Mitsubishi Electric FR-A720-0.4K Instruction Manual page 133

Torque control by Real sensorless vector
control, vector control
(3) Operation example (when Pr. 804 = "0")
Torque control is enabled if the actual speed is less than the speed limit value.
When the actual speed reaches or exceeds the speed limit value, speed limit operation starts, torque control is
stopped, and speed control (proportional control) starts.
The following shows the operations in response to the analog input command from terminal 1.
Speed
Speed
STF
(Forward rotation
command)
OL
1) When STF signal is turned ON, the speed limit value is increased according to the time set in Pr. 7 .
2) Speed control operation is performed if the actual speed rises to or above the speed limit value.
3) When the STF signal is turned OFF, the speed limit value is decreased according to the time set in Pr. 8 .
4) For torque control, the actual speed becomes constant when the torque command and load torque are
balanced.
5) The motor torque developing direction is determined by the combination of the torque command input polarity
and start signal as indicated in the following table.
Torque Command
Polarity
Positive torque
command
Negative torque
command
REMARKS
⋅ When speed limit operation starts, speed control is exercised to enable internal torque limit (Pr. 22 torque limit level) (initial
value). Speed control may not be returned to torque control in this case.
Torque limit be set to external torque limit (terminal 1, 4). (Refer to page 100.)
⋅ Undervoltage avoidance function (Pr. 261 = "11, 12") of power-failure deceleration stop function is invalid under torque control.
When Pr. 261 = "11 (12)", the inverter operates in the same manner as when "1 (2)" is set in Pr. 261.
⋅ Set linear acceleration/deceleration (Pr. 29 = "0 (initial value)") when torque control is exercised. When acceleration/
deceleration patterns other than the linear acceleration/deceleration are selected, the protective function of the inverter may
function. (Refer to page 176)
CAUTION
⋅ Performing pre-excitation (LX signal and X13 signal) under torque control (Real sensorless vector control) may start the motor
running at a low speed even when the start command (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. Perform pre-excitation after making sure that there will be no problem in
safety if the motor runs.
122
Speed limit value
Pr. 7
*
Speed limit
Torque control operation
operation
(Speed control)
ON
*When the speed limit activates, torque according to the commanded is not developed.
STF signal ON
Forward rotation direction (forward rotation
driving/reverse rotation regeneration)
Reverse rotation direction (forward rotation
regeneration/reverse rotation driving)
*
Speed limit
operation
(Speed control)
ON
Torque Developing Direction
Reverse rotation direction (forward rotation
regeneration/reverse rotation driving)
Forward rotation direction (forward rotation
driving/reverse rotation regeneration)
Pr. 8
*
Time
Torque Speed limit
control operation
operation
(Speed control)
ON
STR signal ON