Position Control By Vector Control - Mitsubishi Electric FR-A700 Technical Manual

2.11 Position control by vector control

2.11.1 Position control
(1) Control block diagram
The following shows a basic control block diagram during position control.
RH
[Pr. 4 to 6]
[Pr. 24 to 27]
RM
[Pr. 232 to 239]
RL
REX
STF
STR
Command pulse selection
Command pulse
Command pulse
(FR-A7AL)
selection
[Pr. 428]
PGP, PP
Command pulse
(FR-A7AL)
PGN, NP
Command pulse Command pulse
selection
JOG
[Pr. 428]
Pulse train sign
NP
(2) 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 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 decreases,
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.
A700
(A700)
Position command
source selection
[Pr. 465 to 494]
travel
Multi-speed,
communication
[Pr. 8, 45, 111]
[Pr. 7, 44, 110]
[Pr. 419 = 1]
[Pr. 419 = 2]
[Pr. 419 = 0]
Position command
acceleration/deceleration
time constant
Electronic
[Pr. 424]
gear
[Pr. 420]
[Pr. 421]
Pulse train Rough
LX signal
Servo ON
STF (STR)
Forward (reverse)
Y36 signal
In-position signal
For conditional position control function by contact
input, the terminals STF and STR 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 fine
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.
308
PARAMETER
Position feed
forward
command filter
[Pr. 425]
Position feed
forward gain
[Pr. 423]
+
Position
+ +
Deviation
loop gain
- counter -
[Pr. 422]
[Pr. 429]
Differentiation
Clear signal
selection
Droop pulse value
Pulse distribution
Acceleration Deceleration
Fine
Speed control
IM
Encoder
Motor speed
Time
Stop
settling time
Rough