Chapter 5 Function parameter
72
Torque boost is mainly used to improve the characteristics of the torque low-frequency
under V/F control mode. If the torque boost is too low, the motor will work at the lower speed
and power. If the torque boost is too high, the motor will run with overexcitation, the inverter's
output current increases and the efficiency is reduced.
It is recommended to increase this parameter when the motor works with heavy load but
without enough torque. The torque boost can be reduced when the load is lighter. When the
torque boost is set to 0.0, the inverter will automatically perform torque boost, the inverter can
automatically calculates the required torque boost value according to the motor stator resistance
parameters.
Torque boost cutoff frequency: Torque boost is valid below this frequency, invalid above
the set frequency.
V1
Output frequency
f1
Vb
Output Voltage
fb
V1: Manual torque boost voltage Vb: Maximum output voltage
f1: Manual torque boost cut-off frequency fb: Rated operating frequency
Figure 5-11:
Schematic diagram of manual torque boost voltage
Multipoint V/F frequency point 1
Multipoint V/F voltage point 1
Multipoint V/F frequency point 2
Multipoint V/F voltage point 2
Multipoint V/F frequency point 3
F4.05～b0.04(rated motor
frequency)
Multipoint V/F voltage point 3
F4.03 to F4.08 six parameters are used to define multi-point V/F curve.
The multi-point V/F curve is set according to the load characteristics of motor, please be
noted that the relationship between three voltage points and three frequency points must be
meet: V1 <V2 <V3, F1 <F2 <F3. The setting of multi-point V/F curve is as shown in below
figure.
In the sate of low frequency, if the voltage is set to a higher value, which may cause motor
overheating even burned, the inverter may appear overcurrent stall or overcurrent protection.
V1
Frequency
F1
Vb
Voltage%
Fb
V1-V3: Voltage percentage of stage 1-3 to multi-speed V/F
F1-F3: Frequency percentage of stage 1-3 to multi-speed V/F
Vb: Rated motor voltage
Fb: Rated motor operating frequency
V3
V2
F2 F3
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