Description of Function Codes
MD380 User Manual
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These six parameters are used to dene the multi-point V/F curve.
The multi-point V/F curve is set based on the motor's load characteristic. The relationship
between voltages and frequencies is:
V1 < V2 < V3, F1 < F2 < F3
At low frequency, higher voltage may cause overheat or even burnt out of the motor and
overcurrent stall or overcurrent protection of the AC drive.
Figure 6-5 Setting of multi-point V/F curve
Frequency %
Voltage
%
V3
FbF1
V1
Vb: Rated motor voltage
V1-V3: 1st, 2nd and 3rd voltage
percentages of multi-point V/F
Fb: Rated motor running frequency
F2 F3
V2
Vb
F1-F3: 1st, 2nd and 3rd frequency
percentages of multi-point V/F
Function Code Parameter Name Setting Range Default
F3-09 V/F slip compensation gain 0%–200.0% 0.0%
This parameter is valid only for the asynchronous motor.
It can compensate the rotational speed slip of the asynchronous motor when the load of the
motor increases, stabilizing the motor speed in case of load change. If this parameter is set
to 100%, it indicates that the compensation when the motor bears rated load is the rated
motor slip. The rated motor slip is automatically obtained by the AC drive through calculation
based on the rated motor frequency and rated motor rotational speed in group F1.
Generally, if the motor rotational speed is different from the target speed, slightly adjust this
parameter.
Function Code Parameter Name Setting Range Default
F3-10 V/F over-excitation gain 0–200 64
During deceleration of the AC drive, over-excitation can restrain rise of the bus voltage,
preventing the overvoltage fault. The larger the over-excitation is, the better the restraining
result is.
Increase the over-excitation gain if the AC drive is liable to overvoltage error during
deceleration. However, too large over-excitation gain may lead to an increase in the output
current. Set F3-09 to a proper value in actual applications.
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