Mitsubishi Electric FR-A800 Series Instruction Manual page 599

3.
Pr.398 Orientation speed gain (D term) is the lag/advance compensation gain.
The limit cycle
torque decreases in relation to the position deviation, and the motor stops with deviation.
*1 Servo rigidity: The response when a position control loop is configured.
When the servo rigidity is raised, the holding force increases and operation becomes stabilized, but vibration occurs more easily.
When the servo rigidity is lowered, the holding force decreases, and the settling time increases.
*2 Rocking: Movement in which return occurs when the stopping position is exceeded.
*3 Limit cycle: This is a phenomenon that generates ± continuous vibration centering on the target position.
• Application of lag/advance control and PI control
PI control can be applied by setting Pr.398 to 0. Normally, use the lag/advance control. PI control should be used when using
a machine with a high spindle static friction torque and requires a stop position accuracy.
 Pr.399 Orientation deceleration ratio (initial value: 20) (Vector control)
• Make adjustments, as shown below, according to the orientation status. (Make adjustments in the order of a, b, and c.)
Normally, adjust Pr.362 Orientation position loop gain in the range from 5 to 20, and Pr.399 Orientation deceleration
ratio from 5 to 50.
Rocking occurs during stopping
The orientation time is long.
Hunting occurs during stopping
Low servo rigidity during stopping
NOTE
• Orientation stop operation fails, causing an excessive position error, or if the motor performs forward/reverse reciprocation
operation, review the settings of Pr.393 Orientation selection (on
page
 Pr.351 Orientation speed (initial value: 2 Hz) (Vector control)
• Set the speed when switching between the speed control mode and the position control mode is performed under
orientation operation.
Decreasing the set speed enables stable orientation stop. Note that the orientation time increases.
Pr.351 Orientation speed
Orientation start
Orientation complete
Encoder Z phase pulse
NOTE
• When "19" is set in Pr.52 Operation panel main monitor selection, the position pulse monitor is displayed instead of the
output voltage monitor on the PU.
598
5. PARAMETERS
5.14 (A) Application parameters
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*3
can be prevented by increasing the value, and operation can be stopped stably. However, the
Condition
586).
[Hz]
Frequency
ON
OFF
(X22)
(ORA)
search engine
Adjustment procedure
a. Decrease the Pr.399 setting.
b. Decrease the Pr.362 setting.
c. Increase the Pr.396 and Pr.397 settings.
a. Increase the Pr.399 setting.
b. Increase the Pr.362 setting.
a. Decrease the Pr.362 setting.
b. Decrease the Pr.396 setting and increase the Pr.397 setting.
a. Increase the Pr.396 setting and decrease the Pr.397 setting.
b. Increase the Pr.362 setting.
page 587) and Pr.359 Encoder rotation direction (on
Decelerate according to the deceleration ratio of Pr.399
Orientation command completion
Time[t]
ON