the ultra
low-speed range of about 2 Hz or lower.
Generally, the speed control range is as follows.
For power driving:
1:200 (2, 4 or 6 poles) (available at 0.3 Hz or higher when the rating is 60 Hz),
1:30 (8 or 10 poles) (available at 2 Hz or higher when the rating is 60 Hz).
For regenerative driving:
1:12 (2 to 10 poles) (available at 5 Hz or higher when the rating is 60 Hz).
5 - 136
Parameters