Position control by vector control
(2) Control block diagram
Pr. 4 to 6
Pr. 24 to 27
Pr. 232 to 239
(Pr. 44, Pr. 110)(Pr. 45, Pr. 111)
Command pulse selection
(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.
⋅ For conditional 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.
⋅ For the servo on signal (LX), set "23" in Pr. 178 to Pr. 189 (input terminal function selection) to assign the function.
⋅ For the in-position signal (Y36), set "36" in Pr. 190 to Pr. 196 (output terminal function selection) to assign the function.
Pr. 465 to Pr. 494
Droop pulse value
Pulse train Rough
Pr. 422 +
Stop settling time