FR-A701 INSTRUCTION MANUAL (Applied) - Automation Systems ...

Speed control by real sensorless vectorcontrol, vector control4 Motor speed is unstable.5678Phenomenon Cause CountermeasuresMotor or machine hunts(vibration/noise isproduced).Acceleration/decelerationtime does not match thesetting.Machine operation isunstableSpeed fluctuates at lowspeed.(1) The speed command varies. (1) -1 Check that a correct speed command comes fromthe command device. (Take measures againstnoises.)(1) -2 Decrease Pr. 72 PWM frequency selection.(1) -3 Increase Pr. 822 Speed setting filter 1. (Refer to page 265 )(2) Insufficient torque. (2) Increase the torque limit value.(Refer to torque limit of speed control on page 83 )(3) The speed control gains do notmatch the machine. (mechanicalresonance)(3) -1 Perform easy gain tuning. (Refer to page 89 )(3) -2 Adjust Pr. 820, Pr. 821. (Refer to page 91)(3) -3 Perform speed feed forward/model adaptive speedcontrol.(1) The speed control gain is high. (1) -1 Perform easy gain tuning. (Refer to page 89)(1) -2 Decrease Pr. 820 and increase Pr. 821.(1) -3 Perform speed feed foward control and modeladaptive speed control.(2) The torque control gain is high. (2) Decrease the Pr. 824 value.(3) The motor wiring is wrong. (3) Check the wiring(1) Insufficient torque. (1) -1 Increase the torque limit value.(Refer to torque limit of speed control on page 83 )(1) -2 Perform speed feed foward control.(2) Large load inertia. (2) Set the acceleration/deceleration time that meets theload.(1) The speed control gains do notmatch the machine.(2) Slow response because ofimproper acceleration/deceleration time of the inverter.(1) -1 Perform easy gain tuning. (Refer to page 89)(1) -2 Adjust Pr. 820, Pr. 821. (Refer to page 91)(1) -3 Perform speed feed foward control and modeladaptive speed control.(2) Change the acceleration/deceleration time to anoptimum value.(1) Adverse effect of high carrier (1) Decrease Pr. 72 PWM frequency selection.frequency.(2) Low speed control gain. (2) Increase Pr. 820 Speed control P gain 1.94