Mitsubishi Electric FR-A800, Instruction Manual

Page: 310 / 1042

Torque control under Real sensorless vector control and vector control Parameters
5 - 130
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 5-219.)
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).