11.10 n: Special Adjustment
1006 YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual
• If fast changes in the load cause hunting, increase the setting value in 0.1-unit increments. If you cannot stop
hunting, set n8-51 [Pull-in Current @ Acceleration] to 0% and set n8-54 to 0.00 s, and disable compensation
for voltage errors.
■ n8-55: Motor to Load Inertia Ratio
No.
(Hex.)
Name Description
Default
(Range)
n8-55
(056E)
Motor to Load Inertia
Ratio
Sets the ratio between motor inertia and machine inertia.
0
(0 - 3)
Adjust this parameter in the these conditions:
• If torque and speed response is unsatisfactory, gradually increase the setting.
• If motors do not start smoothly, gradually increase the setting.
• If the motor stalls during run at constant speed, gradually increase the setting.
• If there is vibration or hunting, decrease the setting.
Note:
• If the value too low, the drive will detect STPo [Motor Step-Out Detected].
• If you use one motor or more than motor at low inertia and the value is too high, there can be vibration in the motor.
0 : Below 1:10
Use this setting in these conditions:
• The ratio between the motor inertia and machine inertia is less than 1:10
• There are large current ripples
1 : Between 1:10 and 1:30
Use this setting in these conditions:
• The ratio between the motor inertia and machine inertia is approximately 1:10 to 1:30
• Parameter n8-55 = 0 and the drive detects STPo because of an impact load or sudden acceleration/deceleration.
2 : Between 1:30 and 1:50
Use this setting in these conditions:
• The ratio between the motor inertia and machine inertia is approximately 1:30 to 1:50
• Parameter n8-55 = 1 and the drive detects STPo because of an impact load or sudden acceleration/deceleration.
3 : Beyond 1:50
Use this setting in these conditions:
• The ratio between the motor inertia and machine inertia is more than 1:50
• Parameter n8-55 = 2 and the drive detects STPo because of an impact load or sudden acceleration/deceleration.
■ n8-57: HFI Overlap Selection
No.
(Hex.)
Name Description
Default
(Range)
n8-57
(0574)
HFI Overlap
Selection
Sets the function that detects motor speed with high frequency injection.
0
(0, 1)
Note:
• When there is high frequency injection, the motor will make an excitation sound.
• When you use Zero Speed Control, set E1-09 [Minimum Output Frequency] = 0.0.
0 : Disabled
Use this setting with SPM motors. The speed control range is approximately 1:20.
When n8-57 = 0, you cannot set E1-09 [Minimum Output Frequency] ≤ 1/20 of the value of E1-06 [Base
Frequency].
1 : Enabled
Use this setting with IPM motors. The speed control range changes to 1:100 for very accurate speed detection.