Mitsubishi Electric FR-A700 Technical Manual page 291

2.12.5 Pre-excitation (zero speed control, servo lock) [Pr. 10, 11, 802, 850]
When the start signal (STF, STR) is not input to the inverter
(during a stop), turning ON the pre-excitation signal LX
enables 0 speed control or servo lock.
At deceleration to stop, either zero speed control or stop
with servo lock is selectable even if pre-excitation signal LX
is not input.
Zero speed control can be selected during Real sensorless
vector control and either zero speed control or servo lock
can be selected under vector control.
[Pr. ] Name
DC injection brake operation
10
frequency
DC injection brake operation
11
time
Pre-excitation
802
selection
850 Brake operation selection
(1) Control block diagram
Zero speed control
0r/min speed
command
Servo lock
0rad position
command
(2) Operation
When the LX signal is turned ON under Real sensorless
vector control or vector control, pre-excitation (zero speed
control, servo lock) is performed during a stop.
For the terminal used for LX signal input, set 23 in any of
[Pr. 178 to 189] to assign the function.
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.
Although FWD/REV of the operation panel is not lit during
pre-excitation, note that voltage is applied to the motor.
Setting
Initial Value
Range
0 to 120Hz
3Hz
9999
0
0.5s 0.1 to 10s
8888
0
0
1
0
0
1
[Pr. 850 = 1]
[Pr. 802 = 0]
[Pr. 802 = 1]
Position
control
325
In DC injection brake operation, DC voltage is directly
applied to the motor to prevent the motor shaft from
rotating. In zero speed control, vector control is performed
to maintain 0r/min. In either control, the motor will not
return to the original position if the motor shaft rotates due
to external force.
The motor shaft position is maintained with servo rock. The
motor will return to the original position if the motor shaft
rotates due to external force.
Description
Set the operation frequency of the DC injection brake (zero
speed control, servo lock).
Operated at [Pr. 13] or less.
Without DC injection brake (zero speed control, servo lock)
Set the operation time of the DC injection brake (zero speed
control, servo lock).
Operates when X13 signal is ON
Zero speed control
Servo lock
DC injection brake operation
Zero speed control
Real sensorless vector control
Vector control
Vector control
Speed
control
When offline auto tuning [Pr. 96 Auto tuning setting/status = 1
or 101] is performed during pre-excitation, offline auto
tuning is not executed. However, take note that the motor
starts rotation.
When [Pr. 850 = 1]
(Hz)
Zero speed control
Servo lock
Normal operation [Pr. 11]
Operation time
LX signal
PARAMETER
A700
(A700)
Motor
[Pr. 10]
Operation
frequency
Time
Normal operation
ON
2