Chapter 5 Function parameter
73
Figure 5-12:
Schematic diagram of multi-point V/F curve setting
V/F Slip compensation coefficient
This parameter is valid only for asynchronous motors.
V/F slip compensation can compensate for the speed deviation of asynchronous motor
when the load increases, so as to keep stable speed when the load changes.
If V/F slip compensation gain is set to 100.0%, it means that the compensated deviation is
equal to the rated motor slip under the rated motor load mode, while the rated motor slip can be
calculated through b0 group of motor rated frequency and rated speed.
When adjusting V/F slip compensation gain, generally it is based on the principle that the
motor speed is same as the target speed. When the motor speed is different from target value, it
is necessary to appropriately fine-tune the gain.
In the process of the inverter's deceleration, the over-excitation control can suppress the
rise of bus voltage to avoid overvoltage fault. The greater overexcitation gain, the stronger the
inhibitory effect.
For the occasions that the inverter’s deceleration easily cause over pressure alarm, the
overexcitation gain needs to be improved. But if overexcitation gain is too large, which easily
lead to the increase of output current, you need to weigh in practical applications.
For the small inertia occasions that the inverter’s deceleration will not cause voltage rise, it
is recommended to et overexcitation gain as 0 ; the set value is also suitable for the occasions
with braking resistor.
V/F Oscillation suppression gain
The method of selecting gain is take the value as smaller as possible with the premise that
effectively suppressing oscillation, in order to avoid the adverse affect caused by V/F running.
Please select 0 as the gain when the motor has not oscillation phenomenon. Only increase gain
value when the motor has obvious oscillation , the greater gain, the more obvious the
suppression of oscillation.
When using the function of oscillation suppression, which requires that the motor’s rated
current and no-load current parameters must be accurate, otherwise V/F oscillation suppression
is ineffective.
V/F separation voltage source
High-speed pulse setting (DI5)
100.0% corresponding to the motor rated voltage (b0.02)
V/F separation voltage digital setting
0V to rated motor voltage
V/F separation voltage rise time
5-2-7.F5 group Vector control parameter
F5 function code is only valid to vector control, invalid to V/F control
Proportion of speed loop G1
Proportion of speed loop G2
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