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Special operation and frequency control
4.25.4 Droop control (Pr. 286 to Pr. 288)
CAUTION
When the load is light, the motor may suddenly accelerate to 120Hz maximum, causing hazard.
Securely provide mechanical interlock on the machine side to perform.
♦ Parameters referred to ♦
Pr. 4 to Pr. 6, Pr. 24 to Pr. 27 (multi-speed setting) Refer to page 165
Pr. 59 Remote function selection Refer to page 169
Pr. 79 Operation mode selection Refer to page 313
Pr. 128 PID action selection Refer to page 361
Pr. 178 to Pr. 189 (input terminal function selection) Refer to page 231
This function is designed to balance the load in proportion to the load torque to provide the speed drooping
characteristic under Advanced magnetic flux vector control, Real sensorless vector control and vector control.
This function is effective for balancing the load when using multiple inverters
Parameter
Number
Name
Initial
Value
Setting
Range
Description
286 Droop gain 0%
0 Normal operation
0.1% to
100%
Droop control is valid
Set the drooping amount at the rated torque as a
percentage with respect to the rated motor frequency.
287 Droop filter time constant 0.3s 0 to 1s
Set the time constant of the filter applied on the torque
amount current.
288
Droop function activation
selection
0
0
Droop control is not exercised during acceleration/
deceleration.
1
Droop control is always exercised during operation. (with
0 limit)
2
Droop control is always exercised during operation.
(without 0 limit)
10
Droop control is not exercised during acceleration/
deceleration. (Motor speed is referenced)
11
Droop control is always exercised during operation.
(Motor speed is referenced)
(1) Droop control
· The output frequency is changed according to
the magnitude of torque amount current under
Advanced magnetic flux vector control, Real
sensorless vector control and vector control.
The drooping amount at the rated torque is set
by the droop gain as a percentage using the
rated frequency (Motor speed when Pr. 288 =
"10, 11") as a reference.
· The maximum droop compensation frequency
is 120Hz.
When Pr. 288 = "0 to 2", or under Advanced magnetic flux vector control
Droop compensation frequency =
Amount of torque current after filtering
×
Rated motor frequency × Droop gain
Rated value of torque current 100
When Pr. 288 = "10, 11"
Droop compensation frequency =
Amount of torque current after filtering
×
Motor speed × Droop gain
Rated value of torque current 100
REMARKS
Set the droop gain to about the rated slip of the motor.
Magnetic flux
Magnetic flux
Magnetic flux
Sensorless
Sensorless
Sensorless
Vector
Vector
Vector
Droop compensation
frequency
Rated frequency
Torque
100%
Droop
gain
-100%
Frequency
0
Rated slip
=
Synchronous speed at base frequency - Rated speed
×
100[%]
Synchronous speed at base frequency