Mitsubishi Electric MELSEC iQ-R RD78G4 - Phase Compensation Function

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4 ADVANCED SYNCHRONOUS CONTROL
4.8 Phase Compensation Function
4.8 Phase Compensation Function
In synchronous control, delays in progresses, etc. cause the phase to deviate at the output axis motor shaft end with respect
to the input axis (servo input axis or synchronous encoder axis). The phase compensation function compensates in this case
so that the phase does not deviate.
Phase compensation can be set for the input and the output axis. It is possible to compensate using the delay time inherent to
the system based on the servo input axis or the synchronous encoder axis on the input axis side. It is also possible to use a
compensation delay time equivalent to the position deviation for each servo amplifier on the output axis side.
Phase compensation of delay time of the input axis
Set delay time inherent to the system in the phase compensation advance time of the input axis ("[Pr.302] Servo input axis
phase compensation advance time", "[Pr.326] Synchronous encoder axis phase compensation advance time").
The delay time inherent to the system is shown below.
■Delay time inherent to the system for a servo input axis
■Delay time inherent to the system for a synchronous encoder axis
Phase compensation of delay time of the output axis
Set the delay time equivalent to the position deviation of the servo amplifier in "[Pr.444] Cam axis phase compensation
advance time" for the output axis. The delay time equivalent to the position deviation of the servo amplifier is calculated using
the following formula. (When using MR-J5(W)-G)
Delay time[s] = 1000000 / Servo parameter "Model loop gain (PB07)"
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.
Operation cycle[ms] [Pr.300] Servo input axis type
Command position
value
Actual position value Command to servo
amplifier
Feedback value
0.25 0[s] 2000[s] 0[s] 2000[s]
0.50 0[s] 3250[s] 0[s] 3250[s]
1.00 0[s] 5751[s] 0[s] 5751[s]
2.00 0[s] 10751[s] 0[s] 10751[s]
4.00 0[s] 20751[s] 0[s] 20751[s]
Operation cycle[ms] [Pr.320] Synchronous encoder axis type
Synchronous encoder via servo amplifier Synchronous encoder via CPU
0.25 2000[s] 2000 + Scan time[s]
0.50 3251[s] 3252 + Scan time[s]
1.00 5760[s] 5751 + Scan time[s]
2.00 10754[s] 10751 + Scan time[s]
4.00 20763[s] 20750 + Scan time[s]