Mitsubishi Electric FR-A820-00046 Instruction Manual page 290

Speed control under Real sensorless vector control, vector control, PM sensorless vector control
Speed feed forward control (Pr. 877 = "1")
● When the load inertia ratio is set in Pr. 880, the required torque for the set inertia is calculated
according to the acceleration and deceleration commands, and the torque is generated quickly.
● When the speed feed forward gain is 100%, the calculation result for speed feed forward is applied
as is.
● If the speed command changes suddenly, the torque is increased by the speed feed forward
calculation. The maximum limit for the speed feed forward torque is set in Pr. 879.
● The speed feed forward result can also be lessened with a primary delay filter in Pr. 878.
Speed
command
Fig. 5-29:
NOTES The speed feed forward control is enabled for the first motor.
Even if the driven motor is switched to the second motor while Pr. 877 = "1", the second motor is
operated as Pr. 877 = "0".
Under PM sensorless vector control, this function is available when low-speed range high-torque
characteristic is enabled by Pr. 788 "Low speed range torque characteristic selection" = "9999 (ini-
tial value)". (Refer to page 5-75.)
5 - 110
Speed feed forward control
Load inertia ratio
Speed feed
forward
J•s
gain
[Pr. 880]
[Pr. 881]
Speed
+
control P
gain 1
[Pr. 820]
-
Actual speed controller
Block diagram of speed feed forward control
[Pr. 879] [Pr. 878]
Speed feed Speed feed
forward
forward torque
limit limit
+
+
+
Speed control
integral time 1
[Pr. 821]
Parameters
Torque
M
control
Speed
estimator
I002520E