Mitsubishi Electric FR-F720P-0.75K to 110K Instruction Manual page 97

IPM motor control <IPM>
Condition
Acceleration/deceleration
5 time is different from the
setting.
Machine movement is
6
unstable.
Rotation ripple occurs
7 during the low-speed
operation.
86
Possible cause
(1) Torque shortage
(2) Load inertia is too high.
(1) Speed control gain is not
suitable for the machine.
(2) Response is slow because of
the inverter's acceleration/
deceleration time setting.
(1) High carrier frequency is
affecting the motor rotation.
(2) Speed control gain is too low.
Countermeasure
(1) Raise the stall prevention operation level. (Refer to
page 91.)
(2) Set acceleration/deceleration time suitable for the
load.
(1) Adjust Pr.820 and Pr.821 (Refer to page 84.)
(2) Set the optimum acceleration/deceleration time.
(1) Lower Pr.72 PWM frequency selection.
(2) Raise Pr.820 Speed control P gain 1.