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Position control by vector control
(2) Control block diagram
RH
Pr. 4 to 6
Pr. 24 to 27
RM
Pr. 232 to 239
RL
REX
STF
STR
(Pr. 44, Pr. 110)(Pr. 45, Pr. 111)
Command pulse
Command pulse selection
(FR-A7AL)
Pr. 428
PGP, PP
Command pulse
(FR-A7AL)
PGN, NP
Command pulse selection
Command pulse
Pr. 428
JOG
Pulse train
sign
NP
(3) Example of operation
The speed command given to rotate the motor is calculated to zero the difference between the number of internal
command pulse train pulses (when Pr. 419 = 0, the number of pulses set by parameter (Pr. 465 to Pr. 494) is changed to
the command pulses in the inverter) and the number of pulses fed back from the motor end encoder.
1) When a pulse train is input, pulses are accumulated in the deviation counter and these droop pulses act as position
control pulses to give the speed command.
2) As soon as the motor starts running under the speed command of the inverter, the encoder generates feed back
pulses and the droop of the deviation counter is counted down. The deviation counter maintains a given droop pulse
value to keep the motor running.
3) When the command pulse input stops, the droop pulses of the deviation counter decrease, reducing the speed. The
motor stops when there are no droop pulses.
4) When the number of droop pulses has fallen below the value set in Pr. 426 In-position width , it is regarded as
completion of positioning and the in-position signal (Y36) turns ON.
LX signal
Servo on
STF (STR)
Forward (reverse)
Y36 signal
In-position signal
For simple position control function by contact input, the STF and STR terminals provide the forward (reverse)
command signal. The motor can run only in the direction where the forward (reverse) signal is ON. Turning the STF
signal OFF does not run the motor forward and turning the STR signal OFF does not run the motor reverse.
The pulse train is rough during acceleration and coarse at the maximum speed. During deceleration the pulse train is
rough and at last there are no pulses. The motor stops shortly after the command pulses stop.
This time lag is necessary for maintaining the stop accuracy and called stop settling time.
132
Position command
source selection
Pr. 465 to Pr. 494
travel
Multi-speed,
communication
Pr.7
Pr.8
Droop pulse value
Acceleration
Pulse train Rough
Pr. 419
0
Position command
acceleration/deceleration
time constant
Electronic
Pr. 424
gear
1
Pr. 420
Pr. 421
2
Pulse distribution
Deceleration
Fine
Position feed
forward
Position feed
command filter
forward gain
Pr. 425
Pr. 423
Position
loop gain
Pr. 422 +
+
Deviation
+
counter
-
-
Pr. 429
Differentiation
Clear signal
selection
Motor speed
Time
Stop settling time
Rough
Speed control
IM
Encoder
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