Mitsubishi Electric LD77MH, User Manual

Page: 165 / 238

4 - 61
Chapter 4 Synchronous Control
Phase compensation of delay time of the output axis
Set delay time equivalent to the position deviation on the servo amplifier in "[Pr.444] Cam
axis phase compensation advance time" for the output axis. The delay time equivalent to
position deviation of the servo amplifier is calculated using the following formula. (MR-
J3(W)-B, MR-J4(W)-B, MR-J4-GF, and MR-JE-B use)
Delay time [ μ s] =
1000000
Servo parameter "Model loop gain"(PB07)
(Note): When the feed forward gain is set, the delay time is set to a smaller value than
the value listed above.
The model loop gain will change when the gain adjustment method is auto tuning mode 1
or 2. The model loop gain must not be changed on the axis executing phase compensation
through preventing change with the manual mode or interpolation mode setting.
Setting example
When axis 1 is synchronized with an incremental synchronous encoder axis, the phase
compensation advance time is set as follows.
(If the operation cycle is as 1.77 [ms] and model loop gain of axis 1 is as 80.)
Setting item Setting value
[Pr.326] Synchronous encoder axis
phase compensation
advance time
QD77MS : 3953 [ μ s]
QD77GF : 4968 [ μ s]
LD77MS : 4045 [ μ s]
LD77MH : 4036 [ μ s]
(Reference: Delay time peculiar to system for a
synchronous encoder axis)
[Pr.444] Cam axis phase
compensation advance time
1000000
80
= 12500 [ μ s]
When overshoot or undershoot occurs during acceleration/deceleration, set a longer time
for the phase compensation time constant.