Mitsubishi Electric FR-A700 Series, Technical Manual

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325
PARAMETER
2
P
ARAM
ETE
R
2.12.5 Pre-excitation (zero speed control, servo lock) [Pr. 10, 11, 802, 850]
(A700)
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. 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.
(1) Control block diagram
(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.
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.
A700
[Pr. ] Name Initial Value
Setting
Range
Description
10
DC injection brake operation
frequency
3Hz
0 to 120Hz
Set the operation frequency of the DC injection brake (zero
speed control, servo lock).
9999 Operated at [ Pr. 13 ] or less.
11
DC injection brake operation
time
0.5s
0 Without DC injection brake (zero speed control, servo lock)
0.1 to 10s
Set the operation time of the DC injection brake (zero speed
control, servo lock).
8888 Operates when X13 signal is ON
802
Pre-excitation
selection
0
0 Zero speed control
1 Servo lock
850 Brake operation selection 0
0 DC injection brake operation
1 Zero speed control
Zero speed control
0r/min speed
command
Servo lock
0rad position
command
[ Pr. 850 = 1]
Real sensorless vector control
Vector control
Vector control
[ Pr. 802 = 1]
[ Pr. 802 = 0]
Position
control
Speed
control
Motor
Operation
frequency
Time
[ Pr. 10 ]
Zero speed control
Servo lock
When [ Pr. 850 = 1]
Operation time
ON
Normal operation Normal operation [
Pr. 11
]
(Hz)
Output frequency
LX signal